Warming house of aerated concrete extruded polystyrene

In recent years, more and more popular is the construction of low-rise buildings of aerated concrete. With all the advantages and merits of this material at beginning developers are often the question arises whether it is necessary to insulate the house, built of aeratedAnd if the warm extruded polystyrene foam, then how to do it correctly. Investigated with the help of producers.

Why you need to warm aerated

In order to understand whether or not to further insulate the walls of aerated concrete homes, you must first understand the properties of the wall material.

Aerated concrete is a type of cellular concrete. It is made of quartz sand, lime, cement and water with the addition of blowing agent (alumina powder). By reacting with the lime gasifier, a chemical reaction, which resulted in the "body" of the material formed hydrogen gas, a foaming cement. This leads to the appearance of fine cavities with air. That is, figuratively speaking, concrete - this is an artificial "air" a stone, and the air - a good heat insulator.

Andrew Stallions (Head of the technical department of the company "PENOPLEX"):

Due to the cellular structure and low density, reduced weight, and increase thermal insulation properties of aerated concrete.

For example, the thermal conductivity of aerated concrete, depending on its density (400-600 kg / m3) and strength grade (V2.5-3.5 - blocks D400 and D600) may vary in the range of 0.096 W / m * K to 0.14 W / m * K.

It should be noted that the above coefficients are correct for the material dry. And numbers specified for a single block, and the wall consists of a plurality of blocks. Those. are not considered "cold bridges" (masonry joints) and additional conductive elements that reduce the thermal resistance of the wall. This - concrete bridges, Laying nets, metallic fastening elements used for mounting of facade systems, etc.

Therefore, it is necessary to conduct calculation using masonry thermal conductivity of aerated concrete under certain humidity conditions, depending on the region (humidity area) construction.

Also, because of its porous structure, concrete - permeable. This affects its heat-shielding properties, as increase in moisture content (contained in a pair) leads to an increase in the thermal conductivity of the material and decrease its heat-shielding characteristics.

Also selling blocks have a residual moisture which at least blocks decreases drying.

Andrew Stallions:

Prior to construction should provide design solutions that provide protection from waterlogging blocks. Or forced drying is made of blocks of cellular concrete to stabilize the humidity level performance indicators - not more than 10% by weight.

You can use a heat gun capacity of not less than 2 kW. It is also necessary to protect the units during the construction of the excess moistening, avoiding finding blocks in water and hiding them from rains.

For example, a 1% increase by weight of water saturation increases the thermal conductivity coefficient of more than 3-4%. Installation possible blocks without preliminary drying at low temper moisture (up to 10% by weight) and the absence of precipitation in the production process.

Remember about the so-called operating (equilibrium) moisture content, which is set in the range 4-5% 2-3 after heating seasons. Those. an actual heat transfer coefficient of cellular concrete density of 500 kg / m3 (0.12 W / m * K in the dry state) ≈ 0.14 W / m * K.

The speed with which the drying unit is directly proportional to its vapor permeability and sorption capacity of moisture. The lower the moisture vapor transmission rate above unit and the faster the unit is dry.

Additionally, the use of cellular concrete blocks in wet rooms, without protection against exposure to water can cause excessive vlagonakopleniyu.

From the above, in order to achieve stability, a calculated appropriate, indicator thermal resistance walls (JV 50.13330.2012 "Thermal protection of buildings"), it is necessary to insulate the material impervious vlagonakopleniyu and the harmful effects of atmospheric phenomena.

For example, extruded polystyreneHaving a low thermal conductivity (λ = 0.032 W / m * K) and characterized durability. The question arises because this material has a low water vapor permeability (μ = 0.008 mg / (m · h · Pa) due to closed cellular structure, Would not that steam and moisture contained in it (since aerated vapor permeable) "will lock" in the wall, leading to excess vlagonakopleniyu?

How to deal with breathable walls?

To answer this question, we must consider such a thing as "breathing walls". Often, uttering a phrase to confuse the two concepts - the air permeability of the enclosing structure (Ability to maintain air circulation) and its vapor permeability (ability to eliminate hit the wall pairs outwardly).

Andrew Stallions:

Modern regulations require - air must be updated in the room every hour, on the basis of norms of 60 m³ per person. Even without resorting to calculations, it can be said that no reliable cladding does not provide ventilation in the room at the desired volume us.

Air exchange in the House should support a modern ventilation system.

Go ahead. Inside the dwelling is always a pair - the result of human activity. Respecting civil rule: water vapor permeability of the layers (in a multi-layer wall) shall be increased from the inside out, we are allowing to go excess couple outside. However, modern materials used for decoration, vinyl wallpaper, paint, significantly reduce the water vapor permeability of the walls, as These materials act as vapor barrier.

Andrew Stallions:

Calculations show that a large part of the production humidity (over 97%) is removed via the supply-exhaust system.

Movement of water vapor through the walls - it's a natural physical process. When this amount of water vapor, which can exit from the premises outside or penetrate slightly.

According to the request of p.8.8, SP 55.13338.2011, walling houses must be thermally insulated, vozduhoizolyatsiyu against penetration of cold outdoor air and vapor barrier against diffusion of water vapor from interior. Thus, regulatory prevents the migration of water vapor and ambient air directly through the outer walling. Therefore, for maintaining a comfortable microclimate in the house ventilation is also responsible, not mythical breathing walls. After all the frame houses are also made on the principle of the thermos.

How to insulate a house of aerated concrete extruded polystyrene?

Deciding to warm aerated concrete house extruded polystyrene, it is necessary to clearly follow the recommendations of experts.

Andrew Stallions:

First of all, we need to ensure reliable closed circuit vapor barrier inside the premises. Those. - we will create a barrier to the diffusion of water vapor in the gas concrete and, thus, prevent vlagonakoplenie in a vapor-permeable gas concrete wall, sealed from the outside with a vapor heater.

Insulation thickness determined thermo-calculation (usually not less than 100 mm). This will bring the dew point in the thickness of the insulation material and eliminate the possibility of vlagonakopleniya wall.

The vapor barrier can be used as conventional polyethylene 200 micron thick. For rooms with high humidity (bathrooms, saunas, steam rooms) such an obstacle can serve tiles with steamtight grouting.

Next, proceed to the insulation work on the outside of the masonry. The process can be divided into a number of successive stages:

• Surface preparation.
• Gluing of insulation boards.
• Mechanical fixing of insulation.
• Surface finish decorative layer of plaster.

Let's discuss each of these steps.

Andrew Stallions:

Before insulation the outside wall must be leveled base (allowable surface roughness - 5 mm). It is recommended to extract or forced drying of the walls prior to finishing work on the outside. Installing insulation must be carried out in the absence of precipitation.

After preparing the surface, glue insulation panels to the wall. To this plate with applied adhesive composition is applied to the wall at a distance of 2 cm from the desired location. Then forcefully slid. This is to ensure that the adhesive bond has turned more uniform. For the so-called bandaging insulation boards are glued offset. Tipping is conducted away from the building corner.

To accelerate and simplify the process of adhering to the wall panels made of extruded and foam polystyrene, you can use a special polyurethane adhesive. Such adhesives exhibit high adhesion to various substrates. For example concrete, aerated concrete, bricks, ceramic blocks, etc.

After the insulation is glued to the wall, it is necessary to carry out mechanical fastening plate type dowels and screws 4 of the calculation units. per 1 sq.m. At the corners of the building on the perimeter of window and door openings - 6-8 pcs. per 1 sq.m.

The plaster system is applied as an outer finish - so-called "Wet front."

Andrew Stallions:

For the base layer of plaster, as well as for bonding polystyrene insulation boards need to use special painting and adhesive mixtures. It should be remembered that the basic outer layer of plaster plates reinforced with fiberglass insulation is necessary.

Plastering must be performed at ambient temperature and the base in the range from +5 to + 30 ° C. Do not work in the rain and strong winds. In addition, the materials must be protected from rain, frost and direct sunlight for a period not less than 72 hours. Also not recommended to apply the reinforcement and decorative layer on the surface exposed to direct sunlight.

Thus, creating a sealed heat insulating loop outside the house, we will eliminate all thermal bridges, protect the masonry from blowing, and thus minimize heat loss through the walls, which will improve energy efficiency building. In addition, taking advantage of special technical cardYou can learn about other options for the use of thermal insulation based on extruded polystyrene.

The users of our portal will be interested in the topic, how to calculate the optimal thickness of insulation. And in this video presented a master class for beginners, which are displayed preparatory work for plastering walls with setting beacons.

Discuss the article and read other materials devoted to country life you can on the websiteFORUMHOUSE.

Subscribe to the channel and put the "Like" so as not to miss the next release!