In Moscow construction, two fundamentally different types of roofs are used: attic-free and attic, and attic-free roofs are used in two design varieties - unventilated (Fig. 7.1) and ventilated (Fig. 7.2).
Roofless roofs received mass use in five- and nine-story large-panel buildings. The most typical example is the combined roof design in the 1605 or I-464 series houses (see Fig. 7.1). The load-bearing base here is the same flat reinforced concrete slabs as in interfloor ceilings. Under construction conditions, insulation made of foam glass, cement-fibrolite boards, etc., a cement screed and a waterproofing carpet are laid on the load-bearing slab under construction conditions, along with a layer of vapor barrier. Drainage from the roof is organized through an internal drain.
This design is highly labor-intensive, since all work is carried out under construction conditions.
Ventilated combined roofs, the structure of which consists of twin iron concrete slabs with insulation enclosed between them (see Fig. 7.2, a), are manufactured in the factory. The drainage system here is also internal (see Fig. 7.2, b). Mineral wool slabs with a bitumen or phenolic binder are used as insulation, cement fiberboard etc. The lower and upper slabs are connected to each other using expanded clay concrete wedge-shaped ribs (see Fig. 7.2, a), thanks to which the necessary slope of the upper roofing panel is simultaneously organized.
What’s new in this design is the inclusion of a prefabricated valley element in the roof, which makes it possible to clearly organize the drainage of water from the roof to the internal drainage funnels.
The weight of a complex panel of this design is approximately 8 tons. It is used for nine-story large-panel houses of mass series II-57, II-49 and 1605/9. Surveys have shown reliable operation such a roof design has satisfactory waterproofing and thermal properties.
Attic roofs are usually made on high-rise buildings - more than 9 floors. Their designs are largely determined by the design of the house as a whole. At panel construction houses with a narrow pitch of transverse load-bearing walls, the roof is made of frequently ribbed vibro-rolled slabs in combination with a special prefabricated valley element, as was done, for example, on a 17-story building made of vibro-rolled structures built on Mira Avenue. In this case, the insulation is located along the ceiling above the upper residential floor, and the attic thus remains cold.
In houses with a wide pitch of transverse walls, the load-bearing basis of the attic roof is panels used in interfloor ceilings, or ribbed roofing sheets. In houses with longitudinal load-bearing walls, for example series I-515 or in brick houses, the roofing is carried out using vibro-rolled, frequently ribbed panels laid along special transverse girders (Fig. 7.3) or along long ribbed flooring.
Similar solutions for attic roofs have been implemented in all high-rise buildings, both large-panel and frame. The use of attic roofs helps improve the performance of residential buildings and, at the same time, is not associated with a significant increase in construction costs.
Let's look at the features of roof operation and compare existing roof design solutions.
The combined roof as an external fence differs from the external walls by the presence of a thick waterproofing layer (carpet) located with outside. The waterproofing layer is practically vapor-tight and creates conditions for moisture accumulation directly in the insulation layer under the waterproofing. Due to the diffusion of water vapor penetrating from the room, moisture is retained in the structure and as a result (during the operation of the building in winter) there is a sharp deterioration in the heat-protective qualities of the roof, delamination and damage to the waterproofing carpet, and destruction of the insulation. The situation is aggravated by the high initial humidity of thermal insulation materials - fiberboard, mineral wool boards and other porous materials that easily absorb and slowly release moisture. As field observations have shown, the actual humidity thermal insulation material after 2.5 years of operation it ranged from 12 to 28% instead of the standard 3-10%. Such high humidity The thermal insulation layer of combined roofs negatively affects their performance, reducing durability and increasing the thermal conductivity of structures, which causes freezing of the roof or the appearance of condensation on the ceiling of residential premises.
It is well known that with increasing moisture content of materials, their thermal conductivity increases significantly. For example, for foam concrete with a volumetric weight of 600 kg/m 3 the coefficient of thermal conductivity at a weight humidity of about 10% is equal to 0.226 kcal/m 2 ·h·deg, and with a weight humidity of about 20% it is already 0.321 kcal/m 2 ·h·deg. During the heating season, heat loss through 1 m2 of coatings increases by almost 30% with an increase in the humidity of foam concrete from 10 to 20%. This can be compensated by increasing heating (and correspondingly increasing fuel costs). But with increased heating with roofing panels with insufficient heat transfer resistance (due to high humidity) the sanitary and hygienic conditions of the premises are deteriorating, despite the increase in operating costs.
In addition, high humidity of materials under the roofing carpet dramatically reduces its durability. Due to the intense heating of the carpet in the summer, the water vapor pressure in the pores of the material underneath sharply increases, as a result of which easily breakable swellings are formed in the carpet, the height of which reaches 20-30 mm. This phenomenon becomes even more intense due to the occurrence of cracks in the wet cement mortar screed, which freezes and thaws repeatedly in winter.
A high initial moisture content is especially typical for non-industrial combined roofs, insulated by laying heat-insulating material on a load-bearing slab, followed by screeding and carpet gluing (as, for example, in houses of the 1605 series). It is difficult to protect structures of this type from being soaked by precipitation during the construction process.
As surveys have shown, ventilated roofs dry out quickly: after a year of operation, humidity decreases from 13% to the standard - 3%. Observations have shown that air movement in ventilated roofs occurs constantly; the speed of this movement, depending on the speed and direction of the wind, ranges from 0.08 to 1 m/sec or more.
In the process of developing and improving the designs of combined roofs, many different solutions have been developed, but until now the roofs still remain busy and lack reliable performance.
Among the heavy, non-industrial and at the same time expensive solutions for attic roofs is the roof structure in houses of the 1605 series. It is no coincidence that it turned out to be 18% more expensive and 2.5 times more labor-intensive than the design of a combined roof made of paired reinforced concrete shells (Table 7.1), in which normal temperature and humidity conditions are ensured. The latest solution has significantly improved the design of reinforced concrete rolling elements, which have become more crack-resistant and rigid; The element of the tray through which atmospheric water is diverted to the internal drains is successfully designed. All the main work on the installation and completion of the roof is carried out at the factory, and during construction they only seal the seams between the slabs and glue the last layers of the waterproofing carpet.
Drains from roofs are accepted as internal, since both organized and unorganized external drainage is unacceptable in the Moscow climate, especially in high-rise buildings.
A reliable and rational design of internal drainage has been developed, which can be recommended for widespread use (Fig. 7.4). The internal drainage is made of cast iron or, more rationally, of asbestos cement pipes with a diameter of 150 mm, connected by couplings. Its main feature is the organization of open outlets to the surface of the earth. Gutters with such open outlets have been operating reliably for more than 10 years.
Measurements of the temperature of melt water in the drain carried out in winter showed that it does not fall below -2° C, and therefore the possibility of the formation of ice plugs is excluded. Thus, traditional solutions with descent turned out to be completely unnecessary atmospheric waters from internal drains to systems storm sewer, which are not available everywhere and also lead to a sharp increase in the cost of drains (Table 7.2).
In order to avoid the formation of ice dams on the ground under an open outlet, it is advisable to switch the discharge of essentially a very small amount of melt water into the city sewer during the winter period.
The analysis shows (see Table 7.2) that the cost of installing internal drains with open system releasing water with immeasurably higher performance qualities is approximately equal to or lower than the cost of external organized drains.
Drainage funnels are usually located along the longitudinal axis of the building and one for each residential section. The maximum catchment area per drainage funnel should be no more than 400 m2. The transverse slopes of the roof, directed towards the axis of the building along which the drainage funnels are located, are usually 1.5-3%. Between the funnels, triangular inclined roof slopes, called envelopes, are formed, through which water flows into the funnels. In ventilated roofs, it is most rational to arrange straight gutters with a slight longitudinal slope of 1-1.5% (see Fig. 7.2, b). A waterproofing carpet consisting of four layers of roofing material on one layer of glassine is laid on the envelopes or in the gutter.
The correct design solution for various types of roof superstructures is important to ensure high performance qualities of roofs: ventilation ducts, hatches, etc. Currently, industrial solutions for superstructures have been developed, which simultaneously provide for reliable installation and fastening of the waterproofing carpet, in particular, the combination of ventilation ducts, sewer hoods and radio and television antennas in one block. Thanks to this, it is possible to significantly reduce the number of places where the roof intersects with superstructures and eliminate possible damage roll waterproofing, which occurs in areas near intersections.
Generalization of construction practice allows us to recommend an attic type of roof (with a warm attic) with an internal drain made of asbestos-cement pipes and water discharge from the drain at ground level as the main solution for residential buildings with a height of more than 9 floors.
In some cases (for example, if a metal tile system is being installed on top of old soft tiles), this is possible. However, it is necessary to understand that a damaged base can begin to rot and, thereby, provoke failure of the new layer. This is why we would not recommend laying new materials on top of old ones. It is better to remove the damaged building material and completely complete the required work, as required by technology.
As practice shows, the overwhelming majority of roofs in ordinary private houses are built in such a way that there is no need to dismantle the roofing base to install an additional insulating layer. If we talk about multi-apartment buildings, then the situation is different: since fused coatings are used in multi-storey buildings, insulation becomes impossible.
If there is damage to individual structural elements, then only these parts can be replaced. In this case, the area of damage should not exceed 35%. For larger problems, it is worthwhile to completely replace the rafter system.
Urgent repairs are required if there is a serious violation of the tightness of the coating: it may be necessary if part of the roof is torn off, water leaks during precipitation, peeling, rupture or swelling of the roofing material.
We provide the following warranty periods:
- soft roof: 5 years
- metal roofing: 3 years
- roll and bitumen coatings: 3 years
- polymer tiles and seam roofing: 6 years.
Any leak is a problem that requires careful and timely repair. Firstly, it is important to correctly determine the cause of the leak. Secondly, when self-repair there is a risk of damaging serviceable elements located nearby. If you are not a roofing specialist, we recommend calling a specialist who will not only fix the problem, but also provide a guarantee for his services.
In order to accurately determine the cause of the appearance of water, an examination will be carried out by a specialist. You can independently determine what is causing the appearance of moisture using the following signs:
- when a leak occurs in the roof, water begins to drip in the warm season after rain, and in the cold season during sunny weather and sudden warming.
- When condensation accumulates, moisture appears constantly and is practically independent of weather conditions.
Flat roofs are often used in the construction of modern high-rise buildings, administrative and industrial buildings, and in suburban construction. In the latter case, they are most popular when creating low-rise buildings or outbuildings.
Basic requirements for flat roofs
Increased roof strength is very important for regions with heavy snowfall. IN winter periods it will have to withstand significant stress as a result of the formation of a thick layer of ice and snow. This indicator is also very important in the case of creating a serviceable roof.
A flat roof must provide reliable protection from rain and melt water and have a sufficient slope so that precipitation does not linger on it.
The structure should not deteriorate under the influence of severe frosts and scorching rays of the sun, sudden temperature changes and heavy hail.
It should cope perfectly with the heat-insulating function.
All materials used in the construction of the roof must be fireproof.
Pros and cons of flat roofs
Pros:
- Flat structures have a much smaller area than pitched structures, which allows for significant savings on materials and during construction and installation work.
- A smaller area helps optimize costs.
- The construction of such roofs can be completed in a shorter time than with pitched roofs, since all the required materials can be placed in close proximity - literally at your feet.
- Due to the same feature, maintenance and carrying out are simplified. repair work: their implementation on a flat horizontal surface is greatly simplified.
- On flat roofs it is convenient to carry out installation and necessary maintenance work that requires the use of special equipment: solar panels, air conditioning systems, antennas, etc.
- By creating a flat structure, you can get additional meters usable area and use them as a recreation area, sports ground or arrange a flower bed or garden. Currently, it is possible to cover the roof with paving stones or paving slabs through the use of special technologies. Paved quality tiles roof combined with garden furniture, a green area, a gazebo will become ideal place for family holidays.
Minuses:
- during heavy snowfalls, a snow mass will accumulate on the surface, which, when melting begins, often leads to the formation of leaks;
- there is often a need to use gutters;
- in the cold season there is a risk of internal drainage freezing;
- the drainage system often becomes clogged;
- a mandatory requirement is mechanical cleaning of the surface from snow mass;
- periodic monitoring of the condition of the insulation is necessary to prevent its moisture;
- From time to time it is necessary to check the integrity of the coating.
Types of flat roofs
There are four main types of flat structures:
Operated roofs
Their peculiarity is the need to create a rigid base - otherwise it will not be possible to maintain the integrity of the waterproofing layer. The base is a screed based on concrete or corrugated sheeting, which is necessary to create a certain slope for water drainage. The thermal insulation material used in constructing the roof in use will be subject to significant static and dynamic loads and must have a sufficient level of compressive strength. If the insulation is not very rigid, a cement screed will be required on top.
Unused roofs
When installing this type, there is no need to create a rigid base in order to lay waterproofing material. No need for rigid insulation. For further service bridges or ladders are installed on the roof, the function of which is to evenly distribute loads over the roofing surface. The construction of unused flat roofs will cost much less, but they will not last as long as exploited ones.
Traditional roofs
The structure of traditional types of roofs involves the placement of a layer of waterproofing material above the thermal insulation material. The base for the roof is a reinforced concrete slab, and water is drained from the roofing surface by creating an inclined screed made of expanded clay concrete.
Inversion roofs
Inversion type roofs have practically solved the problem of leaks - the main drawback of flat structures. In them, the thermal insulation is located above the waterproofing carpet, and not under it. This technique helps protect the layer of waterproofing material from the destructive effects of solar ultraviolet radiation, sudden temperature fluctuations, the process of freezing and subsequent thawing.
Compared to other types of roofing, inversion roofing is more durable.
In addition, it is distinguished by increased functionality: you can lay a lawn on it and make tiled laying. Optimal angle The slope of such roofs is considered to be from 3 to 5 degrees.
Device Features
Basic subtleties of construction flat roofs are as follows:
- Vapor barrier is created using a bitumen-polymer membrane, fiberglass reinforced. Another option is to lay a vapor barrier film over the screed.
- Along the edges of the roof, a layer of vapor barrier material is placed vertically so that its height is greater than the height of the insulating layer, after which the seams are sealed.
- Insulation is laid over the vapor barrier (in the case of a traditional roof).
- A protective carpet is laid over the insulation, which is made of waterproofing materials with a bitumen base.
- If expanded clay is used as insulation, it must be made cement strainer. Waterproofing is laid on it in two layers.
- When installing lightweight structures that do not require significant loads, it is necessary to glue a waterproofing sheet along the entire roof perimeter.
Installation
A flat roof cannot be installed strictly horizontally - it must be observed minimum slope at least 5 degrees. This requirement is due to the need to ensure the drainage of rainwater and snow from the roofing surface. Another important point: it is necessary that the slope be created not only by the coating, but mainly due to the correct implementation of expanded clay or slag bedding. Even if the slope angle reaches 10 degrees, this will not interfere with the uniform laying of the heat-insulating material.
Lightweight flat roofs
When constructing such roofs, the work is divided into several stages.
As a result of the work done, a warm and fairly reliable flat-type roof is obtained: in cross-section, it resembles a multi-layer cake based on several components.
Hard roof installation
When creating floors of this type, expanded clay is best suited as a thermal insulation material. Minimum thickness its layer should be 10 cm. Above the laid expanded clay, it is necessary to make a cement-sand screed with a thickness of 40 to 50 mm. To ensure greater strength, a reinforcing mesh is placed in its middle layer. This measure is necessary to maintain the integrity of the coating while people are on it during repair, maintenance work, etc. In addition, these roofs are optimally suited as a base for constructing a swimming pool or recreation area.
The production of beams of such structures is most often carried out on the basis of a metal channel, since parts made of wood will not withstand significant loads.
Another requirement when installing roofs in use is the sufficient thickness and strength of the walls of the house.
Methods for constructing flat structures
There are several main ways to create flat roofs:
- By installing concrete floor slabs. Such work can be completed in a fairly short time, but special lifting equipment will be required. The use of this method involves the implementation of insulation. The material can be laid both inside and outside.
- Using metal channels or I-beams, on top of which it is necessary to lay boards: their thickness should be 25-40 mm. A layer of expanded clay is poured on top, then a concrete screed is created.
- The overlap is created using monolithic concreting. This requires high-strength formwork with thick supports. The supports are fastened together using jumpers. This type of floor also needs to be insulated.
- Using ceramic blocks large sizes: they are laid on top of metal beams. Such blocks replace wood flooring. The main advantage of this method is the use of ceramics, characterized by increased mechanical strength, resistant to moisture and having excellent sound and heat insulating properties. Large ceramic blocks do not require additional insulation: when using them, you can limit yourself to such a measure as creating a concrete screed.
CONCLUSIONS:
- Flat roofs are often used in the construction of modern multi-storey buildings, administrative and industrial buildings, and in suburban construction.
- Flat structures must have increased strength - especially if they fall out large quantity precipitation.
- Flat roofs have a much smaller area than pitched roofs, which allows for significant savings on materials and during construction and installation work.
- The main disadvantage of such roofs is that during heavy snowfalls, snow mass accumulates on the surface, often leading to the formation of leaks.
- Flat roofs can be used, non-used, traditional and inverted.
- Inversion type roofs have practically solved the problem of leaks - the main drawback of flat structures.
- A flat roof cannot be installed strictly horizontally - a minimum slope of at least 5 degrees must be observed to allow precipitation to drain off.
- The installation of flat roofs of lightweight construction is fundamentally different from the process of installing solid roofs.
- Flat roofs can be created in several ways.
In the video you can see how to organize drainage from a flat roof using the non-combustible Rockwool insulation system.
Many of us live in standard panel “nine-story buildings,” of which a great many have been built since the seventies. At the same time, a very small number of people are interested in what exactly the building in which they live is, limiting their interests only to their apartment. And I have always been interested in how the ecosystem called “home” works.
As a child, I climbed into basements, walked from basement to basement through the windows of the heating main, looked with a flashlight into black windows overgrown with cobwebs, opened closed doors attic hatches. I was interested in everything. The structures, smells and sounds of the roofs and basements indicated that the house was not just apartments, but a whole complex of complex systems.
And in general, this complements and changes ideas about what a city is and what a person is.
So, today’s walk is on the roof of a nine-story building; the same one that I first climbed in 1995.
02. The last floor in the entrance looks like this. It has an unusually high ceiling and these welded metal stairs leading to the rooftop exit.
03. To the left of the elevator (directly above the entrance to the apartments) there is such a hatch. I believe it has something to do with the maintenance of elevator equipment.
04. We go up the metal ladder. It is very inconvenient - you can immediately see that it is not designed for everyday use.
05. The direct exit to the roof is covered with a sheet metal shield, which is screwed to the base using welded bolts and nuts screwed onto them. Carefully unscrew it (and after visiting the roof, carefully screw it back in).
06. We go up another flight of stairs. It's even more uncomfortable than the previous one.
07. And here we are at the top. The first thing that catches your eye is the ventilation “fungus” of the garbage chute shaft, as well as the concrete decorative elements that cover the entrance windows.
08. Let's look back. In 1995, this exit to the roof was closed not with a metal shield, but with such a thick wooden door on hinges (I think of blue color), covered with tin. You can even see the remains of her box there.
09. The block itself, from which we came out onto the roof, looks like this. In addition to the exit itself, it also houses an elevator room with elevator equipment machines.
10. Elevator ventilation window. The blocks here are finished with the same crushed stone as the entire house.
11. This one concrete structure in the foreground is the exit of the apartment ventilation. Have you seen such grates in your bathroom and kitchen? They lead to a ventilation shaft that ends on the roof with something like this. TV network wires are passed through the reinforcing rings of the shaft cover.
12. The inside of the mine looks like this. Pretty clean, by the way. There is also a very specific smell here. It smells like some old oil, something like cutlets, some kind of buckwheat - the smell of dozens of kitchens. I remembered this smell very well during my very first visit to the roof. At that time, by the way, the mines were dirtier and some flakes flew from there along with the currents of warm air.
13. The entire roof and all surfaces on it are covered with this kind of roofing material for waterproofing. It is quite modern, grayish, and feels almost indestructible from temperature changes. When I was here for the first time, there was this old black roofing material lying here, swollen in places from the heat and cracked from the frost.
By the way, I don’t know what this block is in the center of the frame.
14. Water drain. They are located throughout the roof in such peculiar lowlands. Have you ever seen how, when it rains, water flows from such a bent pipe that looks out from the block under the first floor of a nine-story building? This pipe starts high on the roof with a drain like this.
14. But this metal tube is a cable channel brought out.
15. Now there is cable television in this house, but once there were large receiving antennas here, I remember them from my first visit to the roof.
Another cable channel, with parts of some kind of fastening equipment - maybe this is what the supporting straps of the antennas were attached to.
16. Some residents install satellite dishes on the roof, using the wall of such an elevation, formed due to the difference in height of different parts of the house. The elevation, by the way, is now covered with waterproofing, but I remember the time when it was just bare wall(it seems that it was even laid with brick for some reason), and a wooden ladder led from here to the higher part of the house.
17. View from the roof.
18. These wires on insulators are most likely the electrical network.
19. Some kind of metal structure at the exit from another entrance. I believe that these are the remains of a homemade antenna.
20. General view of the roof of the house. The artificial “lowland” of water drainage is clearly visible here.
21. Remains of some kind of cable. Most likely - part of the repair winch.
22. Isn’t it scary to walk on the roof? It's scary. The fence that seemed to me in childhood reliable protection, now it turned out to be very low and small.
23. And in some places these “railings” from the corner even end completely.
24. So let's look at the corner of the house and, perhaps, go down.
25. The most pleasant thing about walking on the rooftops is being back on the ground. Or even so - to end up on earth in the way that was originally planned :)
Flat roofs are made with load-bearing fully prefabricated or monolithic reinforced concrete structures. Such roofs are designed flat (with a slope of up to 5%) in three main options - attic, non-attic or exploitable.
Attic roof
The attic roof is the main type of roofing in residential buildings of mass construction.Roofless roof
Roofless in large public and industrial buildings. A roofless roof can be used in residential buildings with a height of no more than four floors, built in a temperate climate, as well as in limited areas of the roofs of multi-storey buildings - above elevator machine rooms, loggias, bay windows, over lobbies, vestibules protruding from the plane of the facades and low-rise extensions for non-residential purposes (trade, consumer services, etc.). In turn, the attic roof structure is sometimes used in multi-story buildings. public buildings, when their design and planning parameters coincide with the parameters of residential buildings, which allows the use of prefabricated buildings corresponding to them reinforced concrete products for roofs.Operable roof
The serviceable roof is installed over attic or non-attic coverings in buildings erected according to individual projects. It can be installed over the entire building or in individual areas of the roof.The type of drainage from a reinforced concrete roof is selected during design depending on the purpose of the object, its number of storeys and location in the building.
In residential buildings of medium and high rises, internal drainage is used, in low-rise buildings, it is allowed to use external organized drainage when placing buildings with a horizontal projection of the edge of 1.5 m or more from the red building line, and unorganized - in low-rise buildings located inside the block. In all cases of using unorganized drainage, provision is made for the installation of canopies over entrances to buildings and balconies.
For internal drainage in residential buildings, one water intake funnel is provided per planning section, but at least two per building.
For external organized drainage, placement and cross-section drainpipes prescribed the same as for pitched roofs.
Waterproofing of reinforced concrete roofs is designed depending on their type. For non-attic structures, as a rule, roll waterproofing coatings are used (with the exception of non-attic roofs of separate construction).
Waterproofing of attic and separate non-attic roofs is carried out in the following three ways: the first (traditional) - by installing a multi-layer carpet made of rolled waterproofing materials; the second - by painting with waterproofing mastics (organosilicon or others), which, together with the waterproof concrete of the roofing panel, provide protective functions coatings; third - the use of pre-tensioned roofing panels of high grade concrete for water resistance, providing roof waterproofing without painting with mastics.
According to the adopted method of waterproofing, the requirements for the characteristics of concrete roofing panels change (Table 20.2).
By air passage and release method exhaust ventilation through the design, attic roofs with a cold, warm and open attic are distinguished. For each of these structures, any of the above described waterproofing methods can be used when designing. Thus, the design of an attic reinforced concrete roof has six main design options (Fig. 20.13):
- A - with a cold attic and roll roofing;
- B - the same, with rollless;
- B - with a warm attic and roll roofing;
- G - the same, with rollless;
- D - with an open attic and roll roofing;
- E - the same, with rollless.
- F - separate ventilated (with roofing panel and attic floor) structure with roll roofing
- And - the same, with a roll-free roof
- K - combined three-layer panel structure
- L - combined multilayer construction manufacturing
Attic roof structures consist of roof panels ( roofing panels and trays), attic floors, supporting structures for trays and roofing panels, external frieze elements (Fig. 20.15). The height of the through passage in the attic space must be at least 1.6 m. Local reductions of up to 1.2 m outside the through passage are allowed.
Attic roofs with a cold and open attic (structure types A, B, D, E) contain an insulated attic floor, non-insulated thin-walled ribbed reinforced concrete roofing, tray and fascia panels, in which holes are provided for ventilation of the attic space. The area of ventilation openings on each longitudinal side of the facade is assigned in climatic regions I and II at 0.002 of the attic area, in regions III and IV - up to 0.02.
The dimensions of the supply and exhaust openings in the fascia panels of open attics are assumed to be significantly larger based on the results of calculating the ventilation of the attic space.
Ventilation blocks and shafts cross the roofs with a cold attic, removing the air mixture into open space over the roof.
Roof structures with a warm attic (types B and D) consist of insulated roofing, tray and fascia panels, an uninsulated attic floor and supporting structures of roofing and tray panels (Fig. 20.16). Since the warm attic serves as an air collection chamber for the building's exhaust ventilation system, ventilation blocks and shafts end in the attic space with caps 0.6 m high, without crossing the roof. Frieze panels are designed to be blank (without ventilation holes). These panels in some areas can be made translucent (for natural lighting of the attic), but not folding. In the central zone of the warm attic, a common exhaust shaft is installed (one per planning section) 4.5 m high from the upper plane of the attic floor.
Roof structures with an open attic (types D and E) are similar in composition to those with a cold attic, but the ventilation structures do not cross it, ending at a height of 0.6 m from the surface of the attic floor, as in roofs with a warm attic.
Peculiar architectural option structures of reinforced concrete attic roofs of multi-storey buildings; steel roofs with inclined frieze panels and vertical gable-shaped frieze panels, echoing traditional forms mansard roofs. This option can be used for both cold and warm attic roofs (Fig. 20.17).
The roof panels of roll-less roofs with a cold and open attic, as well as separate roofs without attics, are designed in the same way. These are thin-walled (slab thickness 40mm) ribbed reinforced concrete slabs. The butt edges of the panels and their junctions with vertical structures crossing the roof (elevator shafts, ventilation units, etc.) are equipped with ribs 300 mm high. The joints are protected by flashings (or overlapped) and sealed.
Drainage trough-shaped trays are made of waterproof concrete with a bottom thickness of 80 mm, a rib height of 350 mm, and a width of at least 900 mm.
Roof panels and roof trays with a warm attic are designed with two or three layers. Upper layer made of frost-resistant concrete with a thickness of at least 40 mm.
The design of a separate roofless roof (type I) contains the same structural elements, as an attic roof with a cold attic, but due to the fact that its air space has a low height (up to 0.6 m), the solution for supporting structures is simplified - they can serve as separate reinforced concrete bars.
Three-layer panels of combined roofs (type K) are manufactured in a single technological cycle or assembled at the factory from two thin-walled ribbed slabs and insulation between them.
Almost tripled in size regulatory requirements Due to the resistance to heat transfer of external enclosing structures, the use of the most industrial and economical design of a combined roof (as well as warm attics) made of single-layer lightweight concrete panels has ceased, since they have lost their economic profitability.
Traditional combined building-made roofs (type L) are erected by sequentially laying on the building over the ceiling (made of monolithic or precast reinforced concrete) the upper floor of a vapor barrier layer, fill along a slope, a heat-insulating layer, a leveling screed and a multi-layer rolled carpet. Design L is the most labor-intensive and has the worst performance characteristics. Its use should be limited as much as possible.
From Fig. 20.14 it is obvious that any of the attic roofs is a multi-layer structure, including a load-bearing reinforced concrete slab, vapor barrier, heat insulation and waterproofing (with a special prefabricated or monolithic base for it) layers. In this case, it is traditional to place a waterproofing layer on top, which leads (with a non-ventilated roof structure) to a decrease in the durability of the waterproofing carpet under the influence of solar radiation and the pressure of vaporous moisture accumulating under the carpet.
To increase the durability of roof waterproofing, a version of the inversion design has been developed and is being implemented - with the waterproofing layer located directly on the load-bearing slab under the thermal insulation layer (Fig. 20.18).
Changing the location of the thermal and waterproofing layers, in addition to increasing the durability of the roof, creates a number of additional economic and technological advantages. The inversion design is less massive, since there is no need to install a special foundation for the roof in the form of a cement-sand screed over insulation: the base for the waterproofing carpet is the load-bearing coating slab. Thanks to this arrangement of the carpet, the need to install a para-insulating layer is eliminated - the rolled carpet combines the functions of vapor and waterproofing.
Accordingly, the cost and labor costs are reduced, since the design and implementation of the interfaces of inversion roofs is simpler than that of traditional ones (Fig. 20.19). The fact that inversion roofs have so far received relatively limited use in domestic construction is due to the requirements for the physical and technical properties of insulation in such structures. It should have a low thermal conductivity coefficient of 1 3, a compressive strength of 0.25-0.5 MPa, a daily water absorption in % of volume of 0.1-0.2, be microporous and have a closed pore structure. The insulation must be hydrophobic, not allow swelling or shrinkage, and have the necessary mechanical strength. In practice, the possibility of expanding the introduction of inversion structures arises with the start of production of domestic extruded polystyrene foam boards "Penolex", and a corresponding reduction in the volume of exports of similar insulation materials.
Operable roof terraces are installed over warm and cold attic roofs, above technical attics, and sometimes above combined roofs (Fig. 20.20). Especially often last option used in buildings with terraced ledges in its volumetric form. The floor of terrace roofs is designed to be flat or with a slope of no more than 1.5%, and the roof surface below it is designed with a slope of at least 3%. The most durable materials are used for roofing (for example, waterproofing). The number of layers of rolled carpet is taken to be one more than with an unused roof. A layer of hot mastic antiseptic with herbicides is applied to the surface of the carpet. They protect the carpet from the germination of plant roots from seeds and spores blown onto the roof by the wind. When constructing a serviceable roof using an inversion combined structure, this role is played by a filtering synthetic canvas located under the ballast and drainage gravel layer. The roof-terrace floor is made of stone or concrete slabs, sometimes lined ceramic tiles. The floor slabs are laid loosely over a drainage layer of gravel.