External insulation
Content:
When calculating the heat loss at home, it was found that losses through the walls on average amount to about 40% of the heat, through the roof - 25%, through the windows - 20% and through ventilation - 15%. According to this simple scheme, the need for high-quality wall insulation becomes understandable. The technology of external wall insulation provides maximum protection of the building from heat loss through the walls, due to the fact that it takes on the cold impact of the environment.
Advantages of external wall insulation
The advantages of external insulation are the preservation of the area of the interior of the building, the protection of the wall from cooling, the increase in the service life of walls made of frame material. With external wall insulation, the load on the bearing walls does not increase, so the pressure on the foundation will remain the same.
A separate and very significant advantage of external insulation is the protection of the wall from freezing. The bottom line is that with internal thermal insulation, the loss of heat from inside the house is limited, but the wall itself still freezes at low air temperatures. A vapor condensation zone forms between the inner wall and the layer of heat-insulating material, while conditions are created for the development of mold, fungi, additional cooling of the wall due to moisture.
The internal insulation that has accumulated moisture does not dry completely even in summer; a permanent zone of moisture accumulation is created, which negatively affects the service life of the walls. With external insulation, the dew point, that is, the vapor condensation point, moves into the heat-insulating material. The wall insulated from the outside does not cool and the heat lasts much longer, its losses are minimized. External insulation easily loses the accumulated moisture, due to this, its heat-insulating properties are easily restored, the service life of the walls increases.
Another important advantage of external thermal insulation is the soundproofing qualities of insulation materials. If in the private sector this is not so relevant, then in a big city this quality plays an important role.
Types of materials for thermal insulation boards
The main materials for the production of plates used in external thermal insulation are mineral wool and polystyrene foam - in everyday life called polystyrene foam. The quality of these materials must be given special attention when choosing heat-insulating boards.
Mineral wool
It got its name because it consists of artificial mineral fibers. Vata is divided into types depending on the origin of the raw material from which it is made. Stone mineral wool is made from various rocks - diabase, limestone, basalt, clay, dolomite, etc. Slag wool is made from blast furnace, open-hearth and other slags, including non-ferrous metallurgy slags.
Mineral wool insulation has a fibrous structure with a synthetic binder. Mineral wool products are made in the form of plates and mats. The thermal insulation layer of the plates is from 50 to 100 mm. Mats are used for installation of insulation on large working areas.
Advantages of mineral wool in good thermal insulation properties and incombustibility. It is also very moisture resistant, resistant to damage - it does not decompose under the influence of moisture, insects. Basalt wool is resistant to decay, temperature extremes and vapor permeable. In addition, mineral wool is easy to install.
Glass wool
This material is similar in properties to mineral wool, but is made from waste from the production of glass. She has increased temperature stability. When working with glass wool, special care must be taken, be sure to work with gloves, avoid getting particles of material on the mucous membranes and especially in the eyes.
Expanded polystyrene
This material consists of small moisture-resistant granules, which under the influence of high temperatures are combined with each other in a cellular structure. The polystyrene granules themselves have a huge number of microcells, because of which polystyrene foam plates are 98% vol. The material is the cheapest available on the market at the moment, convenient to use. Polystyrene foam boards have a thickness of 50 to 100 mm. Polyfoam is also reliable in that it is moisture resistant, so rotting processes do not start in it.
Expanded polystyrene can be of two types - extruded and expanded. The first sectional view has a shallow closed cellular structure. It is often used for thermal insulation of walling, insulation of the walls of damp basements, garages, and other outbuildings. Expanded polystyrene foam has larger ball-like granules. In general, foam has become the most popular heat insulator, due to its affordability and ease of installation. When installing this heat insulator, it is absolutely necessary to use plaster or cladding; it cannot be used in open form.
External insulation methods
There are two main types of outdoor insulation installation:
- bonded thermal insulation;
- hinged ventilated design.
The first method has gained great popularity in our latitudes, mainly because installation of hinged thermal insulation is more complicated technologically, more expensive in material terms and requires expert advice. The installation of bonded thermal insulation is much easier to carry out, there is only a limitation on seasonality - such work can be performed at an ambient temperature of at least + 5C.
Bonded external thermal insulation - the most pragmatic option
The option of bonded thermal insulation is very popular in Europe and is gradually becoming more widespread in our country. This method allows you to reduce heat loss through the walls of the building by 80% from the initial level, which significantly saves money on energy.
The principle of this system is the installation of a monolithic enclosing multi-layer structure, which becomes a shield in relation to the external environment. In addition to protection against heat loss, these designs exclude the so-called cold bridges in insulating structures, do not increase the load on the foundation, and provide maintainability.
A bonded thermal insulation system can be used on buildings with any type of structure - block, brick, panel, frame-monolithic. For the thermal insulation construction to work optimally, the process technology requirements and the quality of the materials themselves must be met.
The process of installing bonded insulation
The bonded thermal insulation system is installed in several layers:
- insulation - heat-insulating material in the form of a plate;
- reinforcement - a mesh resistant to alkali and coated with a mineral-based adhesive;
- protective and decorative layer - plaster and primer.
Each of these layers has its own specific function. The meaning of installing heat-insulating boards is understandable, the reinforced layer makes it possible to adhere the plaster and the heat-insulating board, the primer protects the materials from environmental influences and performs an aesthetic function proper.
Before installing insulation, the wall must be properly prepared. Preparation includes cleaning from dirt and dust, old plaster, eliminating irregularities so that the insulation adheres to the surface as tightly as possible.On the prepared basis, that is, the surface of the insulated wall, polymer-cement glue is applied. Glue should be chosen frost-resistant, with high adhesive ability in relation to different types of plates. The adhesion index of the adhesive to the concrete wall should be at least 1.0 MPa.
Fixing polystyrene boards
Insulation is attached to the glue, fixed with dowels. If you believe the experts in this field, little things in thermal insulation systems do not exist. The dowels must be so reliable as to withstand the load of the thermal insulation system and the strength of the wind. There are 2 types of screw dowels: with a usual expansion zone, 50 mm in length, and with an elongated zone, 90 mm in length. Dowels with the usual expansion zone are used to fix the insulation on concrete and brick walls. Options with extended spacing are more suitable for hollow brick walls and lightweight concrete. Dowels with a head diameter of at least 60 mm are selected.
Insulation boards can be made from various materials, on which the installation process itself will depend. Materials for the production of plates are mineral wool, glass wool, polystyrene foam. The latter material has such an unfavorable property in construction as combustibility, but recently non-combustible types of expanded polystyrene have already begun to appear. You should pay attention to this when choosing materials.
After applying glue to the wall, the plates begin to be fixed. The adhesive is applied in sufficient quantity to fill all the bumps. The insulation plate must be pressed firmly against the wall, while part of the glue is squeezed out from under it and gets under the neighboring plates, thereby strengthening the joints. Openings between slabs can be removed with foam. For large openings, for example, a strip of foam is glued there. Then the plates are fixed with dowels in the corners. The dowel heads and all joints between the plates need to be coated with mastic.
The next in the process is the reinforcing layer. In fact, it is a fiberglass mesh, sometimes metal. An adhesive composition is applied to the plates, pre-prepared pieces of the mesh are embedded in the adhesive, pressed to the plates, then pulled. Try to fasten pieces of a grid with an overlap for reliability. After the glue dries, it is cleaned, smoothed out and the application of the decorative layer is started. Most often it is decorative plasterover which the entire structure is painted. Paint is chosen resistant to weathering.
Insulation of external walls by spraying polyurethane foam
Wall insulation with polyurethane foam is today one of the modern ways to solve the issue of heat saving. Polyurethane foam has many advantages over other materials for thermal insulation. This material is prepared right before spraying on the insulated wall.
The advantages of this material:
- high adhesion to the surface in any of its configurations;
- the absence of seams in the process of work - this significantly saves time, improves the quality of insulation, strengthens the wall itself;
- low thermal conductivity - a layer of polyurethane foam 5 cm thick is similar in ability to retain heat with a layer of 8 cm polystyrene foam or 15 cm mineral wool;
- light weight of the material in the finished applied form - this does not create additional load on the foundation;
- material compressive and tensile strength;
- no need for a vapor barrier - the material is so tight in its structure that it takes over the vapor barrier function;
- windproof properties;
- low moisture absorption - the material practically does not absorb it even in the wettest weather;
- non-toxicity;
- good soundproof characteristics.
PPU and its application
Polyurethane foam spraying is the deposition of a layer of heat-insulating polymer on a surface with any relief, followed by solidification.In a special device, two polymers are mixed - polyisocyanate and polyol, they are foamed with carbon dioxide while heating to high numbers, and the resulting mixture is fed to the spray gun or to the mixer. Through the sprayer, the mixture is sprayed onto the working surfaces under pressure. Pouring is carried out in certain finished forms, after solidification, the material is removed and used according to the purpose.
The process of wall insulation
The walls are insulated with polyurethane foam on the outside in several stages: preparing the walls, applying polyurethane foam, using reinforcing screeds, and finishing.
Preparing the walls means cleaning them from the old coating, plaster, dust, everything that can reduce the adhesion of the material to the wall. Polyurethane foam is sprayed onto the cleaned surface, and the thickness of its application can be adjusted, thus aligning the depressions and protrusions.
Then, a reinforcing screed is applied to the surface of the heat-insulating layer; a fine fiberglass mesh is used for this. The thickness of the reinforcement layer must be at least 60 mm. Then you can lay the finishing materials - siding, lining, panels, paint.
Before spraying, you need to think about protecting all surrounding surfaces from unnecessary application of the material, because it is very difficult to clean polyurethane foam even with strong solvents.
Warm plaster for external insulation of facades
Warm plaster Is a cement-based mixture with added filler. Vermiculite can act as the latter - a light mineral filler, elements of expanded polystyrene, and also sawdust. Warm plaster with sawdust in the composition is not suitable for facades and is used only for interior decoration. Compositions for finishing facades include polystyrene foam, pumice powder, expanded clay aggregate as fillers.
When choosing a heater, several of its properties are taken into account: thermal conductivity, which should be low to maintain heat, hydrophobicity to prevent moisture from entering, vapor permeability - so that the material layer passes water vapor, and condensation does not occur. The presence of porous materials helps warm plaster to maintain the ability to "breathe", to pass moisture and air.
In warm plaster all the necessary qualities are combined. It does not accumulate moisture, is durable, fireproof, and environmentally friendly. As a heater, it can be used for finishing facades, including those decorated with decorative elements that need to be preserved, for warming slopes, pouring joints and cracks, and masonry.
The use of warm plaster
Warm plaster is quickly applied, does not require the use of reinforcing mesh, (although in some methods it is used for greater insulation strength), it does not require leveling the wall, since it is sufficiently plastic in texture and alignment can be done directly by the material itself. Warm plaster is adhesive to all materials of building structures, biologically stable, vapor permeable.
The technique for applying such plaster does not differ from conventional technology plastering. For greater smoothness, the wall can be additionally sanded with sandpaper or putty.
When can warm plaster be used?
If you pay attention to polystyrene foam, which has a lot of positive properties and is also convenient to use, you need to know that insulation systems using polystyrene are forbidden to be used in some cases, for example, when warming buildings with increased fire safety requirements - hospitals, schools, kindergartens, car washes etc. Expanded polystyrene has low vapor permeability, due to which moisture will accumulate in the room. For some purposes, this is probably a plus.
In contrast to this material, warm plaster is non-toxic, non-combustible, and has high vapor permeability. It is quite possible to use it on the buildings of medical institutions, public buildings of a children's profile.It is suitable for complex facades, through it the contours of uneven surfaces do not appear, as through a polystyrene foam layer. Warm plaster is able to both insulate and give an aesthetic and beautiful appearance to the room.
Warm plaster is multifunctional, it is suitable not only for wall insulation, but also for screeding, sealing joints, potholes, cracks. It can be used to fill places of overlapping flat roofs. It is possible to flood floors with it, while preparing them for floor ceilings and providing thermal insulation.
Cons of this method
The disadvantages of warm plaster are that it cannot be a topcoat; a primer and paint must be applied on top of it. It cannot be sanitizing material, therefore, before applying it, it is necessary to achieve a dry surface. Sound insulation after its application is also negligible.
It should be taken into account that warm plaster has a much higher density compared to the same polystyrene foam or mineral wool, and this indicator is 5-10 times higher. Therefore, insulation using this method requires a solid foundation that can withstand such a load. Further, the thermal conductivity coefficient of this type of plaster is 1.5-2 times higher than that of other materials, therefore, the insulation layer should be 1.5-2 times thicker. And since it can be applied with a layer of not more than 50 mm, it will have to be insulated both externally and internally for better heat preservation.
One way or another, the decision in each specific situation can be taken individually. Advantages and disadvantages - a very relative thing. And heat in the house is an eternal concept.
Finishing coatings for external wall insulation
When insulating walls, there are no trifles - this is what experts in this field say. Plaster, reinforcing mesh, dowels, paints - these are all the little things that you should pay attention to in the same way as the main materials for facade insulation.
Reinforcing mesh
As the basis for the reinforcing layer, glass mesh is most often used, the mesh size is 5X5 mm and weighs from 1,500 to 200 g / m2. The mesh should be treated with a special alkali resistant compound. At the corners of the building, in places where the thermal insulation layer adjoins the architectural details - cornices, parapets - here experts advise reinforcing not with glass, but with a metal mesh with greater rigidity. This is done in order to strengthen the entire insulation structure.
Responsibly, you need to approach the quality of the selected adhesive compositions. The manufacturer recommends glue of a certain brand, composition, which will best provide for the fastening of certain materials. Trying to replace with cheaper options can sometimes be too expensive - even to redo the facade.
Plaster
The requirements for plaster are very strict, since it is this material that is exposed to all the effects of the external environment - fluctuations in temperature, humidity, the action of chemical compounds that are in the air. The outer layer should be resistant to all kinds of influences and be steam-transmitting, not to retain moisture in the thickness of the insulation.
Thin-layer decorative plasters and facade paints are divided into 4 groups:
- polymer cement;
- silicate;
- acrylic;
- silicone.
Cement plasters have high vapor permeability, these are the so-called "breathing" options. They are non-combustible, adhesive to mineral substrates, adhesion coefficient of at least 1.0 MPa, frost-resistant. They are used for insulation with polystyrene and mineral wool. In use are economical.
Acrylic plasters, thanks to the synthetic base, are quite flexible and resistant to deformation. They are used for warming with expanded polystyrene. They are resistant to high humidity, absorb moisture very weakly even in conditions of constant rainfall. Available in a wide range of colors, after release they are immediately ready for use.
Silicate plasters are also resistant to deformation, have high vapor permeability, and have a large selection of colors. Silicone plasters are resistant to precipitation, hydrophobic. Surfaces treated by them are slightly contaminated. This quality can be used when decorating houses in large industrial cities.
In addition to composition, decorative plasters have a different texture. The texture depends on the grain size of the plaster. For example, the bark beetle texture has a grain size of 2-3.5 mm, due to which the surface resembles the bark of a tree. Mosaic plasters have a grain size of 0.8-2 mm. Filler in these plasters is colored quartz sand or small pebbles. When this plaster hardens, it resembles a glass surface.
Finishing work should be carried out at a temperature not lower than +5 C, and within 24 hours the temperature should not fall below 0C. It is forbidden to apply the plaster in strong winds, in the open sun, in the rain, since the plaster needs certain conditions for it to dry, so that it lasts longer.
The requirements for facade paints are similar to the requirements for plaster - wear resistance under the influence of high and low temperatures, moisture, sunlight and so on. The service life of enamels based on organosilicon resins on the market is about 30 years, polyurea - more than 50 years. Choosing the right facade paint can save a lot on periodic re-painting.
External thermal insulation of wooden houses
Wood is considered the most environmentally friendly material for building houses, although now basically such construction can be found only in the private sector. For the external insulation of wooden structures, thermal insulation with protective and ventilating properties is used, and for ventilation, a gap between the outer skin and the insulation is provided.
The process of installing insulation
The thermal insulation of a wooden building consists of the following elements:
- wooden supporting structure;
- inner lining;
- vapor barrier layer;
- insulation layer;
- wind protection;
- clearance for air ventilation;
- exterior cladding.
Before starting work on the insulation of the house, you need to treat the surface of the walls with an antiseptic and a flame retardant - a drug that prevents fire. Existing slots need to be closed, caulked or towed. Then the crate is installed on the wall.
For the crate, wooden bars are needed that are pre-saturated with an antiseptic to prevent decay. The thickness of the bars is 50 mm, their width should exceed the thickness of the sheet of insulation material. For example, with a thickness of the insulation material of 80 mm, the thickness of the bars should be at least 100 mm in order to ensure an air gap. The distance between the bars is made according to the size of the selected insulation, that is, along the width of the plate. Insulation plates are laid in the openings between the bars, then fastened to the supporting wall using anchors.
Vapor barrier
Before laying the insulation, a vapor barrier layer is mounted. Vapor barrier materials are selected according to the type of construction and method of installation. The vapor barrier materials themselves are of the following types:
- aluminum foil with a layer of polyethylene;
- polyethylene reinforced mesh covered with a film;
- polymer coated kraft paper;
- Kraft paper with aluminum foil;
- polymer fabric with double-sided lamination.
You can mount the vapor barrier both vertically and horizontally from the inside of the heat-insulating structure. Installation is done using galvanized nails or a stapler. The joints of the vapor barrier layer must be completely tight, the film must be intact, otherwise water vapor will be allowed to move, moisture will accumulate inside the structure. The seams between the pieces of vapor barrier are sealed with special butyl rubber based tapes. Also strips of material can be overlapped.
Next in the process are installed insulation boards, expanded polystyrene or mineral wool, from the bottom up, the insulation is fixed with a dowel-fungus.Waterproofing is mounted on the insulation - a special membrane, which is attached using a building stapler. These can be materials such as: a combined polymer, a film based on kraft paper coated with aluminum, kraft paper with impregnation, three-layer polypropylene. It is necessary to observe the location of the front and back sides of the material, otherwise instead of insulating it will turn into moisture permeable, which will lead to dampness.
The final stage is the fastening of a beam of 50X50 mm with nails and surface lining. Lining can be clapboard, plastic siding, facade panels to choose from. Between the layer of waterproofing and cladding, a mandatory gap of 2-4 cm is left.
