Screed on a wooden floor is not the best solution for installing a new floor. However, despite this opinion, if all technologies are followed, it is actually feasible. In addition, there are designs wooden floors who are in good condition It’s easier to fill with a self-leveling floor than to redo the entire floor structure.
This article will be useful for those who are building their own Vacation home. Having made a self-leveling floor over a wooden one, it is easy to lay tiles in the bathroom or kitchen at home.
Also for owners country houses information about septic tanks from concrete rings. You can get information about septic tanks and place an order.
Wooden floor structures
Before you start talking about screeding a wooden floor, you need to understand the designs of wooden and plank floors.
It hardly makes sense to make a screed according to wooden floor, which is laid on joists and a 220 mm thick floor slab. The thickness of such a wooden floor is 70-77 mm and the best solution for such a floor would be to remove the wooden floor along with the joists and make a screed along concrete slab ceilings
Screeding a wooden floor makes sense if the floor joists are high brick pillars. The height of such pillars can reach 30-40 cm (or more) and it is not possible to replace them with a screed. You can see two photos of schemes for such floors below.
It is precisely floors of this design that can be discussed as a possible basis for a screed.
Features of screed on wooden floors
Before deciding to screed a wooden floor, pay attention to the following:
A screed on a wooden floor is an unconnected screed, that is, the layer of such a screed will not be connected to the bottom layer of the base and will be an isolated layer of the floor, not connected to anything. This leads to some features of screeds on wooden floors.
Firstly, the wooden base for the screed must be very strong and completely motionless. Depreciation, which is so characteristic of a wooden floor, should be completely eliminated. If the wooden floor possibly vibrates, the screed above it will crack, which is unacceptable.
Secondly, depending on the selected material for the screed, the thickness of the screed can be quite thick. For example, when using a cement-sand mixture for screed, the thickness of the screed should be from 10-12 cm. The weight of such a screed will significantly increase the load on the wooden floor. If we take into account that the wooden floor is laid on joists, and there is a step between the joists (the distance between the joists), then as the load on the wooden floor increases, the distance between the joists must be reduced. IN large rooms the distance between the logs can reach 85 cm. Therefore, having decided to make a cement-sand screed in big room, you have to disassemble the floor, reduce the step between the joists by installing new joists and restore the wooden floor again.
It’s a lot of work, and perhaps you should think a hundred times before making a cement-sand screed on a wooden floor in a large room.
In order not to disassemble the floor and not reduce the distance between the joists, use not a cement-sand mixture, but, for example, anhydrite floor levelers. The thickness of such a screed is from 30 mm, the leveler does not require reinforcement and can be used for unbound screeds.
Third, A cement-sand screed on a wooden floor is made, always with a reinforcing mesh. This is done, again, to increase the strength of the screed. Moreover, fiberglass in the screed will not save you from using reinforcing mesh. That is, for a semi-dry screed, you will also have to make a reinforcing mesh with cells of 100×100 mm.
Conclusion. The use of cement-sand screed for large rooms with wooden floors is not justified by labor-intensive work. However. If the circumstances and conditions are such that it is impossible to avoid screeding a wooden floor, then to install the screed it is better to use a leveler suitable for independent screeding rather than using a cement-sand mixture. And in general, I would not consider a cement-sand screed as a priority for screeding on a wooden floor, although the use of a high-quality leveler will significantly increase the cost of the screed material.
Material for screeding on wooden floors
To make a screed on a wooden floor you will need the following material:
class="eliadunit">
- Polyethylene film with a thickness of 200 microns, for waterproofing the screed layer from wood and walls;
- Mixture for screed. Read about choosing a mixture a little higher. If you choose a cement-sand mixture, then prepare a reinforcing mesh, preferably with a stainless steel coating. The mesh should not be in rolls. Why not in rolls?
You have to fix the reinforcing mesh on a wooden base, but you must not disturb the waterproofing, that is, do not tear the film. Think about how you will attach the mesh. At the same time, think about how you will attach the beacons for the DSP screed, because there is nothing to attach the beacons to, the base for attaching the beacons is polyethylene.
Why am I making these notes? In my opinion, it is better not to install a cement-sand screed on a wooden base in large rooms. The amount of work and problems will completely overshadow the result. Replace DSP with “Rovnitel” for isolated bases (unbound screed). For example, an anhydrite floor leveler.
Wood screed technology
The wooden floor must be strong, immovable, dry and not rotten. The same applies not only to the floor boards, but also to the joists and pillars on which it is laid. Rotten boards need to be replaced.
Important! Do not screed on a newly laid wooden floor; it may become deformed. The age of the wooden floor for screed must be more than one year when the floor is used in the range of home temperatures. Although I can’t imagine who needs to screed a new wooden floor.
The heads of the nails with which the boards are nailed need to be recessed a few millimeters so that they do not tear the layer of waterproofing film that needs to be laid on top of the boards.
If your apartment is on the ground floor and there is a basement or ground below you, then the seams between the boards need to be filled with epoxy putty. Epoxy putty is chosen because it does not allow moisture to pass through. The seams are sealed so that evaporation does not form between the film laid under the screed and the boards.
If the joints between the wall and the floor are wide, then seal them construction foam, and on top with epoxy putty and liquid waterproofing.
After the putty has dried, polyethylene 200 microns thick is spread on the wooden base. Polyethylene is spread with an overlap of 10-15 cm on the walls. Two adjacent pieces of polyethylene are laid with an overlap of 20-25 cm. Seal the joint between the pieces of polyethylene with non-wetting mounting tape. Tape the overlaps to the wall with tape.
The polyethylene should lie flat, without folds. Under the polyethylene there should be a clean wooden base free of debris.
Preparation of the solution
Let me remind you that we make a screed from a mixture of leveling agent. We make the screed solution according to the instructions on the package. The leveler mixture is added to the water, not the other way around. Stir the mixture until it becomes thick sour cream. mechanically, mixer at low speed.
How to check the thickness of the mixture
To check that the consistency of the mixture is correct, find a container with a diameter of 70 mm so that it can hold 1 liter of solution. From this cylinder, pour 1 liter of solution onto a 50x50 cm plexiglass plate. The diameter of the spread solution should be 34-38 cm. This means that the density of the solution is correct. The density of the solution must be checked constantly.
Set the screed level
The unbound screed with leveler must be more than 30 mm. For a wooden floor, choose 50 – 60 mm. It is better to measure the level of the screed with a laser level. If the room is very small, a building level is sufficient. Using the laser level, draw a screed line along the wall and place benchmark beacons (levels on legs) along the floor surface.
Filling the screed
The finished leveling mixture is poured continuously over the entire surface of the floor from the far corner to the exit. Helpers will be needed for successful pouring. One dilutes the mixture, the second continuously pours the solution, the third levels the solution according to the level of the beacons and marks, using a special metal rod with oscillatory movements (raising and lowering the rod) along and across the cast surface.
Caring for a poured screed
In a room with a poured screed there should be no drafts and low temperatures. If you did use a solution from CPS, then cover the screed with polyethylene. Anhydrite self-leveling floor must be protected from excessive insolation (direct rays of the sun) for 2 days, too high temperature, drafts and water. After two days the room needs to be ventilated.
Some conclusions of the article
- Before screeding, evaluate the structure of your wooden floor;
- Cement-sand screed is very heavy and will put a lot of stress on the wooden floor, so you may have to reinforce the wooden floor;
- If possible, replace the DSP with a high-quality leveler for an independent screed;
- DSP screed on a wooden floor is cost-effective only for small rooms, kitchens, and bathrooms;
- Think a hundred times before using a screed on a wooden floor in houses with wooden floors, remember the load.
- And one last thing. If you plan to use tiles as finishing, replace the screed on the wooden floor, if possible in level, by laying cement bonded bonded boards (CBB).
Wooden floors are rarely leveled with concrete. Many experienced builders believe that the hoisting of heavy monolithic design on a wood floor makes no sense. Moreover, the concrete layer does not coexist very “friendly” with the wooden base, not only during hardening, but also during operation. In this regard, it is more advisable to use dry leveling schemes. But in cases where it is necessary, for example, to lay in a washing room tiles, we have to look for a way out of the situation.
Let’s immediately say that concrete screed on a wooden floor is a completely feasible task, but here, as in any other matter, there are specific issues.
Plank floor - photo
Wood is a special material that has not only a number of technological advantages, but also one significant drawback. It is not static, so even after completion installation work“behaves” according to his own laws, peculiar only to him. Changes in temperature and humidity cause lumber to shrink, increase/decrease in volume, stretch or contract. By the way, it is for this reason that after the construction of the log house fine finishing is carried out somewhere in 2 years.
But even after a two-year period of shrinkage, wooden structures are still moving, albeit not as intensely. For example, a wooden floor with underfloor heating moves every time the heating system is turned on.
Video - Concrete floors in a wooden house
Unlike wood, a monolithic concrete base only slightly changes its geometric parameters when hydrated, and after complete hardening it hardly moves at all.
And if this base were tightly connected to the unstable wooden surface, then the slightest movements of the latter would lead to the formation of cracks on the surface of the concrete.
One of the reasons for the appearance of cracks is non-compliance with the technology of pouring concrete on a wooden base.
But the alignment technology described here is intended to ensure that both elements cannot harm each other, and its (technology) distinguishing feature lies in the fact that during pouring the base is not connected to the walls.
Diagram - an example of arranging a screed on a wooden floor
Design features of plank floors
It is hardly advisable to pour a screed on a floor equipped with joists and a floor slab. Such floors often have a thickness of approximately 7-7.8 cm, and the only correct solution in this case can only be to dismantle all wooden elements followed by pouring over the floor slab. It’s another matter if the logs are high and located on brick pillars. Such pillars have a height of over 0.3-0.4 m, so it is impossible to replace them with a concrete screed. Schemes of such floors are presented in the images below.
1 – base; 2 – waterproofing made of two layers of roofing material; 3 – bottom harness; 4 – top trim; 5 - external cladding tongue and groove boards; b – plate made of non-ferrous metal with holes; 7- outer wall from boards; 8 – plaster; 9 – plinth; 10 – plank floor; 11 – logs; 12 – brick column; 13 – antiseptic wooden lining; 14 – underground 
1 – compacted sand; 2 – concrete preparation; 3 – waterproofing from roll materials; 4 – brick pillar; 5 – wooden antiseptic lining; c – cladding made of antiseptic boards; 7 – intermediate plank flooring: 8 – thermal insulation; 9 - air gap; 10 – floor; 11 – load-bearing beam
It is precisely such structures that are often filled with screed.
Pouring technology
The essence of pouring a concrete screed plank floor consists of creating a gap between the monolithic surface and unstable wooden elements. For this purpose, the leveling layer is cut off from the walls using a damper tape, and from the plank base - with polyethylene.
This creates a floating floor without connections to any surface. As a result, all lumber elements continue to move in one direction or another, and the screed, which simply lies on top, does not become covered with cracks from permanent changes in the position of the boardwalk.
The technical parameters of the concrete screed, as well as the basic requirements, are found in SNiP 2.03.13-88 and 3.04.01-87.
SNiP 2.03.13-88. Floors. File for download
SNiP 3.04.01-87. Insulating and finishing coatings. File for download
On the feasibility of using polyethylene
Direct contact with plastic film is known to have a negative effect on wood and leads to the growth of fungus and mold.
That is why instead of film in wooden structures roofing felt, bitumen-based mastic, glassine or roll waterproofing with bitumen impregnation. But cement strainer does not stick to polyethylene film at all, which is why:
- both plates will be able to move freely along the insulating boundary;
- the screed will not draw moisture from the wood, leading to cracks;
- When moving, the screed will not pull the film, stretch it or tear it.
Important information! Before starting work, care should be taken to minimize Negative consequences contact of lumber with polyethylene. To do this, all wooden elements need to be processed antiseptic and the Aquastop primer mixture, which has moisture-repellent properties.
The filling procedure itself consists of several stages, let’s get acquainted with them.
Prices for reinforced polyethylene film
reinforced polyethylene film
Stage one. Calculations
There is one standard scheme calculations: for every 15 kg/m² of dry mixture there is a thickness of 1 cm. Even if the required amount of materials is known, you still need to buy them with a 10% margin.
Table. Dry cement mixtures - cost
| Name | Manufacturer | Package | Price |
|---|---|---|---|
| "VOS Mixtures" | Bag, 50 kg | 95 rub. | |
| UMIX | Bag, 50 kg | 100 rub. | |
| "Stone Flower" | Bag, 25 kg | 75 rub. | |
| "Polymin" | Bag, 25 kg | 118 rub. | |
| Kreisel | Bag, 25 kg | 132 rub. | |
| Manufacturer: Ceresit | Bag, 25 kg | 160 rub. |
Stage two. Preparing the base
Having understood the technology and calculated the required amount of mixture, you can proceed directly to work. Traditionally, you should start by preparing the base.
Step 1. First, the boardwalk is dismantled and a thorough inspection of all elements is carried out. Lags are checked. If any of them are unsuitable for further use, they must be replaced.
Step 2. If the logs are installed in increments of more than 40 cm, then auxiliary bars are installed between them.
Step 3. The boards, if they are still usable, are nailed back together. If slightly damaged floorboards are found, they should be turned over.
The heads of the nails are recessed by 2-3 mm, otherwise the plastic film laid on top may tear.
Step 4. The baseboards are removed and thin boards are installed instead (the latter should cover the cracks in the walls). Do not forget that these boards are installed for a certain time, and after pouring the screeds will be dismantled. This will provide ventilation wooden base, will prevent it from rotting.
Important information! You also need to seal all the cracks. If they are small, you can fill them with sealant, but large cracks are better sealed with foam.
Instead of sealant, you can use parquet putty made from wood dust, or a homemade putty mixture. To prepare the latter, you need to mix any sawdust with oil paint in a ratio of 4:1.
Stage three. Padding
When the sealant or putty is completely dry, thoroughly vacuum the substrate to remove dust and debris. Sanding can be done if desired, although this is not necessary.
Next, a moisture-resistant primer is applied in two or three layers: it will prevent the appearance of air bubbles and the absorption of liquid from the cement mortar by the surface. The primer will also serve as additional protection for the wood from mold and mildew.
Prices for primer for concrete floors
primer for concrete floor
Stage four. Marking
Using ordinary or laser level A zero level is marked along the perimeter of the walls. The latter can be at an arbitrary height, but on average it is 35-70 cm from the surface of the base. It is necessary to mark several points of the zero horizontal on each of the walls.
Equal distances are laid down from these points, and the thickness of the screed itself must be taken into account.
Important information! The standard thickness of a concrete floating floor is about 5 cm. Moreover, every centimeter of such a floor will create a load on plank base 100-110 kg each square meter. It is for this reason that it is advisable to strengthen the logs, although if possible it is generally better to install metal channels instead of them.
Stage five. Waterproofing
Further actions involve insulating the wooden structural elements, and the result should be a kind of pallet that does not allow moisture to pass through.
Step 1. A damper tape with a thickness of 10-20 mm and a width slightly exceeding the thickness of the screed is attached to the walls along the entire perimeter. This tape will provide not only extinction sound vibrations, but also the possibility of lengthening/expanding the floating slab. Scotch tape is used for fastening.
Important information! At the end finishing floor, excess tape protruding on the surface will be cut off, and the resulting gap will be covered with a plinth.
Important information! There should be no folds or damage to the waterproofing layer. Subsequent steps must be performed with extreme caution so as not to tear or puncture the film. If this cannot be avoided, the holes must be immediately covered with polyethylene patches.
Step 3. Ideally, the waterproofing layer should have no joints at all. If there are joints, then they are all firmly taped with tape. Further work The leveling layer will largely depend on the tightness of the waterproofing.
Prices for edge tape
edge tape
Stage six. Reinforcement
If the concrete layer is thick enough, it must be reinforced. There are several methods of reinforcement; only the most common ones are discussed below.
Method number 1. Reinforcing mesh
A very common option, which, however, is not particularly suitable in this case. The fact is that the previous layer is polyethylene, which can be damaged by the mesh. It will be quite difficult to move around the fittings without compromising the integrity of the insulation. In addition, the film, as noted above, must be in direct contact with the concrete, so the mesh must be located in the body of the screed.
For this reason, concrete is poured in two layers:
- the first layer is poured - without beacons;
- the grid is laid, beacons are installed;
- the second layer is poured.
It would seem nothing complicated, but the concrete layer will take a long time to dry - the break between layers can be up to 1 month. Therefore, it is better to resort to the second method.
Method number 2. Fiber fiber
The next reinforcement method is to add fiberglass directly to the concrete mixture still at the preparation stage. The polymer fibers that make up this material are arranged randomly, resulting in maximum bond strength in all directions.
Moreover, total weight screeds will be noticeably reduced due to the abandonment of metal mesh. Further actions are focused on using this particular method.
Fiber fiber prices
fiber fiber
Stage seven. Installation of leveling
Lighthouses need to be built especially carefully; there can be no talk of any screws or nails. The foundations for future “beds” are made from the same mortar that will be used for the screed. “Beds” are formed along the entire length of each of the lighthouses.
Important information! The distance between the “beds” must be 10-15 cm shorter than the length of the rule (often about 120 cm). The distance between the wall surfaces and the outer “beds” should be 25-30 cm.
The metal profile is laid on the tops of the “beds” and heated in the solution so that the previously noted height (level of the leveling layer) is reached. The installation of beacons must be completed a maximum of an hour after mixing the solution, otherwise it will set.
Stage eight. Mixing the solution
The mixture for concrete screed can be purchased already in finished form or do it yourself. Factory-made dry mixes are sold in bags of 25 kg and 50 kg and diluted with water (6.5 liters per bag or 13 liters, respectively). If necessary, the amount of water can be increased, but not more than 0.5 liters.
All components are mixed with an electric drill with a mixer attachment, ready mixture should be used for a maximum of 15 minutes.
For self-cooking solution, you need to mix cement (at least “four hundredth”) and sifted sand (preferably river sand) in a ratio of 1:3. An electric drill is also used for kneading, but the whole procedure is performed in 2 stages. The prepared solution should be used no later than 1.5 hours after mixing.
Important information! The strength and water resistance of the solution can be increased by adding special plasticizers (the proportions are indicated on the packaging). Although there is a cheaper alternative to plasticizer - regular washing powder(a handful for every 100 liters of water).
Prices for cement-sand mixture
cement-sand mixture
Stage nine. Fill
The filling procedure is carried out traditionally, i.e. continuously. You should start from the far corner relative to the front door. The surface is leveled using a rule.
24 hours after pouring the screed, the beacons are removed, and the remaining voids are treated with a primer, filled with the same solution and leveled using a trowel.
Video - Screed on a wooden floor
Further care of the screed
The care requirements are the same for both ready-made dry screed and homemade cement-sand mortar. The next day after pouring, the screed is moistened, and the procedure is repeated daily for one week. For the first four days, the concrete should be covered with plastic film so that moisture evaporates evenly from the screed.
This completes the procedure for pouring screed onto a wooden floor.
When renovating a house or apartment, a master may encounter a problem with a wooden floor. Over time, such coatings become creaky and lose their evenness. Various types of damage may also occur. To shorten the duration repair work, it is best to install new flooring without removing the old wooden floor.
To level the base, a screed on a wooden floor laid under the tiles is perfect. It is important to consider this option, since installing tiles is the most difficult task for a wooden floor. The material is characterized by high density and has a strong impact on the underlying structures. If you understand how to make a screed for tiles, there will be no problems with other coatings.
How to make a screed
There are two options for performing the work:
- standard concrete pouring;
- using the dry method.
The second option is more suitable for wooden floors because it has the following advantages:
- small weight;
- ease of manufacture;
- convenience of laying communications;
- ability to correct errors;
- no wet processes;
- there is no need to wait for drying, which is required by a cement screed.
But there are also disadvantages for use in the home:
- making a dry screed requires a greater thickness than the concrete one is made (the height of the room is reduced);
- due to the increased thickness, the consumption of materials is higher than when creating a traditional base.
Depending on the conditions, requirements and wishes, you can choose between two options when laying material under the tiles.
Work production technology
Screed under tiles on wooden floors should be done strictly in the prescribed manner. When renovating a house, you first need to inspect the ceiling and floor structures. Reveal weak spots, make sure there is no serious damage. If traces of rot, mold, fungus and other microorganisms are found, it is better to selectively replace the elements of the wooden floor.
Scheme for preparing a wooden floor before laying tiles, part 1 
Scheme for preparing a wooden floor before laying tiles, part 2 Using a screed, you can eliminate unevenness and strengthen the surface before attaching the floor covering, but you will not be able to get rid of serious defects. The base for the tiles must be level and strong, since it will have to withstand heavy loads. To prevent problems during operation, it is better to timely replace and remove old boards in the house.
After inspecting the old floor, you can begin the main task. Make a classic fill wet screed It is recommended in the following order:
- If there was previously a cement screed on the floor, it can be removed by grinding or milling.
- Checking the reliability of the fastenings of the flooring boards to the joists. If they are not securely fastened, squeaking will occur during operation. To prevent this, all elements of the old floor must be securely attached to each other.
- Next comes cleaning the surface from old contaminants. You will need to remove grease, traces of glue, old paint and varnish, various impregnations, dirt and dust.
- If necessary, you should sand the surface of the old floor with a special machine. In this way it is removed upper layer, the base under the tiles becomes smoother.
- If there are unevennesses on the floor with a height difference of more than 1 cm, you need to do preliminary leveling for the tiles. To perform the work, you can use various leveling mixtures based on a cement binder. The surface of the boards is covered with the composition; cracks can be repaired using putty. Water-soluble putty compounds cannot be used.
- Instead of baseboards, slats are installed around the perimeter of the walls, which will cover the distance between the old floor and the wall. Thin slats are installed followed by puttying. This strip is removed after completion of the work. With its help, a gap is provided that will allow air to enter the space under the floor. For wooden covering this is extremely important, because if ventilation measures are not taken, the wood will rot and cause problems during operation.
- The leveled surface must be primed in accordance with the technology of this process. For priming, buy a ready-made mixture. A layer of this material will not only increase adhesion, but also improve the spreadability of the mixture for pouring the subfloor over the surface when performing repair work. When processing, the floor must be dry, the work is performed in two times.
- Having finished with the previous stage, you need to lay a reinforcing mesh under the tiles. The diameter of the elements is assumed to be 3-4 mm. Cell dimensions 50 by 50 mm. This stage can be neglected, but it ensures greater reliability of the foundation and the ability to withstand higher loads.
- When preparing the solution, the proportions must be observed. It is better not to make it yourself, but to buy a ready-made dry mixture, the preparation of which requires only water. This will avoid mistakes when choosing the proportions of components and reduce the complexity of the screed pouring process.
- The mixture must be applied in one go. If you carry out work in several stages, the layer will not work as a single whole, cracks, tears and unevenness will appear. For application, use notched spatulas. Control the thickness of the application using beacon guides or marks on the wall surface.
- After completing the laying of the mortar, it is necessary to allow the concrete to cure. This process when normal conditions takes several hours. After this time, you can carefully walk on the floor, but it will be ready for full use no earlier than in a couple of weeks (in the summer, the time period increases for the winter season).
- Take out the slats installed around the perimeter of the walls instead of baseboards. After this, if necessary, grinding can be done (no earlier than 6 hours after pouring).
Our project expert, Natalya Kaplunova, answers
Photo: www.topdom.ru
Screed on a wooden floor is different from pouring on another base. A wooden base has completely different characteristics than a stone base, which must be taken into account. Since a wooden floor is prone to deformation, the concrete screed should not cling to the wood so firmly as to interfere with its natural movement, otherwise cracks cannot be avoided. And the wood itself “breathes” and can affect concrete, so insulation between these materials is necessary. This technology is called unbonded screed.
Preparatory work includes replacing damaged floor boards. Some boards can be flipped over to give a smoother, cleaner surface. Next, the surface is thoroughly cleaned, including removing loose paint. The heads of nails or screws are recessed deeper so as not to damage the insulation. The cracks are sealed with epoxy putty; in problem areas you can use polyurethane foam. It is advisable to treat the joints of the boards with a sealant that has silicone or acrylic base. The prepared surface should be coated with a layer of moisture-resistant primer (as an option - water-resistant paint).
Before pouring concrete, polyethylene film should be stretched over the wooden floor without wrinkles so that the concrete and the base do not touch. Joints and possible suspicious places should be reinforced with tape to ensure truly airtight insulation. Attach the edges of the film with a stapler to the walls. The allowance above the edge of the planned screed is taken up to 5 cm.
Next, “beacons” (slats made of metal or wood) are placed along which the solution will be poured. The height of the screed should be at least 5 cm. It would be good if additional reinforcing mesh was laid. It is worth adding plasticizers to the solution, which will both accelerate the development of maximum strength and increase water resistance. If a self-leveling mixture is used, then beacons can serve stretched threads, Although this method will be more expensive.
The room must be filled completely at one time; filling in parts is not allowed. When laying, you should pierce the surface with a metal rod or a special needle roller so that the coating does not have air bubbles that impair its strength. After pouring the prepared solution, the surface is perfectly leveled using a rule or at least a spatula.
Strength gains only over time, so proper drying must be ensured. While the solution is drying, you should periodically moisten the surface with water (the first few days). Only after the solution has dried can the slats be removed and primed, sealed and rubbed over the voids cement mixture. Next, the surface is wetted again and covered with polyethylene for two weeks. After this, the polyethylene allowances can be cut off.
Before deciding to pour a concrete screed, you need to make sure that the foundation can withstand a significant increase in load. You cannot apply a screed to a fresh wooden floor: the new wooden floor may deform too much, which will damage the top covering.
And finally, we suggest you look videos about leveling a wooden floor.
To reduce the renovation time in a house or apartment, it is better to lay a new floor covering on top of the old one. It should be borne in mind that old wooden floors are often uneven, and the surface must be leveled before laying the tiles. To do this, you should arrange a screed. It is made using two technologies: standard concrete pouring and the dry method. Let's take a closer look at them.
Dry base
For several reasons, this technology is most preferable when working with wooden floors:
- ease of manufacture;
- low weight of the structure;
- good sound insulation;
- ease of laying communications;
- the opportunity to correct mistakes;
- no wet processes.
On a note! This last point means that when using the dry method, you do not have to wait for the floor to dry (unlike the cement base process).
This method also has several disadvantages. Such a screed on a wooden floor should be thicker than concrete (which reduces the height of the room). The consumption of materials will be higher than when creating a classic base for flooring. Dry base should not be done in rooms with high humidity, since the backfill absorbs any vapors.
The following can be used as backfill:
- expanded clay;
- vermiculite;
- perlite;
- compevit.
Expanded clay is the most common filler. It must be clean (no dust or sand), otherwise the floor will begin to creak very quickly. The appropriate grain size is no more than 0.5 cm, they should be approximately the same size (otherwise smaller granules will fall between the larger ones, which may cause the floor covering to sag). Minimum thickness expanded clay layer - 3-4 cm.
On a note! If the material is not defective, the expanded clay granule in the section should be porous. To ensure their quality, expanded clay granules should be purchased in bulk and not in closed bags.
Work production technology
When starting work, assess the condition of the ceilings and existing flooring. Weak and damaged areas, rotten and moldy elements must be replaced. To do this, it is worth using the most dried parts to avoid rotting of the wood in the future.
If the boards sag, this can be corrected by laying additional joists. The heads of the nails that stick out above the surface must be buried with a hammer. Large irregularities can be cut off with a scraper or a plane.
How to make a screed?
The technology looks like this:
- Stretch a layer of insulation (film) over the entire area of the room; it must have a slight overlap on the walls (above the level of the future coating);
- Take the edge tape and create a damper seam around the perimeter of the room;
- Fill the space with insulating and leveling dry material and distribute it evenly to the designed thickness;
- Place on top of the backfill gypsum fiber sheet(this should be done without creating cross-shaped joints);
- Next, lay the second layer of GVLV so that the seams of the first layer do not overlap the seams of the top one.
Important! The quality of the dry base is highly dependent on how the first fiber sheet was laid. Avoid the slightest distortion and burying in the backfill. It's better if you do this with the help of an assistant.
Classic floor screed
If you decide to go the traditional route - pour a concrete base for the tiles, you will need to carry out the same preparation as when working with dry technology. Check the floors and the condition of the boards, eliminate weak elements and unevenness, and fill the cracks with epoxy putty.
On a note! Large cavities can be blown out with self-expanding foam and covered with moisture-resistant acrylic sealant. Ideally, after the putty and sealant has hardened, the entire floor area should be treated with a waterproofing compound.
Preparing for pouring
A cement screed on a wooden floor needs the same preparatory activities, like dry:
- Spread plastic film over the entire surface (with an overlap of at least 20 cm on the walls; you can secure it with edge tape or tape), do not allow wrinkles or bubbles to appear;
- Install beacons. To do this, lay piles of thick cement mortar on the film and attach metal perforated slats to them;
- Level the beacons using a level (add or remove mortar from the cement slides);
- Make reinforcement. There are two ways to do this. The simplest is to add fiberglass or steel fiber to the solution (the strength of such a layer will increase as the cement hardens). Another method involves installing a continuous reinforcing mesh, which is laid on a layer of polyethylene under the supports of the beacon battens.
Important! In some cases, the thickness of the cement-sand layer can exceed 10 cm, which means that the joists and floors will be subject to high loads. Before you build a cushion under the tiles, consider additionally strengthening the floor: residential buildings The lag laying step can reach 90 cm; it makes sense to reduce this distance to 40 cm.
Pouring and drying
The concrete base is poured onto wood flooring according to the following algorithm:
- knead cement mortar(M400 cement and sand in a ratio of 1:3 or 1:4), or use a ready-made mixture (the main thing is to ensure sufficient fluidity of the composition);
- fill, evenly distributing the solution between the beacons and preventing the appearance of air voids;
- take a rule and level the surface along the beacons;
- leave the filling to dry for 48 hours;
- remove the beacon slats and fill the voids left behind with fresh solution;
- Perform final leveling of the surface using wet half-tracks.
Filling must be done in one step. If you divide this process into stages, the screed will turn out to be non-uniform, which can lead to the rapid appearance of cracks and irregularities.
Apply the solution to the surface using a notched trowel; control the thickness of the layer using guides or marks on the walls.
On a note! Concrete must gain strength before final curing. Therefore, you should slow down the drying process. To do this, moisten the surface and cover it with polyethylene. The solution will gain brand strength within 3-4 weeks. During this period of time, it must be moistened at least once every two to three days.
Within a couple of weeks after pouring concrete base You can walk carefully, but it’s better not to rush when laying the tiles. Keep in mind that in the cold season the solution will dry more slowly. When it has completely hardened, cut off the film protruding along the edges and complete the final leveling of the surface using grinder. After this, you can lay a new floor covering.
Summary
Even if you plan to use a different floor covering, it is important to screed the wooden floor under the tiles. It is a high-density material and has a strong impact on the structures below. Having dealt with tiles, you can easily cope with other materials.
Remember that the screed is designed to remove relatively minor irregularities and strengthen the surface before installing the tiles. To get rid of serious defects, you will have to replace the old boards or completely dismantle the old covering. Neither the concrete nor the dry base should move during operation. For a more complete understanding of the technology of work, watch the video about arranging a screed.
Video: screeding a wooden floor