A gable roof is used for various wooden houses. You can even assemble the structure with your own hands, since it is simple, unlike a hipped or attic one. The main building materials for installation are boards and beams made of timber or logs. After reading the article to the end, readers will learn what the main elements of a gable roof frame are, and how to assemble it with your own hands and calculate the cross-section and length of the beams. About.
The rafter system of a gable roof for the construction of a house made of timber consists of: a rafter leg, a mauerlat, a filly, a ridge, struts, racks and sheathing. In order to assemble it with your own hands, you need to imagine the entire structure. We'll talk more about each element below.
Mauerlat
Mauerlat is the main load-bearing part of the gable roof frame structure. It consists of timber located around the entire perimeter of the house, on load-bearing walls. For the construction of a house from laminated veneer lumber or other type of lumber, it is secured using ties and metal brackets.
Through the Mauerlat, the load from the entire rafter system is transferred to the load-bearing walls of the house. The size of the Mauerlat for a wooden house is suitable 100x100 mm or 150x150 mm. Coniferous wood is used for this unit. Before laying, the timber is treated with an antiseptic and waterproofed using bitumen tape.
Rafter leg
The main contour of the future roof is assembled from the rafter legs. For the roof frame of a wooden house, material with a cross section of 50x150 or 100x150 mm is used. Stacked rafter legs in the shape of a triangle. The entire system rests on the rafter legs, and whether the roof can withstand wind and snow loads depends on the quality of the material.
The weight of the entire roof structure is transferred through the legs to the Mauerlat. The rafter legs are mounted in increments of 60-120 cm, depending on the weight and fastening of the future roof. The heavier it is, the more frequent the installation step of the legs of the rafter system.
Horse
The ridge is the connecting beam of the two rafter parts of the slope at the top. It is mounted strictly horizontally at the joint of the legs.
For a wooden gable roof, a beam with a section of 100x100 mm is used as a ridge. It is pre-treated with an antiseptic.
filly
The filly is an element that plays the role of a roof overhang. This part is attached to the rafter leg if its length is not enough to form an overhang of at least 200 mm. If the rafter leg is enough, then you don’t have to mount the filly.
For installation, boards of a smaller size and cross-section than the legs are used. The filly makes installation of the frame easier, since the beams for the legs no longer need a long length. If you assemble the roof yourself, then experts recommend choosing this option.
Sill
This is a beam that is placed horizontally on the internal load-bearing walls of the log house. The beam bears the main load from the racks of the rafter system, and it transfers it load-bearing wall.
The installation uses material with a cross-section of 100x100-150x150 mm.
Racks
The drains are attached vertically from the ridge to the internal load-bearing wall. For their manufacture, material with a cross section of 100x100-150x150 mm is used after calculations. In the rafter system, they play the role of redistributing the load from the ridge to the load-bearing wall. 
Puffs
The ties connected to the legs of the frame have the shape of a triangle. This fastener in system. It is thanks to the tightening that the legs do not run away in different directions under the pressure of the structure and roof.
Struts
The struts consist of pieces of boards mounted at an angle. With the help of struts, the load from the rafter legs is redistributed to the load-bearing walls. In connection with the tie rods, the struts form trusses. The truss consists of several struts and one tie. Trusses are used to transfer the load if the spans are too large.
Lathing
Roof sheathing device
They make the sheathing from boards or thin bars. In the rafter system, the sheathing is attached perpendicular to the legs. With the help of lathing, the load from roofing structure(roofing, insulation, vapor barrier -), evenly distributed over all rafter legs. Another function of the lathing is to connect the rafter legs together into a single system. Even a non-edged board is suitable as a sheathing. But first you need to peel off the bark from it.
If the roof is rolled, for example bitumen, then instead of boards, plywood sheets are used as sheathing. This way the roofing substrate acquires a hard and even surface, on which it is easy to roll out the same roofing material.
All of the listed parts of the gable structure frame are dried and treated with antiseptic impregnations before installation; you can do this yourself. Otherwise, the rafter system will quickly rot.
What kind of rafter system is there for a gable roof?
The rafter contraction for a gable roof for the construction of a house made of profiled timber can be used suspended or suspended.
Hanging structure
This system has a structure based on the side load-bearing walls of the log house. But at the same time, the rafters negatively interact with the walls, pushing them apart. To avoid this, in the frame of a gable roof the legs are tightened with special ties. The ties and legs form a triangular mount, which has rigid ribs, and the structure does not deform over time.
In a rafter structure, the role of tie bars can be played by floor beams. This way the structure can be used as an attic. For greater strength, a tightening is also installed on top of the rafter part at least 50 cm from the roof ridge.
It is necessary to make such a design if the span between the load-bearing walls of the log house is no more than 10 cm. If this span is larger and there is a load-bearing wall between it that divides it in half, then a hanging system can be installed
Layered structures
The layered rafter system is installed on a log house with any span. Its peculiarity is the support beam, which is located in the middle of the wall span. It is advisable to use such a design when the distance between load-bearing walls is more than 10 m.
If there is a load-bearing column between the main load-bearing walls, then you can use the attic version of layered rafters. In this case, the rafters will be attached to the column, and additional rafters will be made between the columns. But doing it without certain skills is difficult.
How to calculate roof rafters
Before you start making a roof frame with your own hands, you need to calculate the length and thickness of the beams.
Calculation of beam sections
The cross-section of rafter beams is directly related to their length and fastening pitch. To determine the ratio of these indicators, there are special calculators with which it is not difficult to make calculations and GOST standards.
Calculation of the ratio of the length and cross-section of beams in the form of a table:
| Rafter beam length, m | Section of the material used, mm | Rafter pitch, m | |
|---|---|---|---|
| Beam or board | Log | ||
| From 1-3 | 80x100, 90x100, 90x160 | 100, 150, 160 | 1 – 1,35 |
| From 3-4 | 80x160, 80x180, 90x180 | 160, 180 | 1,40 – 1,70 |
| From 4-5 | 80x200, 100x200 | 200 | 1,40 – 1,75 |
| From 5-5.8 | 100x200 | 200 | 1,10 – 1,40 |
| From 5.9-6.5 | 120x220 | 240 | 1,10 – 1,40 |
Judging by the numbers, if the length of the rafters is large, then the distance between them decreases and the cross-section increases. If you take rafters of a smaller cross-section and do not make the necessary calculations, then over the years the roof will sag.
After the calculation has been made, you need to saw off the leg beams to the same length and mount each pair on that straight line.
Subtleties of installing a gable roof
The main stages of building a roof frame with your own hands consist of:
- Mounting the Mauerlat
- Installation of rafter legs
- Ridge installation
- Bunch of legs
- Lathing
How professionals install a roof can be seen in the video provided:
In the video you can see the finished frame made of timber and its description, each node clearly. Readers will find in the video the mauerlat, rafter legs, their fastening, etc.
Mauerlat fastening
IN wooden houses There is no need to mount an additional Mauerlat. Its role will be played by the top log or timber. But if the roof structure should be higher, then the timber must be tied.
The laying of the timber begins with its insulation; for this, the walls are covered with a double layer of roofing material on top. The timber is processed and laid. In the corners it is connected with your own hands using metal staples and half-section cuts.
The Mauerlat is placed strictly parallel to the opposite wall so that the rafter legs are subsequently identical.
More details on how to attach the rafters to the Mauerlat can be seen in the video below:
The video clearly shows how the fastening of legs - beams to beams should look like from professionals.
Installation of rafter legs
For the exact location of the rafter legs, pencil and meter marks are made on the mauerlat. But before this, it is necessary to draw up a diagram or calculation of their location.
The preparation of the rafter legs begins with a cut from the bottom side, 1/3 of the width is made. Their leg will rest on the mauerlat. The option of their fastening depends on what material the rafters will be made of.
The slope of the future roof will depend on the angle at which the leg beams are secured. It should not be made very flat and steep. It is better to first make a calculation according to the regional indicators. If wind loads are high in the area where you live, then the angle cannot be more than 20°C. At high precipitation rates, the slope is made at 35-40°C. This way, snow and precipitation will not accumulate, and the roof will begin to clean itself.
In the upper part, the rafter legs are connected to the ridge using iron brackets into a single structure.
Bundle of rafter legs in a hanging structure
Beams - legs are assembled together before their installation. The connecting elements can be bolts or nuts with iron plates. After completing the collection of triangular fasteners with rafter legs, they begin to install from the two outer ones. Then the next two are installed. The frame needs to be fixed with temporary jibs. At the end of installation they are removed.
After complete installation legs are attached to them by fillies. The size of the overhang of the future roof will depend on their length. For a wooden house, this distance is taken as maximum to prevent water from getting on the walls.
Installation of rafters in a layered structure
With this installation, the rafters begin to be mounted from a laying on which two supports are installed. Mounted on top of supports ridge beam. The jibs provide additional rigidity to the structure.
The rafter legs are attached to the ridge beam. If you take the length of the rafter legs a little longer and file them with a circular saw after twisting, then the work will be more productive.
Installation of sheathing
After the installation of the rafter legs is completed, they begin to attach the sheathing. In this case, marking begins from the ridge, where two massive wide boards are first mounted.
The sheathing must be installed along the entire length of the gable roof in increments of a certain roof.
When the rafter system is completely assembled, the overhang and gables of the roof are sewn up. After this, the roofing material is laid and the structure is insulated. We talked about how to properly insulate a roof HERE.
As you can see from the article, it’s not difficult to do the work yourself, and by imagining what the structure of a gable roof looks like, you can easily make a plan and calculation for your log house. It is advisable to choose the best and highest quality material that will be used during installation.
Construction of a reliable rafter system is one of the most difficult tasks when constructing the roof of a country house, cottage or garage. And yet, do not rush to give up - today we will refute the popular belief that such work is beyond the capabilities of a beginner. Knowing the rules for calculating, sawing and installing a roofing frame, you can build a roof no worse than specialists. In turn, we will try not only to talk about the structure, design and construction features of various types of rafter systems, but also share the secrets of experienced craftsmen.
What is called a rafter system and how is it structured?
Any, even the most shabby roof is based on a strong power frame called a rafter system. The rigidity of the roof, and therefore its ability to withstand even the strongest wind and snow loads, depends on how correctly this structure is installed.
The rafter system is the roof’s power frame, which absorbs all wind and snow loads
The best material for making rafters (trusses) is considered to be timber or a thick board made of wood. coniferous species. And there is an explanation for this - pine or spruce lumber is relatively light in weight, and the presence of natural resins makes it quite durable. Even if the timber has a slight residual moisture, it will not move when dried, which is no less important a factor than ease of use and long service life.
Depending on the size of the roof, the supporting elements of the structure can have a cross-section from 50x100 mm to 200x200 mm or more. In addition, the length of the roof directly affects the number of rafters, because they are installed in small increments - from 60 cm to 1.2 m.
Structural elements of the rafter system
The main requirement for a wooden frame is the ability to withstand bending and torsion. For this reason, a triangle shape is best for timber frame trusses. Moreover, they can consist of several parts:
- rafter legs - the base of the roof frame, which has the greatest influence on the size and geometry of the slopes;
- crossbars (bolts) - boards that tie together a pair of rafter legs;
- purlins are transversely installed beams, due to which the rafters are connected into a single structure;
- racks - vertical supports that serve to support rafter legs or prevent purlins from deflecting;
- struts - the same racks, only placed at an angle to the vertical;
- beds - boards attached to the attic floor on which supports are installed;
- Mauerlat - a support beam installed on load-bearing walls, to which the lower parts of the rafter legs are attached;
- fillies - pieces of timber or boards that are nailed to the lower ends of the trusses and are used to arrange roof overhangs.
Additional elements of the rafter system make the roof frame more durable, rigid and stable
When choosing a roof frame design, it is important to find that golden mean that will allow you to get a durable and reliable design at minimal cost. For this reason, you can deviate a little from the established canons, if the matter does not concern the rigidity of the entire structure. For example, it is quite possible to do without fillies, and form the eaves overhang using longer rafter legs. Or use not a solid Mauerlat, but pieces of timber laid only in the places where the rafter legs are attached - it all depends on the engineering ingenuity and experience of the roofer.
Rafter classification
Depending on the roof structure and the purpose of the attic space wooden frame may consist of several types of rafters:
Features and types of rafter systems
To make an informed choice, you need to understand the features of various types of rafter systems and know the strengths and weak sides each design.
Roof frame with hanging rafters
Since the principle of fastening hanging rafters does not require additional support points; this design is used for buildings no more than 6 m wide. Installation of unsupported trusses involves fastening each pair of legs to opposite main walls, while their upper parts are fixed directly to the ridge girder.
A roof frame with hanging rafters transfers only vertical forces to the walls, therefore it has simpler attachment points to load-bearing walls
During operation, a force acts on the hanging rafters, tending to push the structure apart. To compensate for the bursting force, a crossbar made of wooden beam or metal profile pipe. If the attic space will be used for household purposes, then the upper lintel is secured as close to the ridge as possible, and the lower edges of the pairs of rafter legs are connected with ties. This scheme allows you to increase the useful height of the attic without at all reducing the strength of the frame. By the way, if the lower lintels are made of timber with a cross-section of more than 100x100 mm, then they can also be used as load-bearing beams. It is necessary to ensure a reliable connection between the tie rods and the rafter legs, since significant pushing forces are also applied to the place where they are attached.
Roof with layered rafters
Layered rafters require the installation of at least one support, so they are used for buildings with internal load-bearing walls. Maximum length a single span should not exceed 6.5 m, otherwise the strength and rigidity of the roof frame will suffer. To increase the width of the roof, the rafter system is reinforced with intermediate supports. Even one additional post allows you to increase the width of the roof up to 12 m, and two - by more than 15 m.
The system with layered rafters is ideal option when it is necessary to build a roof of large width
The stability of layered trusses can be increased by using a sub-rafter frame with purlins, racks and struts. In addition, this rafter system requires much lower lumber costs. Versatility, durability and cost-effectiveness have long been appreciated as construction companies, and individual developers, most often using roofing structures with layered beams in their projects.
Combined options
Roofs today country houses surprise with the elegance of design, whimsicality of shapes and variety of configurations. Such complex structures can be built in only one way - by combining both types of rafter systems in one frame.
The combination of layered and hanging trusses allows you to obtain a rafter system of any configuration
Even for the construction of not the most complex sloping roofs, both rafter systems are used at once. Right-angled triangles located on the sides are layered rafter structures. And they are connected due to the upper tie, which at the same time plays the role of a tightening for the upper hanging rafters.
Procedure and rules for installing roof frames
Since two types of roof frames are used in the construction of roofs, we will consider the installation technology of each structure separately. However, before starting construction work, it is necessary to study methods of fastening structural elements to each other.
Construction of a roof with hanging rafters
It was already mentioned above that hanging rafters are most often used in the construction of small or undemanding buildings. Log house in this case, it is an almost ideal option, since you can do without a Mauerlat. The lower part of the rafter legs is attached to the upper crown or the edges of the ceiling beams (matits) protruding beyond the perimeter of the walls. In the latter case, the tie must be moved upward - this will allow the timber to be placed over the finishing log and make the attic more comfortable.
To increase the height of the attic space, the tie should be installed as close to the top of the roof as possible
Preparatory work
The geometry of the slopes depends on how well the beams for the rafters are prepared. A cord stretched between nails driven into the outer beams will help to level the supporting surfaces.
- It is necessary to cut down the slab, obtaining flat areas for installing trusses. After this, you should definitely check how accurately they lie in the same plane. This can be done with the help of a long, even rod and a level.
Before installing the trusses, the supporting surfaces are aligned with the cord
- After removing excess wood, you need to make a recess in each beam for the rafter tenon. You can draw the locations of future nests using the same nails and cord as in the previous case. Although recesses for the rafters can be made both before and after the manufacture of the trusses, experts advise making them first - this will allow fitting with more high accuracy and convenience.
The method of fastening the rafters depends on many factors - the type of support beams, their cross-section, features of the roof overhang, etc.
- Professional roofers recommend installing an additional guide - a vertical strip - in the center of the span of each gable. One of its sides is used as an axis of symmetry, which will make it possible to ensure strict adherence to the geometry of the structure.
In order to simplify the process of marking and installing the roof frame, use vertical slats installed along the center line of the roof
Making rafters
In order for the rafters to have the same dimensions and configuration, they are made according to a pre-made template. To make it, we suggest using the following instructions:
- Take two shawl boards and bolt them together to create a structure similar to a drop-down compass. The threaded connection should not be overtightened - the structure should rotate around the top. Be sure to check that the slats are 10–15 cm longer than the rafters - this will be needed to take into account the height of the abutment tooth.
The simplest template allows you to get roof trusses of the same size and configuration
- Make two marks on the staff installed as a guide. The lower one should correspond to the height of the rafter system, and the upper one should be spaced from it to the height of the mounting protrusion.
- Place the template on the matrix so that the corners of the boards rest against the recesses for the rafter teeth.
In order for the structure to successfully cope with thrust loads, the thrust tooth at the end of the rafter leg is inserted into a recess on the floor beam
- Align the axis of rotation of the “compass” with the top mark on the rail and set the height of the tenon from the lower corners of the jig.
- Lower the template down and cut the teeth along the drawn line. After this, lift the device onto the roof and insert the spikes into the sockets on the motherboard. Check that the sample axis coincides with the bottom mark on the vertical staff. If necessary, move the bolt in the desired direction and fix the angle between the boards with a cross member.
Several methods are used to fasten trusses - it all depends on the type of support beams, the design of the roof frame and the cross-section of its elements
- Having adjusted the template to the height, apply vertical joining lines to each board. Finally, measure the length of the transom and use scrap boards to create a template for making caps for the tops of the trusses.
To attach the crossbar to the rafters, overlays from sections of inch boards are used
After the template is lowered to the ground, it is disassembled and cuts are made according to the applied markings. In addition, a separate pattern is constructed according to which the ends of the rafter legs will be cut. The manufacture and assembly of hanging rafters is most often done below, lifting the finished structures onto the roof. If the weight and dimensions of the assembled trusses do not allow them to be pulled up manually, then the assembly is carried out on site. In this case, the components of the rafter system are fixed with nails ranging in size from 100 to 200 mm.
How to install rafters on a roof
In order to lift and install the trusses, you will need the help of at least one person. Trying and plumbing the rafters alone is an extremely difficult task - you will have to attach them to the struts more than once and descend from the roof many times to check the deviation from the vertical plane.
With the help of a rafter tooth, it is possible to obtain such a reliable connection that only one nail can be used for final fixation
When lifting the assembled rafters upward, first mount the outer structural elements, and then the central and intermediate ones. To strengthen the structure, a support is installed under each leg:
Having aligned the hanging rafters to the level, they are fixed with temporary spacers. After this, the lower ends of the beams are nailed to the matrix or floor beams.
Various temporary structures significantly simplify the process of installing rafters at level
There is no need to resort to newfangled methods of fixation using various corners and perforated plates. The reliable “old-fashioned” method of fastening using nails 200 mm long or construction staples will be much better both in terms of strength and reliability, and in cost. At this stage, you don’t have to worry about the structure looking flimsy.. After the remaining elements of the rafter system are installed and the sheathing is completed, the structure will acquire the necessary rigidity and stability.
Video: making and installing hanging rafters with your own hands
Features of installation of layered rafters
The process of manufacturing and installing layered rafters is generally very similar to the construction of a suspended roof frame. The main difference is at the top point and is due to the fact that the tops of the layered beams rest on the ridge girder. In this case, the connection with the latter is performed in several ways:
- simple adjoining apart (in parallel to each other);
- with making a vertical joint (the same as when connecting the paired legs of a hanging truss);
- by tightly fitting the beams to the upper beam (using a vertical cut or notch).
If the design of the wooden frame provides for the support of trusses on the side purlin, then the rafters are connected end-to-end, and in the places adjacent to the purlin, recesses are made.
To fasten layered rafters, use nails, construction staples or linings made of wood and metal
To ensure structural strength, the notches should not be too deep. Experts recommend making recesses no more than a quarter of the thickness of the timber or a third of the width of the board.
Individual developers most often resort to installing rafters in the following way:
- the upper part rests on the ridge beam through a vertical cut;
- From below, the rafter legs are held in place by a corner notch.
It is convenient to use a construction square for marking. After the scale is selected, on the sides right triangle the values of the rise of the slope and half of the span are set aside. Thanks to this, it will be possible to obtain the slope angle of the slope without resorting to mathematical calculations.
To make rafters, we suggest using the most convenient method:
At first glance, this method is very tricky. However, even a quick glance at the instructions provided is enough to master it perfectly. Of course, you can set aside the necessary distances and make markings using a calculation method, but it will be much easier to get confused when calculating angles and distances.
It should be remembered that the cuts made in the rafter legs must be absolutely identical, otherwise the roof slope will be uneven. For this you can use wooden block as a template. It is only important that its thickness does not exceed 1/3 of the thickness of the workpiece.
For the most common slope angles, there are templates, the configuration of which has already been calculated by professionals. By using one of these patterns, you can significantly simplify the task of marking the corners of notches.
Templates with marked notch angles allow you to simplify the process of making rafters
Assembly and installation of a layered structure
Video: installation of rafter legs of a layered roofing system
Methods for connecting rafter joists
When choosing timber for large roof trusses, you have to look for a reasonable compromise between the length and thickness of the rafters. The reason for this is the features of the standard range of lumber, in which longer beams have an increased cross-section. On the other hand, their use is not always justified both technologically and due to the increased cost of the structure. The way out of this situation is to lengthen the rafter legs by splicing. The rigidity and mechanical strength of the beam depends on how correctly the joint is made, so the connection is made strictly according to a certain method.
Oblique cutting method
The method of splicing with an oblique cut is that inclined cuts (cuts) are formed on the mating parts of the beams. They should be carried out especially carefully - after combining both parts of the beam, there should be no gaps left, otherwise deformation will appear at the junction.
When splicing with an oblique cut, there should be no gaps or gaps between the mating surfaces, which could weaken the rafter and cause its deformation.
When making cuts, leave a small transverse section with a height of at least 15% of the rafter thickness - the presence of the end part will make the connection more durable. To calculate the optimal length of an oblique cut, it is necessary to multiply the height of the beam at the cutting site by two. The truss is fastened with nails, clamps or bolted connections.
Connection by rallying
To lengthen the rafter using the joining (stitching) method, the edges of the boards are overlapped and a stand is installed in the center of the junction area. The elements are fastened using nails, which are driven in according to a certain pattern:
- along the edges of the ends - every 45–90 mm;
- along the edges of the sewn boards - in a zigzag pattern, in increments of 50 cm.
Connecting boards by joining allows you to do without additional pads, but requires the installation of additional support in the center of the junction area
In order for the beam to successfully cope with operational loads after joining, the length of the joining section (T) is calculated using the formula T = 0.42 × L, where L is the length of the overlapped span.
Frontal support
The connection by frontal extension consists in the fact that the edges of the individual parts of the rafters are carefully trimmed and butted together. For fastening, lumber linings with a thickness of at least 1/3 of the section of the main beam are used. The length of the overlays is determined by the formula L = 3 × h, where h is the width of the board.
When splicing with a frontal stop, a monolithic structure will be obtained only with the correct placement of fasteners
All parts are fixed using nails or bolted connections. In the first case, nails are driven in two parallel rows, trying to place the fasteners in a zigzag pattern. The threaded connection is made in a checkerboard pattern, determining the number of bolts depending on the length of the linings.
Composite length extension
To build up a rafter leg, it is not at all necessary to use both parts of the same section. With a composite extension, a single element can be lengthened by using two boards that are sewn onto its side planes. The resulting gap is filled with scraps of lumber of length l = 2 × h in increments of L = 7 × h, where h, as before, is the thickness of the element being extended.
Composite extension of rafters allows you to attach crossbars, supports and other structural elements in the most convenient way
Expert advice on making rafters and assembling roof frames
Getting started independent design and installation of the rafter system, be sure to consult with experienced roofers regarding the specifics of roof construction in your area. Perhaps their advice will save you from trouble and help you save time and money. In turn, we offer several recommendations that will help make the structure more reliable and durable:
- If a beam of minimal cross-section is used to make the mauerlat or top trim, then cuts can weaken it. For this reason, cutouts should only be made at the lower ends of the rafter legs.
- To prevent precipitation from falling on the wooden frame and walls of the house, the roof must have an overhang. To equip it, use pieces of timber (fillies), which increase the length of the rafter legs, or make trusses of increased size.
- Connections using cuts at an angle of 90 o cannot be used.- in this case, the resistance of the element to load forces is significantly reduced.
- If the elements of the rafter system are connected with threaded fasteners, then wide washers or metal plates are installed under the heads of the bolts and nuts. Thanks to the increased area, the fasteners will not be pressed into the wood.
- All wooden parts of the structure must be thoroughly impregnated with antiseptic and fire retardant.
- When determining the cross-section of the puffs, they are guided by how close they will be to the ridge. The shorter the connecting beam, the greater the load it bears and the more powerful the lumber and bolted fasteners are used.
- When determining the cross-section of the timber for the manufacture of rafters, do not forget to take into account the thickness of the thermal insulation layer.
Video: recommendations from experts on the correct connection of roof frame elements
https://youtube.com/watch?v=GbTAu5-flfsModern materials and technologies make it possible to build a roof of any configuration and purpose. Given such diversity, it is simply impossible to consider all options in detail within one article. However, based on the basic principles of construction discussed here, you can easily cope with the most complex structure. The main thing is to pay attention to detail, be attentive and careful in your work. And then the roof will not only be a reliable functional superstructure, but also a true decoration of your home.
Thanks to my varied hobbies, I write on various topics, but my favorites are engineering, technology and construction. Perhaps because I know many nuances in these areas, not only theoretically, due to my studies in technical university and graduate school, but also from the practical side, since I try to do everything with my own hands.
The construction of a rafter system is quite a complex and responsible task. However, you can do it yourself if you follow certain rules.
This article will talk about the elements of the roofing structure, as well as how to install rafters on the roof.
Before installing rafters on a gable roof, you need to find out what elements the roof structure consists of. It includes:
- Mauerlat. This is a beam that is rigidly fixed along the load-bearing walls of the building. For its manufacture, as a rule, a beam with a cross section of 15 by 15 centimeters is used. serves as the bottom and also evenly distributes the load created by the roof structure onto the walls of the building. Between load-bearing wall and the Mauerlat beam should contain a waterproofing material, for example, roofing felt. If the roof frame is made of metal, channels or I-beams are used as the Mauerlat.
- Rafter legs. They are the main element of the roof frame. Their size is taken in accordance with design calculations. The lower parts rest on the mauerlat beam, and the upper parts rest on the ridge beam. For their manufacture, regardless of the type of structure being built, it is recommended to use pine board section 150 by 50 mm or 200 by 50 millimeters.
- Run. It is a horizontally located beam that crosses the rafters perpendicularly along the entire length of the roof. There are three types of purlins in the rafter structure: side, ridge and mauerlat.
- Sill. It is a horizontal beam that is mounted on an internal load-bearing wall. This element serves as a support for the racks and evenly distributes the load they create. Lezhens install complex rafter systems. In other words, this roof element is not mandatory and is used when necessary.
- Puff. It is an element of a hanging rafter system. The tie forms with the rafter legs triangular truss. This element reduces the thrust force created by hanging rafters on the walls of the building. The location of the tie depends on the type of roof structure being built.
- Rigel. This element, like the tie, connects the rafters. The crossbar makes the structure more durable and stable. For its manufacture, timber with a cross section of 10 by 15 centimeters is usually used. The crossbar, in contrast to the tightening, is subject to compression rather than tensile load.
- Racks. It is a beam installed vertically. Used if the width of the building is large enough. This element strengthens the rafter system from the inside. Purlins supported by struts are installed on the racks.
- Struts. They are inclined beams supporting horizontal elements. The struts strengthen the truss structure and resist distortion and compression of the roof structure.
- Roof overhang. This is part of the rafter legs, protruding beyond the external walls of the building by approximately 40 centimeters. The overhang protects the external walls of the building from rain and melt water rolling off the roof.
- Fillies. It is a piece of board. Used to lengthen the lower part of the rafter leg.
Tools and materials
The roofing structure should be made of coniferous wood. The moisture content of the wood used should be less than two percent. Before use, the material must be treated with special protective agents.
For the manufacture of hanging rafters and tie rods, they are made from first grade wood. Rafter legs are made from first and second grade wood. Third grade wood can only be used for making struts and racks.
The strength of the roof structure depends on:
- Reliability of connections;
- Quality of the material used;
- The accuracy of the calculations performed.
Before placing rafters on the roof, you need to prepare the following tools and materials:
- Axe;
- Hammer;
- Level;
- Fastening elements;
- Waterproofing material;
- Boards;
- Pencil;
- Chainsaw;
- Electric drill;
- Drill set for electric drill;
- Nails or screws;
- Roulette;
- Cord.
To make footrails, timber or edged boards are used. Wood elements should be treated with bioprotective and fire retardant materials.
Before installation, you must select the type of ridge connection and the method of attaching the rafters to the beams or mauerlat.
Calculation of rafter pitch
This issue needs to be given special attention, because the strength of the roofing system depends on their cross-section.
When calculating the distance between the rafters, permanent and temporary loads on the roof being erected should be taken into account. The following elements create a constant load:
- roofing material;
- rafter system;
- roofing cake (vapor barrier, insulation, waterproofing);
- finishing elements for an attic or residential attic.
- the weight of the worker performing roof repairs or maintenance.
To perform calculations (section and pitch of rafter legs), theoretical knowledge as well as practical skills are required. You can determine the approximate parameters of the roofing structure using the following table:
When choosing a rafter pitch, you must consider the type thermal insulation material. It is important to remember that the span between adjacent rafters should be 10 - 15 millimeters less than the width of the cotton insulation.
Also, when choosing the distance between the rafters, it is necessary to take into account the recommendations for laying the selected roofing material.
Types of rafter system
There are two types of rafters: hanging and layered. Each type will be considered separately.
Hanging
Hanging rafter systems are used in cases where the house does not have internal supports (columns, walls). This structure is supported by external supporting walls.
In this case, the rafters work in compression and bending. exert a bursting force on the outer walls of the house. To reduce it, use a puff.
The puff is made of wooden beams or metal. Its location depends on the design of the roof being built.
For example, when building a roof mansard type the puff is placed at the base. In this case, it acts as a floor beam. The higher the tie is located, the greater the load on it.
A hanging rafter structure is used if the distance between the supports is less than 6.5 meters. To make these rafters, boards, logs, or beams are used. To connect elements to each other, use:
- steel profiles;
- cuttings;
- bolts;
- nails;
- pins.
Layered rafters
Rafters of this type are used in buildings with a solid internal wall. These elements are usually made of wood.
The support for the layered rafter system is provided by internal elements (column, wall). This is their main difference from layered rafters.
Rafters of this type work only for bending. Layered rafter structures are more cost-effective and lighter in comparison with hanging ones.
How to install rafters on a roof
Installation of gable roof rafters consists of the following steps:
- Making a truss template. It is necessary to lift two boards onto the ceiling, and then connect them together at one edge using nails. Next, you need to install the free ends of the boards on the support beam and fix the angle between the boards. To do this, you need to nail the crossbar. Then you need to lower the resulting template onto the support beam and mark the cutting angle of the rafter legs with a pencil. It should be noted that the strength and reliability of the entire roofing structure will depend on the quality of the template.
- Lower the made template down and begin making the rafters. The template must be fastened well so that when lowering it the angle between the rafters is not broken. The first manufactured truss is lifted onto the building and installed on the base.
- Mark the cut location on the mauerlat and rafter legs and make the cut using a chainsaw. Next, you need to start assembling the next truss.
- Install the first two trusses on the mauerlat beam along the edges of the building. The rafters installed along the edge of the mauerlat beam are secured on both sides with the help of supports. Then pull a cord between them to determine the level. Rafter trusses must be installed perpendicular to the base of the floor.
- The remaining trusses need to be assembled after the level has been set and all fasteners have been checked. The rafters will not move if two boards are hammered between them. Next, you need to secure the cross bars and supports.
- Install a vapor barrier, heat insulation and waterproofing layer. The roofing material is attached to the sheathing. Its pitch depends on the selected roofing material.
This video explains how to install rafters on the roof:
Housing construction today is so diverse that sometimes the structures being built take on a completely bizarre, fantastic look. In particular, architects like to experiment with the roof, which is made transparent, and in the form of tree foliage or a flower, and a platform for skateboarding - in general, their imagination is completely limitless. But somehow we are closer simple options, for example a gable roof. We’ll talk about what it is and what the rafter system of a gable roof consists of in this article.
It is this type of construction that is most popular in the construction of residential buildings, since it creates sufficient attic space that does not require additional insulation. In addition, a gable roof is not as difficult to install as, for example, a hip roof, and also does not require huge investments for its installation.
A gable roof is a structure consisting of two rectangular planes connected at the top to each other, and at the bottom to the walls of the house. The end part of such a building is usually built from the same materials as the walls of the building; sometimes the entrance to the attic is built here.
Recently, it has become very popular to build an additional room in the attic space, often used as a summer guest room. Installation of a gable roof rafter system and subsequent insulation of the resulting room allows you to create a full-fledged room in which you can live both in summer and winter.
All the advantages of gable structures
Main components The rafter roof consists of a mauerlat and rafter legs; in addition, various struts, racks, crossbars, stops and battens help make the structure strong and reliable. The drawing of a gable roof also includes a layer of insulation, vapor barrier, waterproofing and the roof itself. Thanks to all these elements, a gable roof has a number of advantages:
- simplicity of technical execution;
- low probability of leaks, since the structure is one-piece;
- high efficiency, because a relatively small amount of materials is spent on its construction;
- the possibility of arranging a full-fledged living area in the attic;
- ease of repair in case of defects;
- high strength and wear resistance.
The angle of inclination is an important component of a durable roof.
The magnitude of the inclination angle is determined depending on weather conditions region of residence, the characteristics of building materials and architectural requirements.
For example, in areas where loss large quantity precipitation is normal, the roof is always built at a large angle. This is necessary to ensure that snow masses accumulate on its surface as little as possible, which could lead to the collapse of the building. In regions with strong winds, flat roofs are most often built, since the wind pressure on such structures is significantly reduced.
Whatever climatic zone there was no dwelling, the rafter system of a gable roof cannot be built at an angle of less than 5 degrees!
Recommendations for calculating the area of a gable roof
Calculation of roof area - picture Carrying out the calculation is not as difficult as it might seem at first glance, but this painstaking process requires perseverance - all data must be double-checked at least three times. Agree, no one wants to spend money on completely unnecessary building materials.
In some cases, measuring the roof area may be complicated by certain “obstacles”, for example, the presence of an attic or unusual shape roofing – it’s unlikely to be possible without the help of a specialist. We will consider calculating the area for classic version roofs with two slopes:
- First, we determine the length of each slope; it is equal to the distance between the lower edge of the ridge and the extreme point of the cornice;
- We take into account all elements of the roof: parapets, overhangs, firewalls and other structures that create additional volume;
- We decide on the type of roofing material for which we will calculate the area;
It should be taken into account that in the case when the roof is covered with rolled or tiled materials, the length of each slope will be reduced by about 0.7 m.
- We do not take into account elements such as ventilation shafts, windows and chimneys;
- When the area of each slope has been calculated, taking into account all the details, we calculate the slopes: we multiply the elements of the slopes by the cosine of the angle of inclination of the roof, and calculate the area only by overhangs.
For the greatest convenience of calculation and obtaining correct data, it is best to calculate the area of each element separately, and then add the resulting numbers.
The roof area has been calculated, the roof has been decided on - all that remains is to understand in detail all the structural elements, such as rafters, mauerlat, side/ridge girders, struts and braces, as well as diagonal braces, after which you can begin to calculate the specific type of rafter system.
Hanging and layered rafters
Of course, such a structure as a do-it-yourself gable roof rafter system appears in the minds of many as something very complex and labor-intensive. But if you carefully consider the construction of such a structure and study in advance required material– the only question will remain in the “number of hands” you will need for the construction process.
Let's start with such a component of the roof as hanging rafters. These beams have only two points of support - the walls, so the main loads acting on them are bending and compression. The weight of the roof, as well as the action of snow and wind, is transferred to the walls through the hanging rafters, so that this pressure is compensated, the rafters are connected with a tie made of metal or wood. It can be placed at any height, but the higher it is, the stronger and more durable it should be.
Layered rafters are beams that have an intermediate support resting on interior wall Houses. The main effect on such a structure is bending. The supporting structure of the roof is made only of layered supports, when the distance between them is no more than 6.5 m.
The same roof can consist of layered and hanging rafters at the same time: where there is an intermediate support, layered rafters are erected, and where there is not, hanging rafters are erected.
Mauerlat and purlins
The lower part of the rafters in houses built from timber rests on the upper crown, and in buildings made of brick or foam concrete - on a special beam called a mauerlat. To lay it, a waterproofing material is placed along the inside of the load-bearing wall, on which the Mauerlat rests. The length of the beam can be equal to the length of the building wall, or it can be adjusted to the size of each rafter leg - this is even more economical.
Ridge purlin is a beam to which the upper parts of the rafters are attached. That is, this is the ridge of the roof. Its length depends on the length of the roof, so both a solid mass and several logs are used for its construction.
Side purlins are needed for additional support of the rafters; their emphasis is also placed on the gables of the building. The ends of such purlins are sometimes extended beyond the gables, thus creating unloading consoles, as a result of which the roof pressure on the central part of the purlin is significantly reduced.
If the roof of a building is erected from heavy materials, for example from natural tiles, then the side purlins are made in the form of a rocker arm, for this purpose the logs are slightly hemmed and bent.
A little more about the important elements of the roof
Diagonal overlaps - picture Additional diagonal ceilings are called braces, with the help of which the rafter system of a gable roof is strengthened and the wind resistance characteristics of the gables are increased. The upper part of the braces rests against the gables, and the lower part against the central ceiling.
Struts are necessary to reduce the load on the rafters; installing them at an angle of 45 degrees or higher can significantly reduce wind loads and snow pressure on the roof, so in the northern regions of the country such roof elements are simply irreplaceable.
If the roof consists of slopes of different sizes, then their angle of inclination will not be equal. Consequently, for the greatest strength of such a structure, vertical posts are erected at the “fracture” points, on which the side girders rest. Most often, such structures are built for attic spaces.
In areas characterized by constant strong wind, rafter systems are necessarily strengthened with diagonal ties, which are boards whose thickness is from 25 to 50 mm. The lower edge of the board is attached to the heel of the rafter leg, and the upper edge to the middle of the opposite rafters.
Correct calculation of materials for the rafter system of a gable roof
You should not be afraid to make all the necessary calculations yourself, because the dimensions of a gable roof, especially if it has the shape of an isosceles triangle, can be calculated by anyone without deep mathematical knowledge.
So, let's look at the calculation of the rafter system for a gable roof using a specific example. The house for which it is necessary to build such a structure has a width (W) of 4 m, a length of 6 m, and the angle of inclination of the rafters (U) should be 120 degrees. The roof will be constructed from metal tiles, the distance between the rafters is planned to be 1 meter.
First, find the height of the central support (C):
C = 0.5? Width / tgY/2 = 0.5? 4 / 1.73 = 1.2 m
The length of the rafter leg (Ds) is calculated using the following formula:
Ds = 0.5?Wir / sinY/2 + 0.5 = 2.8m
0.5 in this formula is the allowance for the roof canopy, it must be taken into account without fail!
Roof area (Pk) = D? Ds? 2 = 33.6 m2
It turns out that this is exactly the number of sheets of metal tiles you will need for the roof.
Let us conditionally take the distance between each lathing plank (Рп) as 35 cm, which means:
Sheathing length = Ds / Rp? D?2 = 96 linear meters
With a house length of 6m and a distance between the rafters of 1m, we will need 7 rafter legs, which means the amount of timber for them and for the mauerlat is needed no less than:
Length of beam = (2 ? Ds + Width + C) = 75.5 l.m.
The required amount of other materials is calculated in the same way. When all the calculations have been made and the required amount of building materials has been purchased, we proceed to the actual construction of the gable roof.
We build a gable roof with our own hands
So, now we have come close to the moment of installing a gable roof rafter system. This process begins with the construction of beam floors.
There are only two options for their installation:
- If the attic space is not planned to be used as housing, then boards measuring 50? 150 mm.
- To equip the attic you will already need timber with dimensions of 150? 150 mm, and each of them is laid exactly on the load-bearing walls of the building. This is the only way to create a truly reliable and durable attic structure, only the cost of its construction will be an order of magnitude more expensive than the construction of a conventional attic. But the living area of the house will increase significantly - decide what is more important to you and think through everything to the smallest detail.
Floor beams are laid across the entire width of the building, leaving 500-600mm per projection from the load-bearing walls - this will protect the wall from water flowing from the roof slopes. Along the entire perimeter of the house, a board is laid on beams, which will become the basis for the wall racks of the second floor - the attic.
For the construction of all roof elements, the following fastening materials are used:
- screws,
- nails,
- screws,
- dowels,
- wire,
- metal squares.
Once the racks are installed, you can begin arranging the rafters.
This do-it-yourself gable roof rafter system is the simplest in technical design. Why? Firstly, because there is no need to calculate the structure of the rafters depending on the material and location of the insulation.
And secondly, we don’t need cross-sectional dimensions either.
The easiest way is to “tame” a gable roof of a regular triangular shape, because all its components will have identical dimensions.
In addition, this system has several more undeniable advantages:
- the cross-section of rafters and beams has a high margin for load-bearing capacity;
- this form is very reliable, since the load on the structure is distributed evenly, and the risk of deformation of the rafter legs disappears;
- the triangular rafter system is an independent structure, so if problems occur in other elements of the building, it remains undamaged;
- the beam, laid with a slight protrusion, also serves as a frame for the entire weight of the roof - and this is additional reliability of the entire building as a whole.
Attic rafter system
We will only talk about a one-level attic, since it is quite possible to build it with your own hands. Construction of more complex structures It is recommended to entrust it to experienced specialists, since you can easily make mistakes in calculations without their help, and the result will be disastrous.
A board is placed on the beam, from which it is sawed off Bottom part- this is done to ensure that there are no gaps between the beams and rafters.
You need to lay a beam on a board (100 mm) and draw a line where they join. Then the board must be sawn along this line, resulting in a beveled board that will fit snugly against all floor beams.
Again, along this line we make a cut and so on. Completing these steps will ensure tight and precise fastening of the upper part of the rafter system, the installation of which can begin. Using the overlay, secure each row of rafters at the top (on the ridge); finally, fasten the resulting strapping with a special crossbar, which will act as a ceiling for the ceiling.
The rigidity of the structure being built directly depends on how firmly the rafters are fastened to each other. It is best to use special metal linings - this way you can achieve the greatest strength of the roof.
When all the rows of rafters are fixed, you can begin checking the correctness of the creation of the pediments - they must be positioned strictly at right angles. This is where a plumb line comes in handy - an indispensable thing for such situations.
When the correctness of the design does not raise any doubts, you can begin to completely secure all the parts together, this will help soft wire, nails or staples.
Now you need to stretch the twine along the top point of the gables, this will make it more convenient to install the middle rafters at the same level.
To eliminate the possibility of sagging of the rafter system, it is necessary to strengthen the middle rafters with special struts.
Installing struts usually does not cause any difficulties: their lower part is attached to the attic post, and the upper part is attached to the middle of the rafter leg, where you need to cut out a groove of the required depth. To secure the structure, you need to choose nails from 200 mm.
That's all - the rafter system for a gable roof with your own hands is ready! All that remains is to build the sheathing and cover the roof with a roof, but these are completely different technologies, which will be discussed in the next article.
The roof is complex and responsible architectural element any building. Its construction should be treated with special attention; it must be remembered that the installation of a rafter system requires considerable experience in performing such work and special tool. Those who are holding carpentry and measuring tool– the results of activities can be very negative.
There are two types of roofs depending on the number and placement of rafter support points, but each developer can, at his own discretion, slightly change the specific design of the rafter system. This takes into account the operating conditions of the building, the purpose of the attic space, the climatic zone of the location, and the technical parameters of lumber and roofing coverings. Of course, the type of rafter system is influenced by the personal experience and preferences of developers.
Before you start making rafters, you should decide on their type, method of fastening and linear dimensions. Only in this case can you be sure of the strength and safety of the structure.
How do various factors influence the parameters of rafters?
| Physical factor | Brief description of the effect on rafter parameters |
|---|---|
| The rafters must withstand snow and wind loads. During calculations you need to take from the tables building codes and actual rules maximum values snow cover, take into account the strength and wind rose. The data allows you to find out the total load on the roof slope depending on its area and angle of inclination. Next, you can determine the size of the rafters, their number and pitch. In this case, a safety factor must be included. The fact is that lumber does not have stable and uniform strength values; too many unforeseen factors influence these indicators. For most cases, 50×150 mm or 50×200 mm boards are used to make rafter legs. |
| Gable roofs can be layered or hanging. For hanging roofs, you need to make rafters from stronger boards. In this case, the method of fixing the elements to the Mauerlat is taken into account. If a notch is made, then the width of the boards should increase by the amount of the notch. The fact is that the cut in this place automatically reduces the width of the material that takes the load. If you make a cross cut 60 mm long on a 200 mm thick board, then only the remaining width of 140 mm is taken into account. Accordingly, if, when calculating the loads, rafters from 200 mm boards are selected, but during fastening unintended cuts of 60 mm are made, then the width of the blanks for the rafters increases to 260 mm. This remark is made for those who like to abuse various notches and cuts for the persistent areas of the ends of the rafters. Currently, there are many special devices that allow you to firmly fix the rafter in the desired position without sawing. |
| For residential buildings, rafters must have a safety margin of at least 1.4 of the design values. For non-residential buildings the coefficient is reduced to 1.2. Conclusion - the size of the rafter boards on houses is larger than on garages and other extensions. |
| Residential attic spaces(attics) must have an insulated roof. The width of the rafters must correspond to the thickness of the insulating layer. At the same time, you need to adjust the pitch between the rafter legs depending on the standard width of the insulation. If in a given climate zone optimal thickness roof insulation is 200mm, then it is recommended to choose the same width for the rafters. Various extensions of narrow rafter legs during roof insulation are not considered the right solution. |
This knowledge will help you accept right decisions both during the manufacture of the rafters and during their fixation directly in place. Mistakes in the construction of a rafter system are too expensive; you should not be overly self-confident.
What influences the choicesizes andwaysfasteningsrafters
Very important point. The task of any fixation is to ensure the stability of the connection node, while it can be stationary or have one or more degrees of freedom. This cannot be achieved without knowledge of the loads affecting the rafter legs. Loads can be permanent and temporary, dynamic and static, unidirectional and multidirectional.
- Constant vertical forces. They arise due to the impact of roofing and roof insulation materials. Due to the fact that the rafter legs are located at an angle to the vertical force, they are subject to bending and expansion loads. The magnitude of the forces is determined after constructing the diagram; based on the specific bending and expansion forces, the thickness and width of the boards for the rafters is selected. The fastenings must prevent the rafter system from spreading.
- Variable vertical forces. Appear in winter, the magnitude depends on the depth of the snow cover.
- Lifting wind forces. As a result of gusts of wind, lifting forces are applied to the roof. The dimensions of the rafter legs are not affected; the forces are taken into account only when choosing the type of fixation; it must provide for and support such loads.
- Lateral forces. The value depends on the windage of the roof. As a result of gusts of wind, lateral forces act on the rafter system. They increase bending and tearing loads. This feature also needs to be taken into account during the manufacture and installation of rafter legs.
Rigid mount options available roof trusses, metal plates, corners, screws and nails are used for this.
Sometimes it is necessary to use floating rafter connections to compensate for changes in the size of wooden houses. For floating connections, special fasteners and bolts are used. The second allows the rafter legs at the top to rotate slightly.
Another example of a loose rafter connection is a sliding one. It is used on wooden log houses and makes it possible to compensate for the natural shrinkage of the house.
What elements are used to increase the stability and load-bearing capacity of rafters
As a result the right choice rafter system and methods of fixing its elements, the structure must be stable, compensate for natural fluctuations in linear parameters and withstand various loads that arise during operation. To fulfill the conditions during fixation of rafters, they can be used additional elements fixation.
Runs
Most often they are mounted in the ridge part of the system; the upper ends of the rafter legs rest on them. To increase stability, cuts may be provided. The top connection is rigid or floating with bolts. On large roofs, purlins can be installed in the middle of the rafters or in other places with critical loads.
VertikAlinen racks
They are installed to strengthen rafters; through the use of racks, elements can be made from thinner lumber. Vertical racks the upper end rests against the rafters, and the lower end against the beam or ceiling beams.
CornerOpores
Resists bending and expansion forces, universal use. Corner stops can be placed in any place on the rafter leg, raising concerns in terms of strength. Due to such stops, the resistance of rafters to bending and tearing forces significantly increases.
Puffs(crossbars)
The purpose is to keep the rafter legs from spreading; they are used on hanging rafter systems. Most often they are placed in the upper part of the truss; for manufacturing, you can use boards approximately 20–25 mm thick. The fact is that they work in tension, lumber holds such forces well. The boards do not work well under compression, quickly sag and lose their original strength.
Knucklehellish
They are used in the upper ridge part of the rafters; due to the use of puffs, the strength of the joint connection is increased. Pulls can be made of wood, plywood, OSB or metal.
Lugs(stops)
They have many specific names. They are ordinary pieces of boards 30–40 cm long and 40–50 mm thick, fixed at the bottom of the rafters. They rest against the mauerlat and prevent the structure from slipping. The use of bosses allows for a rigid connection of elements without sawing down the rafters. We talked about the problems that arise in connection with sawing in this article above.
Prices for various types of timber
Options for connecting the ridge assembly of rafter legs
The ridge is one of the main and most loaded elements of the rafter system. The unit has several connection options; you should choose a specific one depending on the general parameters of the roof.
If the slopes are long, it is better not to use a ridge beam, but instead install two parallel purlins and tie-down crossbars. This design is easier to make, more stable and safe.
For a suspended roof, you should choose the most reliable methods of connecting rafter legs; these systems have a minimum number of additional stops.
Prices for various types of fasteners for rafters
Rafter fasteners
Step by stepWithThand of mouthAnew rafters
For the rafter legs, 50×200 mm coniferous boards and first-grade lumber are used. The boards cannot have traces of rot or fungus, significant defects or deep cracks. The use of low-quality lumber for the manufacture of rafter systems is strictly prohibited.
To increase the protection of roof elements from rotting, it is recommended to use fire protection.
Rafter blanks should be impregnated at least twice, and the material should be dry and clean. Processing is done on a level area in dry and clear weather.
You can impregnate with a roller, brush or pneumatic remote control. It is not recommended to use household hand sprayers - they are too time-consuming and difficult. The boards can be raised to the top after the impregnation has completely dried.
Our gable roof has a ridge girder; the vertical supports rest against a beam located on the load-bearing wall in the middle of the building.
Practical advice. If the house is quite tall and the boards are heavy, then it is recommended to make a simple device to protect the window openings from damage. To do this, two boards are knocked together in the form of a square; the length and width are selected taking into account the parameters of the opening. The device is installed on the window sill, and the rafter boards do not damage the foam blocks during lifting.
Prices for fire-bioprotective impregnations
Preparatory operations
The production of rafters begins with preparatory operations.
Step 1. Raise rafter boards into the attic. For convenience, place them evenly along the length of the building, place one end on the mauerlat, and the other on the girder. First you need to install the outer rafters on both sides of the roof of the house, stretch a thread between them and install and align all the remaining ones along it.
Step 2. Check the position of the ridge run again. It should be located exactly in the middle of the roof. Its displacement by 1–2 centimeters will not affect the strength of the roof as a whole, but will somewhat complicate the manufacture of rafters and installation roofing materials. Besides, experienced builder may notice a discrepancy in the sizes of the slopes and, accordingly, the asymmetry of the roof. It is recommended to ensure that the ridge run is located along the line of symmetry, unless this is associated with great difficulties. The final decision is made by the foreman on site and depends on the magnitude of the displacement and the amount of work to correct the error.
How to align a run?
- Attach a sheathing board to the mauerlat; it is lighter and easier to lift and fix. The second end should lie on the purlin. The board is nailed to the mauerlat with an ordinary smooth nail or screwed with a self-tapping screw.
- Climb to the top of the purlin and use a tape measure to check the distance from the edge of the purlin to the mauerlats installed on opposite walls. Work very carefully, it is advisable to use insurance. Unfortunately, in practice, few people follow safety rules, but in vain. Falls from height can cause very serious injuries.
- Center the purlin and secure the board. To increase rigidity, fix the same board on the other side of the purlin.
Now everything is ready, you can begin to manufacture and install the rafters.
Installationrafter legs
If you work alone, then you need to screw a piece of lath to the purlin at the place where the first rafter is fixed. The rafter board will be temporarily fixed to it to prevent it from sliding down.
And at this time, you can carry out work on the manufacture and preparation for connecting the upper part of the rafters.
Step 1. Lift and place the rafter board in place, using a clamp, clamp it to the previously attached batten.
Step 2. Draw lines to cut out the stop pad. This is done in two stages. First, draw a horizontal line. To do this, press the rail, square or other flat object tightly against the horizontal surface of the purlin.
Second, draw a vertical line. Now the ruler or square should be pressed against the side surface of the purlin.
Important. The width of the ruler should be no more than 2–3 cm, there is no need to make deep cuts and significantly reduce the width of the rafter leg, it loses its maximum design strength.
Make the same markings at the bottom of the rafters. Only now the ruler needs to be pressed against the surfaces of the Mauerlat.
Step 3. Remove the board and carefully cut out the seats. You can work with a hacksaw or an electric circular hand saw.
Practical advice. If the cuts are made with an electric circular saw, then it is better to cut in two steps. First cut to the mark, then turn the board over and cut again to the mark. Use a hammer to knock out the cut piece, and remove the remaining protrusion with a chisel or chisel. There is no need to go beyond the line with the saw and try to cut off the lip in one go. This method increases the cut by 3–5 cm, depending on the diameter of the disk, which significantly reduces the load-bearing performance of the rafters.
Step 4. Place the prepared rafter in place and check that it is made correctly. Perform the same operations with the second leg of the truss.
Step 5. Place the rafters with emphasis on the mauerlat and purlin, tighten them with a clamp at the top. Find the middle of the purlin and transfer the line to the rafters, use a level or a construction square (only when the plane of the purlin is strictly horizontal).
Step 6. Saw two rafters along a vertical line at the same time. The boards must be tightly clamped with a clamp. Pay maximum attention to ensure that the saw blade is perpendicular to the plane of the rafters. If you saw it obliquely, the ridge joint will not fit tightly, and this reduces the stability of the rafter system and is considered an obvious construction defect.
If there is a lack of practical experience in performing such work, the first leg may have a gap in the ridge part; if it is within 1–2 mm, then there is nothing to worry about. If it is more than 4 millimeters, then the element needs to be corrected. Look at which planes of the thrust pads do not allow the top cut to fit tightly. Approximately indicate the size of the additional cut. Remove the rafters and remove any interfering protrusions. Check the connection again, if gaps remain, repeat the operation. As practice shows, experience appears on the second or third rafter and no further corrections need to be made.
Step 8 Securely fasten the rafter legs in the correct places. To do this, it is recommended to use metal plates and corners; working with them is simple and easy; their strength fully meets the requirements for the rafter system.
For each pair of rafters you will need one large reshaped plate to connect the ridge assembly, two 50x50mm corners for fixing to the purlin and two 60x80mm corners for screwing to the Mauerlat. The thickness of the metal is at least two millimeters.
In the same way, install the outer rafters on the other side of the house, stretch the threads between them. One at the top and bottom and one in the middle. To prevent them from interfering during the manufacture of rafters, make a gap of about one centimeter between the thread and the plane.
Real professionals never make one rafter in the attic of a house. This algorithm of work significantly increases construction time, complicates the process itself and makes it unsafe. Working with electric tools on unsuitable sites is very dangerous; injuries from them are severe and often cause disability.
If the house is built with high quality and strictly adheres to the dimensions and rules, then the rafter legs are made according to one template on the ground. The finished elements are assembled on the roof. This technology increases labor productivity by 3–5 times, while at the same time improving the quality of the rafter system, it is more reliable and durable. Of course, the salaries of builders also increase proportionally. They work from the mine and receive money not for the time spent in the attic, but for the assembled roof.
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Video - Manufacturing and installation of rafters on a gable roof