The quality of the facade finish most of all depends on the correct preparation of the base. Without this, even the most expensive paints and decorative plasters will not give the expected effect. Particularly noteworthy is the priming of the surface - an uncomplicated, but very crucial stage. What is a facade primer, how to choose it correctly, and what is it actually needed for?
Priming the facade
Exterior walls are constantly exposed to various negative influences that lead to the destruction of materials. And this applies not only to plastered or painted surfaces, but also facades sheathed with plastic and metal.
The greatest problem is moisture: it soaks the plaster, penetrates into the pores of the walls, under the cladding, as a result of which the finish flakes off, corrosion and mold appear. It is the primer that provides the walls with reliable protection from moisture, forming a thin but very durable water-repellent layer. After impregnation with a primer, the surface does not absorb water even during periods of prolonged rains.
In addition to increasing water resistance, priming compounds also perform other functions:
Why priming the facade of the house at all
For the application of the primer to be as effective as possible, the composition should be correctly selected.
Manufacturers make priming mixtures taking into account the characteristics of those materials from which the walls of buildings are made - brick and concrete, metal, wood, OSB boards and other types of surfaces.
Concrete and brick are durable, do not have a tendency to shedding, and therefore do not need additional strengthening. At the same time, they have a smooth, dense surface, which prevents reliable adhesion between the base and the plaster layer. This means that when choosing a primer, preference should be given to hydrophobic compounds with increased adhesive properties.
For brick walls, use a hydrophobic compound
The metal walls of garages and other similar buildings are also very smooth, but at the same time they are subject to corrosion.
Here primers with anti-corrosion additives and quartz sand content, which give the surface a roughness for better adhesion to the topcoat, are optimal.
For metal surfaces it is important to choose an anti-corrosion primer
The walls of wooden houses are most susceptible to decay, cracking, and pests.In addition, wood is a combustible material and needs to be protected from fire. For such surfaces, you should choose formulations containing fire retardants, insecticidal additives and antiseptics. And the presence of resins in the composition ensures the bonding of wood fibers to each other, which, in turn, reduces the absorbent properties of the material.
Wood needs a primer with fire retardants
Special antiseptic primer
OSB, although it consists of 90% wood, has completely different characteristics. Synthetic resin and wax, which are impregnated with wood chips, protect the material from insects, fungi, and significantly reduce the ability to absorb moisture. And yet, here one cannot do without a primer, because paint and plaster mortar are poorly adhered to a waxed surface, and a small percentage of absorbency is enough to deform the slabs in direct contact with water. Acrylic primers with high adhesion properties are best suited for OSB.
OSB walls should be treated with acrylic primer
Plastered surfaces, as well as walls made of shell rock, foam blocks have a porous surface prone to crumbling .
.. Here reinforcing primers are needed, which impregnate the upper layers of the material, fill the pores and glue the particles together.
Treat porous materials with reinforcing primers
Most of the primers on the market are universal, therefore they can be used on various surfaces. It all depends on the composition of the components, and in order to navigate well in the assortment of primers, you need to study in more detail the characteristics of such compositions by type.
By composition, primers are divided into the following types:
Deep penetration acrylic primer
They form a strong water-repellent film on the surface, resistant to mechanical stress and temperature extremes. Ideal for wood and metal substrates, can be used for the treatment of concrete surfaces, not suitable for materials prone to crumbling.Due to its excellent compatibility with acrylic and alkyd paints, as well as with various types of tile adhesives, alkyd primer is excellent for treating the substrate for painting and tiling;
They are used for all types of surfaces, they can be applied even on a damp base. They dry quickly, provide reliable and durable protection, and act as an excellent base for painting and cladding.
Information on the composition and scope of application must be indicated on the packaging, next to the application instructions, therefore Before you buy a primer, read everything carefully.
Before starting work, you should accurately calculate how much primer you will need to process the facade. This is not difficult at all.
Consumption most of all depends on two factors - the composition of the mixture and the base material.
On average, primer consumption rates are as follows:
Consumption of a primer for the facade
Consumption of anti-corrosion primers when applied to a metal base is about 60-80 g / m2. More precise values for each specific type are indicated by the manufacturer on the packaging. Next, you should take into account the quality of the surface that will be primed - the more porous the base, the greater the consumption. If the wall material is rather loose, porous and highly absorbent, the primer is applied in two or even three layers.
Additionally, take into account the operating conditions and the type of finish: one layer is enough for siding, facing with stone or porcelain stoneware, for painting or decorative plaster it is better to apply 2 layers, especially if the house is located in a damp area.
For calculations, you need to determine the total area of the facade, multiply it by the consumption rate for 1 m2 and the number of layers. For example, the area of the facade is 75 m2, the base material is cement-sand plaster, it is planned to prime it in 2 layers with an acrylic compound. We carry out calculations:
75 m2 x 0.15 kg x 2 = 22.
Depending on the volume received, select the optimal packing so that you do not overpay too, and a small supply of material remained. For example, FARBITEX acrylic primer is packaged in containers of 3, 5 and 10 kg, so in our case it is best to purchase 2 containers of 10 kg and 1 three-kilogram container.
Deep penetration acrylic primer
Comparative table of facade primers from different manufacturers
|Name||Brief characteristics||Average market value|
Deep penetration soil BOLARS
| Transparent composition on an acrylic base, intended for bases with a high degree of water absorption - brickwork, concrete, aerated concrete blocks. Average consumption is 80 g / m2, drying time is 60 minutes. Packaged in cans of 1 kg, cans of 10, 5 and 3. |
5 kg, tanks of 30 and 40 kg
|520 rubles. / 10 kg|
Primer CERESIT CT 16
|Acrylic compound for for the preparation of concrete, cement-sand, brick surfaces, as well as chipboards for decorative plastering and painting. Consumption is 200-500 g / m2, drying period 3-6 hours. Packing 10 and 5 liters||1180 rubles. / 10 l|
| Polymer-based composition containing quartz sand. |
Differs in increased adhesive properties. Designed for the preparation of concrete substrates for plastering and painting. Consumption 350 g / m2, drying period 3-4 hours. Packaged in containers of 5 and 20 kg
|518 rubles. / 5 kg|
| Universal composition for deep penetration. |
Designed for all types of substrates for tiling, painting and decorative plaster. Consumption is 70-100 g / m2, drying time 30-50 minutes
|720 rubles. / 10l|
| Alkyd primer used for processing wooden facades. Contains antiseptics. Average consumption 100 ml / m2, drying time 10-12 hours. |
Packaged in containers of 1, 2.5, 5 and 10 liters
|2505 rubles. / 5l|
Despite the adhesive properties , primer mixtures do not fit well on surfaces covered with dust, soot from exhaust gases, oil stains. Detached and crumbling areas are also not subject to priming, since they will begin to crumble during the application of the composition. In addition, the primer does not mask irregularities and cracks, and therefore all defects will be visible under the finish.
The surface is prepared according to SNiP 3. 04. 01-87. To begin with, they clean the facade of old plaster or paint, and repair cracks, if any.
Removing the old plaster
The areas that are blackened from mold must be cleaned with a metal brush and treated with a chlorine-containing preparation (you can take the usual "whiteness") .
.. Remove oil stains with any solvent. Metal elements are also degreased and cleaned from corrosion.Small areas of rust can be sanded with coarse sandpaper, but if a large area is affected, it is better to use a metal brush or drill with a grinding attachment.
Finally, the base should be cleaned of dust in any convenient way.
Metal brush with scraper
Grinding attachment for drill
SNiP 03.04.01-87. Insulation and finishing coatings.
SNiP 3. 04. 01-87
Alkyd compounds are usually ready-to-use, and you do not need to dilute them, moreover, not every solvent is suitable for them. But acrylic-based primers can be diluted with plain water. When is this done?
If the primer is sold in a concentrated form, the instructions for use must indicate the proportions for diluting the solution with water.
They may differ from manufacturer to manufacturer, so carefully study the information on the packaging. It is impractical to apply undiluted composition, since this will significantly increase the cost of repairs.
Dilute the soil
Important! The diluted concentrate must be used in full on the same day, since its quality will noticeably deteriorate in a day. Such solutions cannot be stored, even in tightly closed containers. It is also not allowed to pour the remnants of the diluted primer into a container with a concentrate.
Experienced plasterers dilute the usual primer with water to save money when treating large facades. But only if the walls are concrete or brick, and the base is prepared for plastering or painting. Surfaces prone to shedding cannot be treated with diluted primer, especially for putty and decorative plaster, since a weak content of binders will cause the materials to peel off. When diluting, the mass fraction of water should not exceed 10% of the amount of soil.
Dilute two-component compositions according to the manufacturer's instructions
For For priming the facade, a roller with a telescopic handle and a medium-width paint brush are most often used, with which hard-to-reach areas are treated.
Additionally, you will need a wide plastic tray where the primer will be poured.
Roller with pallet
Step 1. Before use, the soil in the container is thoroughly mixed to distribute the components evenly. Pour a small amount into a plastic tray.
Stir the primer
Pour the primer into the tray
Step 2 .
The facade is processed in squares or in wide stripes, starting from the corner of the building.Take a roller, dip it in the solution, roll it out on a pallet for uniform impregnation and begin to prime the wall in a horizontal or vertical direction. It is necessary to apply the primer evenly so that there are no dry and semi-dry areas. At the same time, it is also not worth applying the solution too abundantly - the excess will drain to the ground, and you will only increase the material consumption.
Priming the facade
Areas around openings, in inner corners, at joints with protruding elements of the roof are primed with a paint brush. Splashes on glass or other elements that cannot be painted are immediately wiped off with a damp cloth, since it is more difficult to get rid of them after drying.
Step 4. When finished, leave the surface to dry. Depending on the composition and air temperature, this will take from 2 to 6 hours for an acrylic primer, and about 10-12 hours for an alkyd one.
The second coat of primer is applied in the same way after the first is dry. The interval between priming the facade and finishing should not exceed 48 hours. When performing priming work, the air temperature should be in the range from +5 to +30 degrees, and the air humidity should not exceed 60%.
After completing priming, tools should be rinsed immediately with water. Dried soil splashes from the surface can be removed with a solvent or with vinegar essence.
To do this, you need to drip a little product onto the stain, wait a few minutes and wipe it off with a hard sponge.
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