Laying tiles on a wooden floor: preparing the base

Laying tiles on a wooden floor is not the best option in many ways. It's all about the completely different characteristics of two materials - ceramics and wood:

Ceramics require a strong static base, and wood changes its dimensions within significant limits with changes in humidity and temperature. As a result, the tiles separate or crack during active movements.
For normal operation, wood needs air, which does not pass through dense tiles and water-repellent glue. This situation causes the wood to quickly deteriorate.
The service life of wood without repair is several times shorter than that of tiles. Tiles usually cost a lot. And it’s annoying to lose a good coating because you need to change the substrate.
The weight of ceramics and mortar (glue) is several times greater than the weight of wood. If you do not pay attention to this, the mass of the new finishing coating may exceed the strength capabilities of the boards or joists. As a result, the floor will collapse. Therefore, it is advisable to minimize the load - choose tiles of light weight, and also increase, if necessary, the load-bearing capacity of the wooden floor (install logs more often or take boards of greater thickness).

So if you have a choice, try to abandon this idea. If you still decide to lay tiles on a wooden floor, be prepared for the fact that the amount of work will be large.

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The first important rule: tiles should not be laid on a new wooden floor, in a new building or on a new floor. At least several years (one, or better yet two years) must pass, during which the main shrinkage occurs.

If the base is not strong enough, the boards will bend and the tiles will bounce off.
Before laying the tiles on the floor, it is necessary to carry out preparatory work. Their main task is to create conditions acceptable for both wood and ceramics. There will be several stages, and as a result the foundation must meet the following requirements:

Air access to the wood is ensured.
The load is distributed evenly and is not excessive.
The base is motionless.

In bathhouses, the need to lay tiles most often arises in the washing room: constant humidity creates ideal conditions for the development of rot and fungi. That’s why they try to protect wood with ceramics. In other rooms, it is better to consider other flooring options.

Insufficiently well-done waterproofing will cause boards and slings to rot from water.

Assessing the condition

The first step in the room where you plan to lay tiles on a wooden floor is to disassemble the floor: remove the boards. Next, a careful and meticulous inspection of all components of the structure is required: beams, joists, boards, insulation, water and vapor insulation. All the components of the pie.

If there are any signs of destruction, they must be eliminated. When inspecting the wood you can see the following:

Rot. There are many types of this lesion: dry, white, soft. This is the result of the activity of wood-destroying fungi. The type of destruction varies, but in any case the tree becomes soft. The condition is checked simply: if you see any changes in color or structure, drive the tip of an awl into this place. If it goes in and out easily, the wood is destroyed. The affected areas must be removed. If a small fragment is damaged, remove it, capturing some of the healthy tissue, then treat everything with antifungal compounds. If the damage is significant, the structural elements are completely removed, adjacent and new wood is also treated with antiseptics.
Wood-boring beetles. It is mainly the larvae that destroy the tree. They gnaw through numerous passages, significantly reducing strength. The approach to the problem is similar; if the damage is significant, the floor fragment is replaced, thoroughly treated with special compounds. And all bug exit holes are treated especially carefully.

These are the “surprises” you can see when you remove the floorboards

Many types of fungi that destroy wood can only develop in conditions of sufficiently high humidity - at least 20%. In dry rooms this occurs due to unsuccessful waterproofing. Therefore, we check the condition of the waterproofing materials along the way. If there is damage somewhere, we eliminate it and, if necessary, lay/apply another layer of insulating materials. Only with effective waterproofing will a wooden floor last a long time: fungi simply do not develop if there is insufficient humidity, even if there are spores in the wood.

Read how to fight fungi in a bath here.

Fiberglass mesh

Reinforcement of floor screed is possible only with impregnated fiberglass mesh. Impregnation allows them to withstand the effects of the alkaline environment formed in the thickness of concrete.

The material for the reinforcement is threads containing aluminoborosilicate glass. The performance qualities, characteristics, and scope of application are the same as those of polypropylene mesh.

The downside, although insignificant, is that it is undesirable to use fiberglass in rooms with a possible risk of fire. The critical temperature for fiberglass reinforcement is 150°C.

Strengthening, leveling and processing

If the logs are laid in increments of more than 50 cm, additional ones must be installed, otherwise the structure will not support the weight of the new floor covering. When installing new elements, do not forget to treat them with antiseptics and fungicides.

Next, check the floor for horizontalness. This is done using a good building level. Usually there are deviations: shrinkage is usually uneven, in some places it will shrink more, in others less. All deviations are corrected: the lags are leveled. The excess is cut off with a plane, to increase the level, wedges are hammered under the joists or pieces of bricks and other materials are placed. In some cases, it is not possible to push anything down, then they stuff a board on top, removing the excess height with a plane.

The joists must be leveled

The next step is antibacterial and antifungal treatment. For a wooden floor under tiles, you need to find a composition with the longest period between two treatments. Then, according to all the rules, all wooden elements must be processed.

For baths, many people prefer to use only natural impregnations. The most reliable way is impregnation with hot drying oil. For normal protection it must be carried out several times. At least three, and preferably five. A new layer of hot drying oil is applied after the old one has dried. You can check this by touch: the surfaces should not stick.

Treatment with hot drying oil is an effective method of antifungal treatment

When processing, make sure that the drying oil does not cool down. When hot, it destroys spores, bacteria, larvae, and also becomes more fluid, penetrating deeper. So high temperature is the key to effective protection.

When heating drying oil, be careful: even vapors can flare up. Therefore, they heat the drying oil not on the tile, but above the tile, and keep a piece of tarpaulin or felt nearby to quickly cover the container that has caught fire. As soon as the smell of drying oil intensifies sharply, remove the heat source - a couple more moments and the vapor will flare up.

Types of reinforcing elements

Reinforced mesh to create screeds is used in several variations. Each of them is acceptable to provide surface reinforcement with the best performance under certain conditions.

Metal fittings

Metal grid. Made from thick steel wire, grade VR-1, diameter up to 3 mm, welded mesh. The strength of the laid foundation depends on the size of the cells; the smaller the cells, the better. Under the screed, a different mesh of this format is used, most importantly, it is reliably welded. For large rooms, it is better to use a grid with 100x100 cells. Metal mesh is produced in rolls when the wire thickness is 2–3 mm, if more, then in sheets.
Plastic mesh. Reinforced when the layer thickness does not reach 80 mm. The material is based on polypropylene. It is elastic and, unlike metal, less susceptible to deformation. The mesh stretches, but the quality does not change; when it shrinks, it will increase slightly in size, but the screed will retain its properties. An important advantage over metal is its weight; the mesh, rolled into rolls, is light and easy to transport and install.
Fiberglass. A popular material is fiberglass, or more precisely fiberglass. It has many advantages, primarily over metal: it is not subject to corrosion, it is lightweight. The material is specially impregnated with an anti-alkali compound, otherwise it will gradually be corroded by alkaline compounds present in the solution. Rolls of mesh measuring 50x50 are easy to transport and do not require special storage conditions.
Using fiber fibre. To reinforce the screed, an original method of strengthening is used. Fiber is a fiber structure with a length of 6 to 60 mm. Added to the screed solution. Composition: metal, fiberglass, basalt-based fiber, polypropylene. Each of the materials has its own purpose: for a light screed, polypropylene is used, if a dense medium is required, then metal fibers (thin wire).

Plastic mesh

It must be remembered that the technical characteristics of the fiber make it possible to avoid the formation of small cracks.

In cases where the surface is exposed to strong external influences, the form for pouring may not withstand and become severely cracked, which should be taken into account when choosing a mesh for concrete screed.

Fibre-based reinforcement

Preparing the boards

While the antibacterial treatment is drying/absorbing, it is necessary to treat the floor boards. If the previously used ones are in good condition, they can be installed again. But be sure to remove the varnish or paint with which they were covered before doing this.

If you have a sanding machine, removing paint is not a problem.

Removal of paintwork is possible using:

Construction hair dryer. Set the temperature to about 200-250°C and direct the air flow to the surface. The paint swells with bubbles, you immediately pry it off with a spatula, a knife with a wide blade, or a scraper. Using a blowtorch is undesirable: the wood overheats, loses its properties and quickly collapses.
Chemical removers. They are available in a wide variety at any hardware store or market. They are a gel-like mass. Apply to the surface with a spatula or brush. After a period of time, the paint softens and is removed with a spatula. Everything is fine, but if you need to treat a large area, a lot of washing is required, and this is not cheap.
Clean off with a spatula or sandpaper. This is the cheapest, but also the most ineffective way. In the sense that it is ineffective because it requires a lot of time and physical effort. Paint can be removed faster if you have a sanding machine.

You should definitely not reuse boards that have been warped or damaged by pests. It's better to replace them. After cleaning off the paint, the boards are also subjected to antibacterial treatment. After drying, you can lay the subfloor under the tiles.

Preparation of the solution

The coating must be glued exclusively using high-quality material. It is sold in the form of a dry mixture, diluted with the optimal amount of water. In the process of forming the solution, expert advice is taken into account:

the process must be carried out exclusively immediately before laying, so that the mixture does not have time to harden;
prepare exactly as much solution as is necessary for laying out a certain area on the surface;
You can use a construction mixer for stirring, but it is advisable to use a regular wooden spatula;
The supply of the created solution is calculated for several hours.

In the process of creating a solution, it is important to take into account all the wishes of the manufacturer in order to guarantee an ideal result.

It is best to mix tile adhesive using a drill with a mixer attachment.

The solution needs to be prepared for several hours of work

You need to create glue before laying

Correctly calculate the amount of glue

Sub flooring

The first step is to carry out insulation. The main requirement for insulation (except for low thermal conductivity): non-hygroscopic material. To prevent fungi and mold from developing, the floor must be dry. Secondly, it must be light: we need to make the load as small as possible. Extruded propylene foam has these qualities. Plus, bacteria and fungi do not multiply on it: there is no nutrient medium for them. The disadvantages of this material are its unnatural origin, the fact that it does not conduct air and is quite expensive.

The second material that can be used is expanded clay. It is, of course, heavier than polypropylene foam, and also more hygroscopic. But it is natural and conducts air.

The most common insulation material for bathhouse floors is expanded clay.

Having chosen the insulation, it is laid out on top of the waterproofing layer. The thickness is such that there is a distance of 5-7 mm to the boards laid on the joists. This is a ventilation gap that will provide the wood with normal conditions and allow excess moisture to be removed.

The floor will now be rough - the finishing coating will be laid on it. Treated old boards are a great option. They are laid across the joists, but not closely, as before, but leaving gaps of 3-4 mm. A ventilation gap is also left along the perimeter, along the walls: about a centimeter wide. These distances will allow the wood to expand as conditions change, and the gaps will then be closed with skirting boards.

Fasteners must be moisture-resistant: stainless or galvanized nails or self-tapping screws. At the points of attachment to the outer joists, they are driven in or screwed in two pieces; for all other points, one is enough.

The laid boards are puttyed if necessary, then smoothed using a sanding machine. Now all the cracks are sealed with polyurethane foam: it is hard enough to bear the weight of the tiles and adhesive and elastic enough so that the wood can expand and contract. After the foam has dried, it is cut off flush with the floor.

When is reinforcement necessary?

A reinforced screed is essentially a type of reinforced concrete product that can withstand various types of loads. The fittings included in the design are intended for:

protecting floors from cracks and microcracks during operation;
subsidence of the concrete base;
extending the life of the floor.

A cracked screed is a consequence of non-compliance with concreting technology and refusal of reinforcement.
In a residential area, a screed is a 4-8 cm layer of sand-cement mortar that levels reinforced concrete floor slabs. In turn, the slabs do not allow loads that deform the screed; they take them upon themselves.

However, if thermal insulation material (mineral boards, polystyrene foam, extruded polystyrene foam) is laid on reinforced concrete floors, reinforcing the floors becomes necessary.

Reinforcement of floor screed in an apartment or house is carried out under fireplaces, stoves, and expected areas of high load. Also in residential premises it is necessary to reinforce the screed with a thickness of more than 50mm.

Waterproofing floors under tiles

The next step is to ensure tightness. The floor is impregnated several times with hot drying oil or covered with latex impregnation. This must be done carefully, sparing no materials: the waterproofing must be reliable. While the impregnation has not dried, roll out the painting mesh on top. The edges overlap each other by about 5-10 cm. This will be reinforcement that will reduce the effect of wood shifts on the tiles.

As an option, you can use rolled waterproofing materials. Often they put parchment paper, plastic film, or use bitumen or paraffin materials. They are also laid with an overlap, overlapping the edges by 10-15 cm and gluing them with tape.

Fiber fiber

The principle of using fiber as reinforcement for screeds is significantly different from mesh reinforcement.

Fiber - fibers of basalt, glass, polypropylene, metal, in dry form are added to the ingredients of mortar or concrete. When the floor hardens, the fiber gives the effect of a durable monolith, protects the floor surface well from microcracks, but will not save you from significant mechanical impact.

The fiber-reinforced screed is laid and leveled along the beacons, just like concrete or mortar for other types of reinforcement.

If fiber is used simultaneously with metal or polypropylene mesh, a super durable coating is obtained.

When working with fiber, you need to add it in small portions to the mortar mixture, waiting until the fibers are completely distributed in a concrete mixer or other container. If you add all of it at the same time, the fiber can bunch up into a shapeless lump.

Rough screed

Now we need to create a rigid base for the tiles - a rough screed. To do this, a metal reinforcing mesh with a pitch of 20 cm made of 3-5 mm wire is laid on top of the waterproofing layer on the prepared wooden floor. Fill with a thin layer of solution. What is the minimum layer of screed? At least 3 cm. A thinner base will crack.

Wet and semi-dry screed

You can use standard cement-sand mortar. You can add additives or add fiberglass to increase its elasticity and strength. For the washing room in the bathhouse, you can choose additives that at the same time make the concrete water-repellent.

Polymer screeds have good characteristics, but their attractive appearance is useless as a rough coating. And the high price calls into question the feasibility of their use.

When using a regular solution, you will have to wait 3-4 weeks for the screed to mature.

One of the compositions of the polymer screed - with liquid glass - can be made with your own hands. To do this take:

two parts of liquid glass;
two parts of washed and sifted coarse sand;
one part water.

Everything is mixed and the floor is poured with this mixture. The result is a coating that is flexible enough to compensate for wood movement. Instead of liquid glass, you can use two-component polyurethane glue.

When laying the screed, try to make the surface as smooth as possible. According to modern building codes, tiles can only be laid on a perfectly level base. If you are making the floor in a washing room or shower room, then a slope towards the drain will be necessary. And it is formed precisely at this stage.

By adding plasticizers to the composition, the amount of water is greatly reduced. Because of this, the “setting” time of cement is reduced to several days.

Read more about how to make a concrete screed in the article “Do-it-yourself concrete floor screed”.

To make it easier to work with concrete, plasticizers are added to the solution. If the surface turns out to be not even enough, you will have to level it (remove unevenness and fill in depressions) and apply another layer of self-leveling mixture. To make the solution more homogeneous, it is advisable to treat it with a concrete vibrator.

After the screed has dried (takes several weeks), the preparation of the wooden floor for tiles is completed. You can start installation.

Dry screed for tiles

It is not necessary to use “wet” screeds in all rooms. For dry ones, you can prepare the floor for tiles using:

moisture-resistant drywall (the most fragile of all the proposed materials, use only in extreme cases);
GVL slabs (gypsum fiber sheets);
CSP (cement particle boards);
moisture resistant plywood.

But this option for preparing the floor for tiles is only suitable for dry rooms - a locker room or rest room in a bathhouse, a corridor or hallway in a wooden house. The tiles of a washing bath, in a bathroom or kitchen should be laid exclusively on a “wet” or “semi-dry” (with additives) screed.

Some people also lay gypsum fiber board, plywood, or fiber board under the tiles.

When using sheet materials, laying GVL, DSP, etc. has general rules. They need to be laid so that the joints of the sheets do not coincide with the joints of the boards or joists. This is only possible if they are placed at an angle of 30-45° to the boards. Moreover, the laying should be staggered - the sheets should be shifted one relative to the other.

The laid slab materials are secured around the perimeter and in the center with self-tapping screws. The distance between the fasteners is 25-30 cm. Then the seams are filled with compounds intended for moisture-resistant drywall. After drying, the seams are sanded. We can assume that the preparation is complete: we begin laying the tiles.

How to lay tiles on the floor in a bathhouse and sauna, read the article “Laying floor tiles in a bathhouse or sauna with your own hands.”

Final stage

While working, you need to periodically wipe the already completed area of masonry with a rag. This is necessary to wipe off any remaining adhesive before it hardens. And after laying the entire flooring, you cannot walk on it for at least two days.

Grouting floor tiles

After the glue has hardened, you can begin grouting the joints. For this, a special moisture-resistant putty is used. This work can be done using a rubber spatula. But first you need to clean the seams from construction debris and dust.

After all the seams have been rubbed, you need to clean the entire floor of debris with a rag. Then the grout is given a day to dry and you can begin wet cleaning.

This completes the tile laying work. You can learn some tricks and installation techniques by watching videos and photos.

Options for preparing floors for tiles

Schematic representation of the “pie” for preparing the floor for tiles.
As you can see, laying tiles correctly on a wooden floor is not easy. It's a lot of work and it takes a lot of time. Is there any way to speed up and make the process easier? It is highly undesirable to skip any steps. There is only one option: if after disassembling part of the floor, you find that there are no “sores” or troubles. The floor is insulated, it is level and there is no need to level it. Then you can immediately begin laying the subfloor from the boards, but be sure to remove the paint or varnish. You should also not skip impregnation with protective compounds and the creation of a waterproofing layer.

You can somewhat speed up the process of laying the subfloor if you use slab materials rather than old boards (we don’t use new ones - they can still crack). Not everyone trusts them: it is unknown how the same GVL or DSP will behave under tiles, and even in a damp room. Therefore, whether to use them or not is up to you.

If you will make a subfloor for tiles from cement bonded particle boards, plywood or gypsum fiber board, they are laid staggered so that the seams overlap. A gap of several millimeters is left between the plates to compensate for the movement of the wood. They are then sealed with compounds for working with drywall. They are fastened with galvanized self-tapping screws, the caps are recessed into the material. When impregnating, creating a reinforcing belt is unnecessary - the slabs themselves are sufficiently rigid, but more attention needs to be paid to waterproofing so as not to create conditions for destruction.

Photo

Combination of diagonal and parallel laying

Layout pattern

Running

Parquet installation

Modular installation

Features of the technology

Reinforcement is a method of increasing the load-bearing capacity of a structure. Particles of more durable raw materials than the main building material are introduced into the surface. Most often, concrete is reinforced, which collapses when dried out, under heavy loads or due to sudden changes in temperature (humidity).

Reinforced screed differs from conventional screed by the presence of additional reinforcing parts inside. The reinforcing structure is ideal for rooms with uneven floors. Using the technology, it is possible to quickly and easily distribute the solution over the surface, and the inclusions will withstand the mass of building material without deformation.

The floor is reinforced with a screed to prevent subsidence under the elastic base. Reinforcement is not necessary for hard surfaces or thin (up to 6 cm) screed. Technology is required for:

insulation of any type;
soil prone to swelling (sand, gravel);
hydro-heat and sound insulation;
rough floor along joists.

Additional elements take on the compressive effect, protecting the concrete from natural shrinkage. If a floating or composite structure is made on the floor, then reinforcement must be used. The inclusions neutralize bending loads.