Concrete putties: for interior work and concrete walls

Concrete putties today are presented on the market in a wide variety and are used to protect and repair the base. The concrete surface is quite dense, but under the influence of external negative factors and time it tends to become deformed and become covered with a network of cracks. To avoid this effect and significantly extend the life of the concrete surface, it is protected with various compounds, one of which is putty.

The main functions of concrete putty:

Restoration of the monolith, elimination of defects and protection from further destruction.
Heat/sound insulation of the room.
Leveling the surface before finishing.
Reliable protection of concrete from various aggressive influences (both outside and indoors).

There are different putties for concrete - there are both universal compositions and special substances designed to perform a specific function. When choosing, you should focus on operating conditions, main tasks, features of the concrete surface, etc. But there are some requirements that all types of putties must meet.

The main requirements for concrete putty:

Thixotropy
– the composition must liquefy during use (so that working with it is comfortable and it is possible to create the highest quality coating) and become viscous as it hardens.
Read also: Concrete waste: types, hazard class, recycling
Moisture resistance
– this property is important for a composition that is planned to be used outside or in rooms with high humidity levels (kitchen, bathroom, toilet).

Elasticity
– thanks to this characteristic, the putty can penetrate the pores of the concrete surface and seal them, preventing external negative factors from affecting them.
Durability
to sudden temperature changes, low/high temperatures - important for putty that is planned to be used for exterior finishing.

Standard characteristics of concrete putty:

Complete drying time can vary from 4 hours to 5 days (it all depends on the specific type of substance).
Waterproofing of concrete surface is about 98%.
Frost resistance – up to 35 freeze/thaw cycles.
The time for using the dry composition after it has been diluted according to the instructions is about 2 hours.

Regardless of which putty you choose for concrete walls, it is important to pay attention only to high-quality products from well-known manufacturers, who guarantee that the composition meets all requirements and provides detailed instructions for its use.

Features of the base

Monolithic concrete has certain properties, which is why putty for finishing surfaces of this type must be selected taking into account the characteristics of the material. The main feature of concrete is low water absorption (hygroscopicity), which reduces adhesion with building mixtures (including putties and plasters).

The mechanism for applying such mixtures involves the penetration of the binder into the unevenness and pores of the surface on which they are applied. And in heavy concrete, the pore size is minimal, so the mixtures do not adhere very well to the surface. To solve this problem, quartz primers are used, which are made from fine river sand and a polymer binder. After the binder has set, the surface of the concrete becomes rougher and more effectively accepts the putty.

The problem can also be solved by first gluing a plaster fiberglass mesh to the surface. But in order to completely hide its texture, putty is applied to the concrete monolith in a layer of at least 2-3 millimeters, or even more.

It is also important to select the correct putty compositions for concrete, which will provide maximum adhesion, protection and durability of the finish.

What you need to know about preparation

So, we figured out the types of putties and chose the appropriate material. All that remains is to prepare the tools necessary for the work and prime the walls.

2.1. Working tools and materials

A properly selected tool plays an important role in obtaining a quality result. To prime and putty the walls you will need the following tools:

Wide roller for applying primer to walls;
Brush for priming corners and joints;
Construction mixer, electric drill or hammer drill with a mixer attachment for mixing the solution;
A bucket for stirring and a brush for cleaning it after each batch;
Rigid large spatula (30-35 cm wide) for quick and even filling of large surfaces;
A flexible small spatula (about 10 cm wide) for finishing hard-to-reach places and for applying the mixture to a large spatula;
Corner spatulas for surface treatment in the outer and outer corners of the room;
The rule is 1 to 3 meters long depending on the area;
Bubble level, plumb line and construction pencil for marking;
A sanding machine, fine-grained sandpaper or a construction float for final sanding of walls for painting.

Necessary materials:

Selected putty;
Primer;
Perforated corner profiles for strengthening internal and external corners and arches;
Beacon profiles with a height from the base to the ridge of 6 mm or 10 mm for applying the starting layer, as well as dowels, screws and fastenings for their installation;
Serpyanka fiberglass mesh for puttying joints of plasterboard sheets and cracks in plaster.

2.2. Preparing walls before puttying

Before puttying, first of all, we clean the plastered walls with a hard spatula from deposits of plaster and particles of debris, after which we brush off the dust from the walls with a brush or broom. This will provide better soil adhesion to the surface.

To strengthen the corners, we install metal or plastic perforated corner profiles (corners) on them. We attach them to the same putty, screws or a construction stapler.

In plasterboard structures, we cover the joints between sheets, screw heads, cracks and dents Knauf Fugen

After the first layer has dried, a second one is made, which aligns the seams in the same plane with the drywall, after which the walls are cleaned.

Next, apply the primer evenly with a roller or brush. For wet rooms, soil with antiseptic additives is used to prevent the appearance of mold and fungi.

After the primer has completely dried, it is recommended to apply it with a second layer. In this case, the walls will draw less moisture from the putty. This way the finishing putty will harden more slowly, which will leave more time for its distribution and leveling on the surface.

Vapor permeability

It is very important that the putty meets the requirements for vapor permeability. The general rule is this: the vapor permeability of any building structure should increase from the inside to the outside. Only in this case will it be possible to remove excess moisture from the room through the walls, preventing condensation from accumulating inside the room or in the finishing.

What happens if the exterior finish exhibits less permeability:

Steam is filtered faster through the inner layers of walls than through the outer ones.
The humidity inside the material from which the walls are built begins to rise.
Humidification reduces the thermal insulation properties of walls and leads to condensation accumulation.
In winter, the dew point moves inside the house, as a result of which the wall begins to freeze.

All this leads to the appearance of fungus, mold, deterioration of the indoor microclimate and other problems that can lead to deformation and destruction of the building, as well as problems with people’s health and well-being. The water freezing inside expands and tears the wall material from the inside, causing early deformations and the spread of cracks.

Due to such features, for internal work you need to choose a putty with low vapor permeability, for external work - with high one. Here you need to take into account all the materials that are used in the construction and decoration of walls in order to follow the general rule.

Types of putties

As a rule, when working with concrete, the following types of putties are used:

Cement. This is the most popular type of mixture in question. Its basis is cement, most often grade M-400 or M-500. The positive side is good water resistance. The negative aspects include the lack of elasticity and, as a result, the appearance of cracks after some time due to shrinkage. This concrete putty is used for finishing walls outside the building, rooms with high humidity and working with concrete floors.
Plaster. The basis of this material is gypsum. Due to the gypsum mixture, natural circulation of moisture occurs. Positive features include good thermal insulation, fire resistance, and environmental friendliness. The disadvantage is fragility. This mixture is used for interior finishing. It is not recommended to use this type of putty in rooms with high humidity (bathroom, shower, swimming pool).
Acrylic. The basis here is acrylic. This is a universal putty, it is suitable for both external and internal work. Due to the good appearance of the finished surface, acrylic mixture is often used for finishing ceilings without subsequent painting.

To increase the adhesive properties of the working surface, it is recommended to treat the surface with primer before applying putty. In our case, when working with concrete, it is better to use concrete contact. However, when choosing a primer, you should pay attention to what kind of work: internal or external, it is intended.

Varieties

Puttying of concrete surfaces can be carried out using various compositions, which are classified according to several criteria. Craftsmen usually select materials according to the order of application - starting, finishing, universal. The starting composition is used to eliminate defects and smooth out sharp transitions. Finishing putties are useful for leveling the surface for finishing. Universal views can be used in any format.

Types of putty for concrete according to composition:

Cement mixtures are very popular, suitable for indoor/outdoor use. The main advantage is low cost, the disadvantage is shrinkage, which can lead to surface deformation and the appearance of defects.
Gypsum compositions - used for interior work, are not suitable for exterior finishing and where there is high humidity.
Acrylic putties are universal compounds that are suitable for any application conditions and different types of substrate.
Epoxy - demonstrate increased strength and drying speed, but have the only drawback in the form of high cost.

According to the degree of readiness of concrete putties, there are:

Dry mixtures - before use, the composition must be diluted with water according to the instructions. To mix a high-quality solution, it is advisable to use a drill with a special mixer attachment. Beginning craftsmen are not always able to mix putty correctly.
Ready-made mixtures - they can be used immediately after opening the package. Putties are usually easy to apply and good for beginners, but are more expensive.

Expert advice

Use the following tips to make puttying concrete easier:

do not use a household vacuum cleaner - concrete particles will damage the filter;
to make working with the primer easier, moisten the concrete with a spray bottle;
use the prepared solution within a maximum of 2–3 hours after mixing;
cement putty is distributed over the surface after application;
to treat large areas, purchase dry mixtures rather than ready-made ones;
Level the fiberglass with a plastic spatula, puttying with a metal one;
do not use putty to level the walls - this will significantly increase consumption;
To level the concrete base, apply gypsum plaster before puttying;
on the ceiling, fiberglass is fixed to the starting layer to prevent sagging;
If there are no significant defects or cracks on the surface, do not apply the starting putty, go straight to the finishing putty.

Concrete surfaces can be puttied without prior plastering if they do not require leveling. Concrete contact is required as an initial soil, and universal deep penetration is required as an intermediate soil. It is important to choose non-shrinking plastic compositions. Then the risk of cracking and reduced durability will be minimal.

Surfaces and materials

Before choosing a putty for concrete, you need to analyze the main selection criteria - which surfaces need to be puttied (floor, ceiling, walls, etc.), whether you plan to carry out work inside/outside, what finish the concrete monolith is being leveled for, what is the purpose premises, etc. Today in Moscow and the regions you can find a variety of formulations at excellent prices, so you should choose carefully.

Walls outside

If you need to putty the wall outside the house, then choose cement facade compositions, which are characterized by moisture resistance and high mechanical strength, resistance to sudden temperature changes. The separating layer between the monolithic/panel wall and the finishing can be a layer of adhesive primer (for example, Osnovit T-55).

Cement plaster is usually used as a starting coating, but it is advisable to use an acrylic composition for the finishing (it can also act as a decorative coating).

When choosing an adhesive primer, you need to look at its purpose and the types of compounds under which it can be applied. Most often, exterior finishing is carried out simultaneously with wall insulation.

What the façade structure looks like:

Monolithic wall made of reinforced concrete or reinforced concrete panels.
A layer of insulation (expanded polystyrene or mineral wool), mounted on disc dowels and cement glue.
A layer of cement putty reinforced with fiberglass mesh.
Decorative plaster or facade paint.

Walls from the inside

The inner layer of finishing can be done only with putty, without plaster, but provided that there are irregularities on the surface of a maximum of 2-4 millimeters, and all defects can be removed with putty. If the size of the defects is greater, then first the wall is plastered along the beacons (if there are irregularities up to 5 centimeters) or leveled with plasterboard over a frame made of galvanized profile (if there are defects more than 5 centimeters).

Main features of choosing and using putty indoors:

For dry rooms (corridors, bedrooms, living rooms), gypsum compositions are chosen, which are inexpensive and easy to apply and process.
For the bathroom and kitchen it is better to buy a cement composition.
Acrylic putty is suitable for finishing rooms with high and low humidity; it can be used without a starting layer (but with a primer required), as it evens out small wall defects and is easy to apply.
Gypsum putty can be used in conditions of high humidity, if the room is well ventilated, the top layer is covered with a waterproof finish.

So, in addition to waterproof paint, gypsum putty can be covered with vinyl wallpaper, but in a damp room they are glued to waterproof PVA (and not regular glue), which is applied to the wall and strip of wallpaper.

Ceiling

Finishing the ceiling is not much different from the treatment of other internal surfaces. The rules are the same: minor repairs can be done using acrylic putty, which provides an important advantage: by maintaining a white color after setting/drying, it avoids the need for painting.

A universal mixture or a gypsum finishing mixture with preliminary priming with concrete contact may also be suitable.

Floor

To eliminate cracks and potholes, use cement putty or ordinary cement-sand mortar (mixed in a ratio of 1:2, 1:3). The cracks are opened in advance (widened with a chisel or a light pick), all potholes are deepened, dust is removed, and they are primed with an acrylic penetrating compound.

To level the floor under the finishing coating, polymer-cement building mixtures are used. Self-leveling self-leveling floors are evenly distributed over the surface (including potholes, cracks), the substance is very fluid and creates an ideal horizontal surface.

Basic leveling is also carried out using a cement mixture, but it is better to use a composition based on the same binder on which the future self-leveling floor is made (polyurethane, epoxy). Both types of binders demonstrate a high level of adhesion, adhere well to the finishing coating and seal defects.

Windowsill

Concrete window sills are usually leveled for painting. Minor irregularities can be eliminated with acrylic-based façade putty after thorough priming with a penetrating compound. Here you can do without an adhesive primer, since acrylic adheres well to a concrete monolith after impregnation with a primer based on the same acrylic resins.

If there are serious defects on the surface of the window sill, it is leveled with facade cement putty with preliminary reinforcement with fiberglass mesh. It is advisable to reinforce the edges with a galvanized corner profile.

And in order to achieve maximum strength, the surfaces are ironed - carefully rubbed with cement without adding sand, diluted to the consistency of sour cream.

The final version of putty for wallpaper

For the final stage of wall treatment, gypsum and latex compounds are best suited. The manufacturer's brand matters when choosing putty, along with the cost. The most popular brands among buyers are Vetonit and Knauf.

The fine-grained finishing product helps achieve a perfectly smooth surface. The adhesive strength of this putty is lower than that of the starting putty. But, on the other hand, it is much easier to process it with simple sandpaper. The layer should not exceed 4 mm.

Gypsum mixtures are recommended as more reliable. But often, when choosing a particular product, the main role is played by the opinion of the master who likes the composition of a certain manufacturer.

Those who are just learning the basics of repair are advised to pay attention to universal types of putties that combine the qualities of starting and finishing compositions. However, they will have to pay double the amount compared to previous options.

Consumption

The consumption of putty depends on the substance itself and many factors - on the conditions under which the work is performed, the condition of the surface, preparation, layer thickness, etc. Exact numbers are always presented on the product packaging. But on average, the consumption is 0.7-1.5 kilograms of substance per square centimeter, provided that a layer 1 millimeter thick is made. To obtain accurate values, the indicator is multiplied by the layer thickness, defects are taken into account, etc.

You can make putty for concrete with your own hands - some craftsmen do just that. For concrete, the most suitable composition is considered to be a gypsum-chalk composition, which can be used in rooms with an optimal level of humidity.

What you will need to make your own putty:

Chalk powder – 2-3 kilograms.
Plaster – 1 kilogram.
5% solution of wood glue - usually determined approximately.

How to prepare the material: place the glue in a container, pour plaster and chalk into a separate container, stir thoroughly. Then pour the dry powder mixture into a container with glue, mix thoroughly using a construction mixer or drill with a special attachment. The finished product should be used within 20-25 minutes, as after a longer period of time it begins to dry out.

How to choose a starting putty for walls

When no unevenness or roughness is visible on the walls, you can safely proceed to the final design. If there are dents, cracks at the seams and protrusions on the surface, it is necessary to use a starting putty, in particular gypsum. In order to purchase the material correctly, it is worth finding out which putty is suitable for wallpaper in different rooms.

In rooms where food is prepared, there is high humidity, so it is recommended to use cement-based putty to treat the walls in the kitchen. When the material is applied in several layers, it is necessary to prime each one.

The starting mixture is used in areas where rough leveling is required. It is safe and reliable, plus it is aggressive to other materials.

The thickness of the putty layer depends mainly on the depth of the unevenness and can range from 3 to 20 mm. When purchasing, you should pay attention to the labeling on the packaging. The combination KR is suitable for dry rooms, while the letters LR indicate that the mixture is intended for rooms with high humidity.

Application technology

Applying putty on concrete is quite simple. The main thing is to take into account the characteristics of the surface, choose the right composition in accordance with the size of the defects and the desired result. The work is carried out in several stages, each of which is important.

The process of applying putty to concrete:

Surface preparation is mandatory; it involves thoroughly cleaning the base from the old coating, degreasing (gasoline, acetone or white spirit are suitable). Oil stains are treated twice. Then the base is brushed, washed with water, and allowed to dry.
Priming - a primer is used to improve the adhesion of materials if mesh reinforcement is not intended. The primer is applied with a roller, brush or spray gun in two layers with a technological break for each of them to dry.

Reinforcement - often used when puttingtying walls, when a special fiberglass mesh is used instead of a primer. The material is pressed against the wall, PVA glue is applied on top, it is allowed to dry and they begin to putty.
The putty is applied as follows: sealing cracks and defects with the compound, applying the starting putty with a wide spatula, waiting for the drying time (it can be found on the packaging), cleaning the surface using P80 sandpaper, removing dust from the base, treating with a primer, applying the finishing putty, waiting time drying, sanding the material with P120 sandpaper. Next, two layers of primer are placed on the base, allowing each of them to dry thoroughly, and finishing is performed.

Why is alignment necessary?

Walls are puttied when there are obvious depressions, uneven places, bulges, cracks and other imperfections that may affect the result of the repair work.

If the walls in the room being finished are uneven, dancing, and the discrepancies at different points are more than 3 cm, even the most luxurious wallpaper will not be able to save the situation, since they will:

Fall off.
To tear and burst.
Severely distort a pattern or design.

In the process of repair work, it is impossible to do without puttying, even in cases where the walls are plastered with beacons. All the same, the surface is not smooth enough for wallpapering. Using putty, you can easily prepare walls for finishing, as it creates a smooth surface without the slightest roughness or unevenness.

Putty will help avoid such problems. You just need to choose the right one that is suitable for the base for the wallpaper.

Important Terms

Before you begin leveling with putty, the surface to be treated must not only be cleaned, but also free from cracks, if any. To do this, they must be expanded with a spatula, and the resulting surface must be primed with a roller or brush. After the soil has dried, gypsum plaster should be applied to the wall; for this you can use a trowel or spatula.

Leveling is done with a spatula, and you can create any required layer thickness, usually a couple of centimeters, taking into account the fact that reinforcement will be performed.

The putty must be prepared according to the instructions, but one should not forget that it is necessary to initially place the dry compound in the container, and only then add water, which will help avoid the formation of lumps.

When can you start gluing?

After sanding the surface, you need to clean the walls from dust with a brush and dry rag.
This is done with a vacuum cleaner at first speed. After cleaning the wall, it must be coated with a primer. After drying, it will leave a thin film that will protect the glue from being absorbed into the surface. When the primer is completely dry, start working on the wallpaper.

Having studied all the subtleties of choosing a putty, the surface will be perfectly smooth and durable. You should not miss small nuances from the work; they play an important role in the formation of a solid wall for wallpaper.

Walls with putty and wallpaper have an attractive appearance and a long warranty period.

Putty work

It is quite possible to putty the walls yourself, but in this case there is no need to talk about good results, although the work is not one of the difficult ones. Most likely, skill is developed through time and practice.

Theoretically, the filling process looks like this in stages:

preliminary preparation . The first stage is to clean the surface, dry it, remove greasy areas, old putty, and former paint. Avoid working on dirty or frozen surfaces;

on the contrary, it will reduce the degree of adhesion of any material to zero. Hence, there is a risk of loss of putty in solid layers.;
primer. This stage should not be ignored. Primer of all putty layers including the final finishing layer before wallpapering. This procedure will provide additional strength;
puttying. Based on the purpose of the room, the application of one or another type of putty and the number of layers itself are varied. In this procedure, it is necessary to let each layer dry thoroughly , and then treat it with a primer;

The starting version of the putty is applied in portions. To avoid visible transitions, application occurs with some overlap on the layer in front of it. The tool is held at an angle of 31-36 degrees relative to the surface;
The finishing layer can be applied only after a day. To do this, you should resort to a narrow spatula, which will reduce the thickness of the layer to 2 mm;
final primer immediately before wallpapering the walls.

Principles of puttying corners

Sometimes evenness and clarity of corners are an extremely important component of a repair. To do this, the walls planned for pasting must be leveled. This procedure will seem very labor-intensive for an inexperienced finisher.

Professionals recommend not removing excess material from the corners in order to grout the corner with abrasive to the required condition.

The most effective in this work will be an angled spatula, which operates on the principle of “supporting the wall.”

At home, it is quite appropriate to use a silicone tube or syringe (standard confectionery), which allows you to distribute the required volume of putty mixture. After which the corners should be sharpened with abrasive.

Slope putty

Puttying slopes occurs in the same way as the corners or walls described above . The only difference is that the process itself is very painstaking, so beginners have practically no chance of coping with this task. Professionals recommend using an angle spatula and leveling with abrasive.

Cost of plaster.

The price of plaster includes the volume of materials used (sand, concrete). Hired workers indicate only the cost of their work per m2, without taking into account the costs of purchasing building materials.

The method for calculating the required amount of materials depends on the curvature of the walls:

Smooth walls. The plaster has a layer of approximately 2cm. It is enough to multiply 0.02 m (2 cm) by the “square” of the surface to be plastered to obtain the volume of the required mixture in cubic meters.

The brand of cement also matters: for example, M-500 requires 5 buckets of sand. This means that 1/6th of the volume is cement. Accordingly, the result must be divided by 6 to find out how much cement is needed and calculate its cost.

By multiplying this number by 5, you can find out the required volume of sand.

Curved walls. The consumption of the solution increases significantly if the walls are curved. They can be curved, concave, or inclined.

It is impossible to reliably accurately calculate the need for mortar in case of severe curvature of the walls. It’s easier to do the following: calculate the volume of plaster in one layer (as if the walls were smooth), and then add to them the approximate volume of areas requiring thicker plaster.

You can buy the components of the mixture in a deliberately smaller volume in order to subsequently purchase the missing quantity (when there are not many unplastered surfaces, it will become easier to accurately calculate). This will help you avoid buying extra material.

Workers performing plastering work charge per sq.m. But this does not apply to special situations. For example, plastering of slopes and corners is charged per linear meter, not per square meter. This is due to the particular complexity of the work.

The way to save money can be as follows: you can plaster the walls yourself, and order more precise and scrupulous work to be done by professionals.