Do-it-yourself facade insulation with foam plastic

Recommendation points

• Preparing the walls
• Fastening the basement profiles, starting strip
• Installation of insulation boards
• Preparing the adhesive
• Apply glue to the plates
• We glue the insulation
• We fix the insulation boards with dowels
• Reinforced waterproof layer device
• Making auxiliary reinforcing mesh layers
• Install punch corners
• Making the main reinforcing layer
• General recommendations for facade insulation

In this article you will find a detailed description of all stages of work, as well as practical advice on insulating the facade, you will be able to understand the criteria for choosing the necessary materials, you will find out what you need to pay special attention to when performing external thermal insulation at home.

For the past several decades, mankind has been looking for ways to reduce energy consumption, a significant part of which is heating buildings. To minimize heat loss as much as possible – this is the main task, having solved which, you can count on a serious economic effect.

A new progressive technology, which has proven itself perfectly in all climatic conditions, was found more than thirty years ago – this is the insulation of external walls by the method of bonded thermal insulation. It is improving from year to year, many companies produce a full range of building materials for facade insulation, they constantly conduct research in this area, develop technological maps and guidelines. In some countries, state energy saving programs have been launched, based on the idea of ​​”wet” external insulation of previously built operated houses.

External bonded thermal insulation is carried out using materials with good thermal performance, made in the form of plates and mats, such as: foam plastic, mineral wool, extruded polystyrene foam. The technology of their installation only slightly differs from each other, the basic operations during these works remain the same.

Polyfoam is most often used for these purposes, due to its low thermal conductivity, excellent performance characteristics and significant low cost. The low weight of this material allows you to achieve the design thermal resistance of the outer walls without strengthening the supporting structures and strengthening the foundations, which makes it possible to quickly, efficiently and inexpensively insulate any, even an old building.

Only the wrong choice of materials or gross technological errors can cause problems with the external insulation of the facade. Let’s figure out how to properly insulate a house with foam.

Preparing the walls

The durability and functionality of the insulation produced largely depends on the correct preparation of the base. This stage of work is quite time consuming, but it is simply impossible to overestimate its importance..

Initially, it is necessary to remove from the walls all protruding objects and structures, such as rain gutters, ventilation grills, window sills, outdoor units of air conditioners, lighting devices, etc. It will also be necessary to remove the communications passing along the facade, which fall into the plane of the insulated wall. Often in old exploited houses, the front brickwork has a lot of decorative elements located near windows and cornices, which also have to be knocked down.

Previously plastered walls should be tapped to check for the strength of the exterior finish. Using plumb lines, cords and long rules, general wall deviations from the vertical or local irregularities should be identified. It is convenient to mark problem areas with chalk, so nothing will be overlooked. In most cases, large differences in level are found on the plane, as well as many weakly adhered areas. It is not worth glueing the insulation on such a base – you need, at least, to dismantle the protruding and breathing plaster cakes. With a chisel, you should remove the influx of concrete, as well as mortar protruding from the brickwork.

Particular attention must be paid to the areas where the oil paint coating remains, which has low adhesion and very poor vapor permeability – clean them. It is imperative to remove fungi, mold, rust, efflorescence, fats and other contaminants from the walls.

Large, non-growing cracks and potholes on the surface are primed with deeply penetrating compounds with the help of maklavits and, after complete drying, are sealed with cement-based putties for outdoor use. Cracks up to 2 mm wide do not need to be repaired. Large local depressions can be leveled by gluing pieces of wall insulation.

Attention! If the base has extensive irregularities of more than 15 mm, then it should be primed, and then leveled along the beacons with special plaster compounds..

When the walls are leveled and dried, the communications have been laid and sealed, the external brackets are lengthened, all wet works inside the building are finished, such as pouring screeds and plaster, the roof is arranged and waterproofing is made – you can completely prime the surfaces and proceed directly to the insulation.

Attention! If communications closed under the insulation are placed on the facade, then in order to prevent possible damage during the subsequent dowelling of the foam, it is recommended to mark all their routes on the detailed plan. You can also take photographs against the background of an unfolded tape measure relative to the enclosing structures.

Fastening the basement profiles, starting strip

According to the project, we determine the lower point of the insulated plane, then, using the hydro-level, we transfer this mark to all internal and external corners of the building, after which we connect them with a coated cord, thus obtaining a starting line. According to the resulting markings, a basement profile is installed, which serves to hold the first row of insulation boards, since they have a very serious movement on the wet glue. The starting bar itself is selected according to the size corresponding to the width of the insulation, and is fastened with dowels with a diameter of 6 mm at intervals of 300–350 mm; it is recommended to put on washers on the “quick assembly” nail. At the corners, the starting strip is joined by the method of oblique cuts or using a corner connector. Plastic end and connecting elements are placed between the sections of the basement profiles to compensate for thermal expansion.

Attention! It is forbidden to overlap the basement profile.

Installation of insulation boards

Preparing the adhesive

The prepared adhesives should be used within 1.5–2 hours, so they are mixed directly on the construction site in the amount required for work. The required amount of water is poured into a volumetric plastic bucket, after which the dry mixture is gradually poured into it and thoroughly mixed with a low-speed drill with a nozzle in the form of a frame until a homogeneous mass without lumps is obtained. For about five minutes, the solution matures, after which it is mixed for another minute or two. If the ready-made adhesive mixture thickens a little during operation, it just needs to be mixed.

Attention! Do not add water to thinned glue..

Before starting work, you must carefully read the recommendations for the use of a specific glue from a specific manufacturer.

Apply glue to the plates

Depending on which differences in the plane must be compensated for, one of the options for applying the adhesive solution to the sheets is selected.

If the irregularities on the wall are up to 15 mm, then a strip of mixture with a height of about 20 mm is applied along the perimeter of the slab, 20 mm from the edges, and then in the middle of the slab (usually 0.5 m²) 5-7 beacons about 100 mm in diameter are evenly superimposed.

For base defects up to 10 mm, glue strips are applied along the perimeter, as well as in the middle of the slab. The width of such strips is about 30–40 mm, their number is determined so that during installation the glue covers about 50–60% of the sheet area. It is important to remember that during pressing, the mixture will be distributed between the wall and the foam..

Attention! The strip of glue around the perimeter of the slab should be intermittent so that closed air pockets do not form.

When installed on a flat base, with differences of less than 5 mm, the insulation is coated with a continuous method. For this, a spatula-comb with a tooth size of 10×10 mm is used..

We glue the insulation

After applying the mortar, the boards must be glued within 20 minutes. Sheets are applied to the installation site with a slight offset, about 20–30 mm, then they are pressed with a rule or a long half-trowel into the plane of neighboring plates. From the surface of the base and from the inside of the insulation at the outer corners, it is immediately necessary to remove the protruding glue. With a level, it is necessary to check the verticality of the installation of each sheet, it is convenient to control the direction of the plane either by reference threads or using a rule. All sheets are tightly pressed against each other, the distance between them should not exceed 2 mm, therefore it is necessary to ensure that the glue does not get into the seams. If, nevertheless, gaps have formed, then they are filled with strips of insulation, or blown out with polyurethane foam. The permissible difference at the joints of elements can be no more than 3 mm in thickness.

Attention! After gluing, the insulation cannot be moved, otherwise the strength of its connection to the wall will be violated. If a serious adjustment is necessary, the sheet must be removed, cleaned of glue and mounted back to a fresh solution on a plane.

The insulation on the wall is mounted from the bottom up, the first row of sheets rests on the basement profile. It must be very carefully aligned in relation to the plane of the base. As a rule, it is most convenient to install the first and last sheets of the row, and pull a control cord along their upper outer edge to help glue the rest of the plates.

The vertical joints of the sheets of each subsequent row must be tied up, offset from the previous one by at least 200 mm, or better by half the slab, that is, the insulation is mounted in a “checkerboard” pattern.

It is very important that vertical joints near windows and doors do not line up with side slopes. The connection must take place above or below the opening, the offset must be at least 200 mm. L-shaped elements effectively prevent the formation of cracks, usually coming from the corners of the openings.

If there is a connection of various materials on the base, for example, an extension made of foam concrete or OSB adjoins a brick wall, then the insulation plates should not be joined in this place, it is necessary to provide an offset of at least 100 mm. The same applies to areas where protruding / recessed structural parts of the facade are located under one plane of the insulation – the differences in the base should be covered with plates of 100 mm or more.

On the inner and outer corners of the facade, it is necessary to make a serrated connection of the plates. The insulation of the corresponding rows should wedge into the plane of the adjacent walls, which will prevent the formation of a long vertical seam, which is very prone to cracking. At the outer corners and slopes, the slabs are mounted with a release sufficient for dressing. After the corner has been formed and the glue has set, the insulation can be trimmed and sanded. Slabs are cut under a metal ruler and square with a knife with a wide blade or a saw with a thin blade and small teeth..

When insulating the slopes, the slabs must be joined to the door and window frames using an adjoining profile or a sealing tape made of polyurethane foam. The tape is glued to the box and compressed with insulation by 1/3 of its thickness. If the window is in the plane of the facade, the insulation must go onto the frame at least 20 mm, while the box should also be glued with sealing tape.

If the main wall has an expansion joint, then the insulation boards in this place should also be installed with a gap of 10–12 mm. After that, a polyethylene foam tourniquet is inserted into it, squeezed by 30% of its “free” diameter. It is convenient to have thermodynamic seals of various thicknesses on hand.

We fix the insulation boards with dowels

After the glue has completely set, manufacturers usually indicate a period of at least 3 days, you can start fixing the insulation with dowels. For these purposes, specially designed dowels made of durable elastic plastic are used. They have a wide perforated umbrella-shaped head and a plastic nail or screw-in pin. The length of the fasteners is chosen depending on the thickness of the insulation layer and the characteristics of the base. So the umbrella should go into concrete by 50 mm, brick – 90 mm, blocks with a cellular structure – 120 mm.

Attention! Try not to use dowels with a metal rod, as they cause cold bridges.

As a rule, fastening is carried out in the corners and in the center of the slab, about 6-8 dowels per 1 m². At the corners of the building, near window and door slopes, in the area of ​​the basement, additional fasteners should be installed, located 200 mm from the edge of the plates. The number and spacing of additional dowels is determined by the dimensions of the building, the size of the insulation plates, wind loads and the bearing characteristics of the fastener itself.

A perforator should drill holes of the required depth and diameter, remove dust from it. It is recommended to make holes that are deeper than the length of the rod, about 10-15 mm. Next, a dowel is inserted into the hole and a spacer nail is hammered with a rubber hammer or the pin is twisted with a screwdriver. The disc head of the fastener must be flush with the surface of the insulation, or protrude no more than 1 mm.

Attention! In case of damage during hammering of the plastic head of the rod or the disc head, the dowel should be completely sunk and sealed with sealant, and an additional.

Installation of umbrellas must be carried out strictly perpendicular to the plane of the wall, periodically checking the strength of their fastening for separation.

Reinforced waterproof layer device

Making auxiliary reinforcing mesh layers

The corners near window and door openings must be glued with reinforcing patches made of reinforcing mesh. The size of such patches should be 200×300 mm or more. This operation avoids the occurrence of very common cracks near the inner corner of the opening. The installation technique of the mesh reinforcement does not differ from the device of the main reinforcing layer.

The walls of the first floor are recommended to be reinforced with an additional layer of mesh to a height of at least 2 meters. Such duplication helps to protect the facade from mechanical damage..

Install punch corners

All external corners of the building, including slopes and protruding decorative elements, are reinforced with aluminum or plastic perforated corners, which are produced with mesh strips attached to them. On both sides of the corner to be reinforced, a strip of adhesive composition of such a width is applied so that the mesh is also glued, then the pre-cut perforated corner is tightly pressed against the insulation with a spatula and set vertically or horizontally using a level. The glue emerging from the perforations and mesh cells is smoothed out on the plane of the walls. The connection of the perforated corners is made end-to-end, while the shelf and mesh at the edge of the profiles should be cut at an angle of 45 °. If necessary, the perforated corner can be temporarily fixed, pulled, leveled by inserting nails into the insulation through the perforation holes, after which they will need to be removed.

Making the main reinforcing layer

After the preparation layers have completely dried and all the reinforcing elements have been fixed, the main mesh can be mounted.

To strengthen the insulation, a mesh specially designed for facade work is used. It is made of alkali-resistant low-stretch fiberglass, capable of withstanding design loads – about 1.25 kN per strip 50 mm wide.

To protect the insulation and install the reinforcing mesh, a special mixture is used, which is often different from the one on which the plates are glued to the walls. In this case, the solution for reinforcement is prepared in the same way as the adhesive.

Before starting work on reinforcement, the glued insulation plates are sanded with hand graters with coarse sandpaper. Thus, possible differences at the joints of the sheets are eliminated. Before applying the solution, the surface must be free of dust, sanding products and other contaminants..

The mesh is cut into strips equal to the height of the walls. An adhesive composition is applied to the wall with a vertical strip equal to the width of the mesh fabric. The mortar is applied in a uniform layer about 2 mm thick. The most convenient way to do this is to use a metal grater or a grater. The prepared mesh is unwound over the entire length of the surface prepared for pasting, applied to the solution and embedded in it using a grater or a smooth metal spatula. The canvas must be gently smoothed, starting from the middle and moving towards the edges. The protruding adhesive should be leveled on the surface.

Attention! The mesh should not be overstretched and pressed against the insulation, it should be in the middle of the layer.

On the glued reinforcing mesh immediately, using the “wet on wet” method, it is necessary to apply a second layer of mortar with a thickness of at least 2 mm. Leave a free edge of 100 mm for the subsequent mesh strip to overlap. The second layer is more carefully leveled; in the finished version, the mesh from it should not be visible. Now the glue is applied next to the already mounted mesh, the new canvas overlaps the previous one by 100 mm, and all operations are repeated.

The next day, the not completely dry reinforcing cake can be sanded with sandpaper, putty on small shells. If it is necessary to level the surface using a rule and an additional adhesive mass, you need to wait until the base reinforcing layer has completely dried.

After about three days, the walls will be completely dry and will need to be treated with a quartz-sand primer, which provides good adhesion for subsequent coats and facilitates the application of decorative plasters. We will definitely talk about them in the following articles..

General recommendations for facade insulation

Wall insulation works in this way are carried out at an air temperature of +5 to + 25 ° C and a relative humidity of up to 80%. Work surfaces at every stage should be protected from rain, strong wind, direct sunlight. To do this, use solid curtains made of dense mesh, stretched over the scaffolding.

Reliable scaffolding or scaffolding should provide access to all sections of one wall and at least several meters of adjacent planes. They must be 200-300 mm away from the building so that technological actions can be performed without hindrance..

Seal window and door frames, external communications and all kinds of brackets with masking tape and polyethylene. Cover the blind area, porch and other building elements with cardboard or foil. The tape will need to be removed immediately after the end of wet painting..

Do not store insulation in direct sunlight, do not let it get wet.

If the wall, glued with foam, has not been covered with a reinforcing layer for a long time, then the plates may turn yellow. In this case, the yellow “dusty” surface must be cleaned with emery before proceeding with the following operations..

Start insulating the simplest wall, or the one that is least visible. Practice technological movements and procedures.

If you have to preserve work for the winter, then the insulation must be fully protected with all reinforcing layers and covered with a primer with quartz sand. All window sills and metal elements used to protect horizontal surfaces – parapets, slopes, etc. should be installed.

Whenever possible, plan the work in such a way as not to interrupt “wet” operations on one wall, especially at the stage of reinforcement and application of finishing layers.

Use only specialized materials for insulating facades using bonded thermal insulation. Polyfoam will be needed specifically for external facade work, it has the necessary indicators of vapor permeability, fire resistance and density – 25 kg / m³. Do not replace styrofoam and mesh reinforcement mortars with ceramic tile adhesive. Use only façade alkali-resistant mesh and high-quality disc dowels. It is better if the whole range of materials comes from one company. Follow all manufacturer’s recommendations.