Do-it-yourself subfloor in a wooden house: installation of subfloors along joists and installation methods. Subfloor in a wooden house How to make a subfloor

When building a new house or renovating an old one, it is very important to properly make the floor for laying the flooring. If you are going to make a subfloor in a wooden house with your own hands, then you should know how to construct it and the manufacturing technology to choose the best option. To choose the right subfloor option for a wooden house, you need to take into account the features of the floor covering, as well as the need for hydro- and thermal insulation.

Floor design

Regardless of the choice of method for constructing the subfloor, the following layers must be provided in the structural cake:

• Underlying layer. This is the bottom part of the floor pie. The layer is needed to evenly distribute the loads from the elements laid above. Typically, this structure is made of floor slabs, beams (joists), rammed soil or concrete preparation.
• Intermediate layer needed to connect the lower and upper elements of the pie into one whole (it is not available in all designs).
• Insulation layer performs the functions of heat, hydro or sound insulation of the floor. The choice of materials for this layer depends on the design features, the purpose of the room and the type of floor covering.
• Rough leveling layer. The purpose of this part of the pie is to level out the unevenness of the previous layer. Sometimes at this stage the required slope of the floor surface is provided. The arrangement of this layer can be done using a dry backfill of sand or gravel or by installing a concrete screed.
• Final leveling layer. It is not always needed. Laying the finishing layer is required when finishing the floor with laminated boards, carpet or linoleum. Finishing leveling does not need to be done under ceramic tiles.

Two flooring options are suitable for a wooden house:

• arrangement of floors along logs;
• You can make a dry screed or pour a wet screed.

In turn, the arrangement of floors along logs in a private wooden house can be carried out on beams or a concrete base. By the way, such floors can be installed in a brick house or a building made of foam blocks.

Subfloor on joists

Preliminary stage of floor installation using joists

If you decide to make a subfloor using joists with your own hands, keep in mind that the joists are a supporting element for laying subflooring made of plywood, boards, or OSB. In turn, depending on the design of a private structure, logs can be laid on pillars, beams or a mortgage element. They can be used not only in a private wooden house, but also in a house made of foam blocks.

If the room is large, then attaching the edges of the logs to the beams will not provide adequate strength to the base. In this case, it is necessary to use intermediate posts. The pitch of the support columns depends on the cross-section of the logs. Usually the step is taken to be 0.8-1 m. The material of the columns is brick or concrete. Even in a house made of foam blocks, it is better to make columns from durable materials.

The column is installed on a shallow concrete foundation. The foundation is installed over a layer of compacted sand and crushed stone. The brick column is insulated from the joists and the foundation with rolled insulating material, for example, roofing felt.

Technology for constructing a subfloor using joists

The subfloor in a wooden house with joists is done in the following order:

1. Before installing the logs, it is necessary to stretch the fishing line above the surface and mark the places where the beams are attached. This will allow the elements to be placed on the same level, which will facilitate further work on the floor installation.
2. If the installation of logs in a private wooden house will be carried out on a base made of concrete, foam blocks or bricks, then they must be protected with a layer of waterproofing. This way the wooden elements will not absorb moisture from the base. Thick polyethylene film can be used as insulation. In addition, logs must be treated with fire retardants and antiseptics.
3. The installation step of the joists depends on the load on the floor. For a living room, the optimal log pitch is 45 cm. The logs are screwed to the base using self-tapping screws and dowels pre-installed in the drilled holes.
4. All wooden structural elements must be treated with impregnations that protect the wood from rotting and burning.
5. If the floor of the first floor is being installed, the room must be protected from moisture and insulated. To do this, bars are nailed to the bottom of the side surfaces of the logs on both sides. You can use timber with a cross section of 50x50 mm.
6. Next, you need to make a backing of plywood or boards for laying in the gaps between the insulation joists. To do this, sheets of plywood are cut according to the width of the gap between the joists and laid on top of the bars. Plywood is nailed to the beams. As a result, you will get a structure made of wood, like the letter “W”.
7. Before laying the thermal insulation material, it is necessary to make a waterproofing layer. To do this, the insulating material is laid on the joists so that it sag into the gaps between them. For these purposes, you can take membrane waterproofing or polyethylene film.
8. Now the insulation is laid in the gaps between the joists directly on top of the insulating material. Thermal insulation can be done using mineral or basalt wool. We attach the film to the joists with a stapler.
9. To properly make the floor, you need to remember about the vapor barrier. To do this, the film is laid over the logs and thermal insulation material. Be sure to overlap adjacent sheets by 15 cm. The joints are taped.
10. Now you can lay the rough flooring. It can be made from plywood, chipboard, boards or OSB.
11. Depending on the choice of floor covering, the finished floor can be laid next, or finishing leveling can be carried out for laying tiles, laminate or linoleum.

Video instructions - installing the floor along the joists:

Dry floor screed

Often the subfloor in a frame house can be laid on the ground. Sometimes such a base near the floor is made in houses made of foam blocks or bricks without a basement. As a rule, a dry screed is laid on a specific base. In this case, the base of the floor will consist of the following layers:

• rammed soil;
• sand compacted cushion 100 mm high;
• a backfill of crushed stone 100 mm high is also tamped (for additional waterproofing, crushed stone can be treated with cement laitance);
• This is followed by concrete preparation, which serves as the preparatory layer of the floor (filling height 7-10 cm).

Important: if difficult geological conditions are observed at the construction site (soil swelling, high groundwater levels), then it is better to install concrete preparation with reinforcement.

To reinforce the concrete pour, a rod with a diameter of 8 mm is used. A mesh with cells measuring 150x150 mm is made from it. The reinforcement mesh is installed on mortar piles so that after pouring the concrete preparation, the mesh is located in the thickness of the layer. On each side it should be protected with a two-centimeter layer of concrete. This must be done to protect the fittings from corrosion.

Dry screed technology for subfloors

After pouring the concrete preparation, further installation of the floor can be done after 28 days. Work on installing a dry screed in a wooden house is carried out in the following order:

1. To properly install a dry screed, you first need to make insulation. To do this, insulation made of polyethylene film is laid on the base. Strips of material must be laid with an overlap of 150 mm and placed on the walls of the room to a height of 2 cm higher than the level of the screed. The joints of the film are taped with tape (see video).

Important: try not to damage the integrity of the insulating material. If cuts or punctures appear, patches must be applied.

1. Next, a damper tape is attached to the walls along the perimeter of the room. It is needed to compensate for deformation changes in the floor surface, as well as to protect against impact noise. The width of the tape should be slightly larger than the thickness of the screed (see video).
2. Now you can install the beacons. It is better to use drywall guides as beacons. They are laid on mortar heaps. The pitch of the beacons from the walls of the room is 30 cm, between themselves - along the length of the rule or 1 meter.
3. After the beacons are leveled, granular material, for example, expanded clay sand, is poured between them. Its surface is leveled using the beacon rule.
4. Next, sheets of plywood, OSB, chipboard or gypsum fiber board are laid. They will serve as a subfloor. Before laying the finishing surface, they must be treated with a deep penetration primer.

All photos from the article

In any room, installing a floor is an important step; wooden houses are no exception to this rule. Moreover, it is not necessary to limit yourself only to a wooden floor; ordinary concrete can also be used.

What kind of floor can be in a wooden house?

When it comes to what to make a floor from in a wooden house, the first thing that comes to mind is a wooden floor.

However, this is far from the only option; in general, the following floor installation methods can be distinguished:

• wooden - the most common structure in wooden houses. A subfloor is laid on top of the joists, then a finishing floor, and only then the floor covering. Since the thickness of the floor is decent, insulation can be placed in the space between the joists, so that the heat and sound insulation will be at its best;

• concrete, in this case several options are possible. You can simply remove the old logs and pour concrete on top of the ground (after pouring a layer of thermal insulation and leveling it). Or you can make a thin one, although it won’t be possible to create a thick layer (there is a large load on the joists), you may also need to reinforce the joists, all the work can be done with your own hands.

The load from the structure falls on its foundation. The structure that precedes the final coating and serves as the basis for the insulation is the “subfloor”. The temperature regime of your room depends on how it is installed. If there are cracks left in it, cold air will begin to flow in from below, dampness and a rotten smell will appear in the house.

Description

When choosing a material for the load-bearing beams of the floor structure as a whole, consider the area of ​​the room for which it will be intended. The larger it is, the thicker they are. This factor is explained by the fact that the finishing coating and all materials involved in the installation process must be evenly distributed on them.

How to make a subfloor in a wooden house

There are several options for its formation, but the “dry” method is more often used.

The subfloor is formed according to the following principles:

• According to the lags.
• “Prefabricated”, using dry screed.
• “Adjustable” (on plywood and chipboard).

"Prefabricated" subfloor

"Adjustable" subfloor

If the boards are laid on logs, then they are laid on the following base:

• Beams.
• Reinforced concrete slab.

The adjustable floor is formed on the following bases:

• Lags.
• Plywood.

What do you need to know?

It is laid on the main floor using less hard wood. These include coniferous varieties. These are the following types:

• Edged board.
• Gorbyl

In order to achieve the expected results from the installation, you need to know the following:

• The basis of the entire floor structure is a beam, which is laid on a layer of waterproofing (two layers of roofing felt).
• Rolled protective material or 2 layers of high-density polyethylene are spread on it.
• Logs are attached to the beam, which serve as a frame for installation. They are not brought to the walls, leaving a gap of up to 30 mm. This distance will be insurance against possible soil shrinkage (changes in temperature and groundwater level in the soil) and natural fluctuations in the moisture content of the log during its operation.
• The artificially created free area between the wall must be filled with mineral wool.
• The entire tree must be treated with antiseptics and fire retardants. If ready-to-use materials are purchased, then the cuts made must be protected from moisture and bark beetles.

Do-it-yourself subfloor in a wooden house

To carry out the work, use a board with a thickness of 15 to 20 mm. The source material, properly prepared on milling machines, will create grooves and shoulders on its side. This option will eliminate the need to work with a hammer and nails, which will speed up the assembly process and the tightness of the connection. The rigidity of the structure will not create creaking.

The thickness of the subfloor board affects the distance (step) between the joists. The larger it is, the wider this gap. For example:

• With a board thickness of 40 mm, the step between the lags can reach one meter.
• With a thickness of 35 cm, the step between the logs should not exceed 850 cm.
• If the thickness is less than 35 cm, the step between the lags should not exceed 60 cm.

The correct location of the foundation pillars is of great importance. They are located around the entire perimeter and in the central part of the building.

The thickness of the log is directly related to the spacing of the foundation pillars, since the main beam is attached to them.

The following relationships should be observed between the dimensions of the logs and the pitch of the foundation pillars, expressed in centimeters:

• The logs are 40 thick with a pitch of no more than 900.
• Logs thickness 50 at a pitch of 1100.
• Logs thickness 60 at a pitch of 1300.

Installation of subfloor using plywood

The sequence of work is as follows.

• The beams are placed on a layer of waterproofing.
• Rolled material is placed on them to provide protection from moisture.
• They fix the logs.
• They are lined with 10 mm thick plywood sheets or moisture-resistant boards (MDS, VAT).
• The seams of the connection are covered with construction tape or sealant is poured.
• Cover the subfloor with a layer of vapor barrier.

To insulate against condensation from the room side, the following materials are used:

• Cement mortar.
• Thick cellophane in 2 layers.
• Rolled foamed polyethylene on a foil base (lay with foil to the room) and other materials.

An air barrier must remain between the vapor barrier and the floorboards. The subfloor must be ventilated through holes in the foundation (vent).

Before application, insulate pipes and meters with construction tape. Apply it in layers using a brush, roller or rubber spatula. Pay special attention to hard-to-reach places. After the first layer, self-adhesive tape must be applied to all joints and joints. It will be covered with the second layer. The composition should be partially applied to the wall (its lower part).

There are other materials for carrying out similar work. Rolled foil insulation can be used, which will simultaneously help insulate from noise and retain heat in the room. They are laid overlapping with the metal part towards the room.

Video: Correct installation of the subfloor

Conclusion

This type of “dry subfloor” can serve as the basis for the formation of the main coating. In some cases, for laying parquet boards or laminate, the finished structure is covered with a layer of waterproof plasterboard.

Video: How to make a subfloor from plywood?

Before you start laying the final coating, you need to take care of the rough coating. This rule should never be neglected, because otherwise you risk your entire repair. Remaking the flooring and the floors themselves will require even more effort, expense and time. In addition, such a complex event can cause damage to the entire interior of an apartment or house. So experts recommend taking a close look at the subfloor issue once and forgetting about it for many years.

There are two main ways to create a subfloor, which are divided according to the method and materials used: wet and dry. For wet, concrete or concrete expanded clay is used, and for dry, installation on joists is used.

DIY concrete subfloor

This option is especially popular in standard city apartments, but if desired, it can also be used to furnish a private home. The only question is the foundation.

First you need to create high-quality waterproofing. This can be done using a special film of increased strength. If we are talking about renovations in an apartment on the second and higher floors, we recommend that you pay special attention to insulation. Your manipulations with the floor can cause leaks and affect the repairs of the neighbors below. So be very careful when installing the film. Along the perimeter of the apartment it needs to be supplemented with penoflex with a thickness of 0.5 - 1 centimeter.

The next layer of the subfloor is responsible for the thermal insulation of the room. Previously, polystyrene foam was predominantly used as a material, but recently penofol, consisting of two layers with very good characteristics, has been gaining popularity. The foil layer reflects heat and prevents it from leaving the room, and the polyethylene foam itself is responsible for thermal insulation. Whatever material you choose, it also needs to be covered with a layer of waterproofing film.

The next important stage is pouring the floor with concrete or concrete expanded clay. But you can’t just pour the solution onto the future subfloor. The thing is that this layer will not be able to level itself. That is why, before pouring, special beacons are installed, which will become the basis for leveling the floor. All beacons must be installed level. Only in this case will you be able to get a beautiful and smooth subfloor as a result.

If you want to increase sound insulation, as well as thermal insulation, then pay attention to concrete expanded clay. This material has excellent properties and outperforms conventional concrete in many respects.

Having mixed the solution and distributed it over the floor, carefully level it using the rule, placing the tool on the beacons. Remove excess solution, then leave the coating until completely dry. Your subfloor is ready.

DIY wooden subfloor

To make a subfloor out of wood, you will need some kind of base. If the house already has concrete, then logs can also be laid on it. Just make sure that the concrete screed is level and has no differences in height. Otherwise, your floor will turn out crooked and will creak. Experts do not recommend using wooden blocks as support for joists in recess areas. The problem is that over time the wood will shrink and the joists will lose their stability. And your floors will sag and creak.

To avoid this, you need to pay close attention to the preparatory stage. So, to begin with, the concrete base is leveled using a small layer of screed. The amount of solution is determined by the height difference in the room. After this, leave the resulting base until the solution dries completely.

The next point is laying the waterproofing film, all joints of which must be taped. On top of it, in the place where the logs will be laid, we lay a special soundproofing layer. Foamed polyethylene or cork material is usually used. Without this layer, the floors in your home will make noise with every step.

Now it's time to deal with the lags. But for this you will need timber. Professionals recommend not skimping on joists and using high-quality edged boards. Installation will take you much less time and effort, and your own subfloor will turn out much more impressive and faster. To install the subfloor, you will also need a 25 mm x 100 mm edged board. It can be used not only for installing joists, but also for installing roof sheathing and other general construction work.

The logs themselves are installed on a pre-prepared base so that the layer of soundproofing lining is strictly under them. The height and slope of the joists must be checked with a level.

Now they need to be attached to the base of the floor using corners so that the logs do not move anywhere and serve as the basis for the next layer.

As soon as all the logs are firmly fixed, insulation is laid between them. In no case should it go onto the logs themselves, only occupy all the free space between them.

A floorboard or plywood is laid on top of the joists. This is what the subfloor itself will look like. Working with plywood is much easier, but it has a certain drawback - a relatively high price. A floorboard of the same quality will cost less, but installation will require more effort and more time.

The thickness of the plywood sheet should be at least 22 millimeters, otherwise your subfloor will sag under the weight of a person. In addition, the distribution of furniture throughout an apartment or house can cause a change in the topography of the subfloor. Experts recommend using thicker plywood if you plan to place heavy objects in the room: a wardrobe, refrigerator, sideboard with a lot of dishes, etc.

Sheets of plywood should be laid in a checkerboard pattern to prevent joints from being aligned. Screw the plywood to the joists using self-tapping screws, not forgetting to leave a distance of 2-3 centimeters from the wall for shrinkage and ventilation.

The subfloor is one of the main components of the floor structure as a whole, on top of which, after carrying out the necessary additional previous measures, the final finish chosen by the homeowner is laid. This design can have a different structure and be made of different materials.

Regardless of the chosen design, the subfloor will consist of several main layers, information about which is given in the following table.

Table. Subfloor structure

You will spend significantly less time and effort on arranging such a structure than pouring a screed. In addition, laying wooden supports does not require the use of water, which eliminates the possibility of increasing air humidity in the room being equipped and makes it possible to simultaneously carry out other planned finishing activities. The logs are directly laid on beams, a concrete base or other supports, which will be discussed later.

In this case, the functions of supports for flooring made of boards, plywood or OSB boards are taken over by a structure made of longitudinal logs. The latter can be mounted on supporting posts or beams, as well as on a crown molding. If necessary, logs can even be attached to a concrete base. The specific option is selected in accordance with the characteristics of the structure being developed.

If the room has an impressive area, simply attaching the ends of the logs to the beams will not be enough to ensure the required structural strength. In this case, support posts are mounted between the walls to support the joists. The distance between additional supports is determined mainly by the cross-section of the mounted elements. In most cases, it is enough to make columns in increments of up to 0.8 m. Otherwise, be guided by the characteristics of your situation.

The pillars themselves are made of concrete or brick. At this point, also be guided by your preferences.

Operating procedure

The sequence of arranging the subfloor along the joists is as follows:

• horizontal surface marking is performed. Having determined the required level for installing the floor, laces, fishing line or thick thread are pulled across the location of the future installation of the logs - such markings will allow you to navigate the process of arranging the logs and place them at the same level. If you wish, you can not do this, but then you will have to check the horizontality of the supports at each stage of work, spending more time correcting inaccuracies;
• the surface is covered with waterproofing material, for example, polyethylene film 200 microns thick. This layer will protect wooden logs from moisture from concrete, soil and other sources;
• The optimal step for installing the lag is determined. To do this, you need to know the expected level of load on the future structure. In residential areas, it is recommended to adhere to a 35-45 cm step. If the base cannot boast of ideal evenness, the logs will have to be attached to pre-arranged pads. As such, pieces of plywood are most often used;
• Holes are drilled in the base to accommodate dowels. Next, the dowels are driven directly. Finally, all that remains is to simply screw the logs to the base using self-tapping screws.

If necessary, the space between the joists is filled with insulation. Expanded clay is most often used as backfill, and mineral wool insulation is used as “monolithic” materials. When choosing a specific option, take into account the climatic features of your region and focus on your available budget.

The flooring can be made of plywood, chipboard, OSB or wooden boards. The task is extremely simple: the elements of the rough flooring are laid perpendicular to the joists and nailed to them.

A very effective option that is rapidly gaining popularity among domestic developers. To perform the work, plastic screw racks are used, characterized by high reliability and service life.

This technology allows you to quickly install a subfloor that will not creak in the future. At the same time, you do not have to waste time determining the required thickness of plywood pads and arranging them - the verticality of the legs can be easily adjusted to the required level. After installation, the logs will not come into contact with the base, which is also an additional advantage.

The procedure is as follows:

• in places where screw posts are planned to be installed (necessarily along the edges and along the length of the product with an average step of 0.5-0.8 m), holes are prepared in the logs;
• The log is laid in the right place, starting from one of the walls. A 1-centimeter gap should be left between the wall and the support;
• the support is attached to the base, starting from the outermost screw posts. This type of stand has a hollow structure. To fix it, the performer just needs to drill a hole about 4.5 cm deep in it, drive a dowel into it, and then hammer in a nail or screw in a self-tapping screw.

Finally, the racks are tightened to the level, and work continues in accordance with the scheme for arranging the subfloor on standard joists, discussed earlier.

Adjustable Plywood Subfloors

A rather effective and interesting option for a subfloor is a plywood base installed using special bushings equipped with internal threads. The bushings are inserted into pre-created holes in the plywood. For one sheet of standard size, 16 holes are usually sufficient. As a result, the plywood will seem to stand on legs. Moreover, such a base is characterized by impressive resistance indicators - 1 m2 of subfloor can withstand a load of about 5000 kg.

Dry screed allows you to level out all existing base defects. Moreover, the installation of such a subfloor can be carried out at any desired time of the year.

Prefabricated subfloor with dry screed. 1. reinforced concrete floor slab; 2. wooden beam; 3. flooring made of chipboard, OSB or plywood; 4. vapor barrier (PVC film); 5. expanded clay sand; 6. Knauf gypsum fiber sheet or superfloor element. 7. elastic pad

The procedure is as follows:

• the base is covered with a layer of vapor barrier material secured with adhesive tape. Do the vapor barrier with an overlap on the walls corresponding to the planned height of the future screed;
• between the guides the composition chosen for arranging the dry screed is poured. If the base has large differences, it makes sense to first level the rack beacons on the surface - this will guarantee the correctness and accuracy of the work. In addition, the presence of such beacons will significantly simplify the further fastening of the flooring. The thickness of the backfill layer is selected taking into account the characteristics of a particular situation. On average it is 30-50 mm;
• the backfill is leveled using a long rule or slats;
• The subfloor is laid on top of the backfill and secured with self-tapping screws and glue. For flooring, sheets of plasterboard, chipboard, plywood sheets with moisture-resistant properties, etc. are traditionally used.

Floors on reinforced concrete floors with prefabricated screed made of gypsum fiber sheets for residential and public buildings (Knauf)

Important nuances of installing a subfloor in a wooden house

In wooden houses, the subfloor is most often laid on the ground (otherwise, you can use a suitable option from the list above). The job requirements are as follows:

• the room should be dry and well ventilated. For this purpose, the foundation structure is supplemented with air duct openings. If the basement has damp soil, a waterproofing layer needs to be placed on top of it. Traditionally, clay is used for this - just fill the surface with the material and compact it thoroughly, sprinkling sand on top;
• the base must be waterproofed. When working with foundations, roofing felt is most often used. If desired, you can use other material with a similar purpose.

Before starting work, treat all wooden elements used with a special antiseptic. It is recommended to apply the impregnation in a double layer, maintaining a 5-hour interval. Don't forget to wear personal protective equipment: gloves, respirator and goggles.

Subfloor boards can be laid in accordance with one of the following methods:

• on top of pre-installed H-beams. In this case, the flooring elements are placed in the grooves of the supports;
• on top of T-beams. The boards are laid on the shoulders of the supports;
• onto rough bars. The easiest to use, and therefore the most popular option. It is enough to simply nail the bars to the edges of the beams and lay the boards on top of them.

If the work is carried out in a non-residential premises, you can, if desired, replace the boards with slabs and save money.

All that remains is to lay layers of hydro-, heat- and vapor-insulating material on top of the boards. After this, depending on the preferences of the owner, either the finishing flooring is arranged or the screed is poured.

The vapor barrier is attached over the joists

You have become familiar with the sequence of arranging a subfloor in accordance with the most common and preferred methods. Choose the option that is most suitable for your case, and everything will definitely work out.

Good luck!

Video - Subfloor installation