Thermal insulation of the external walls: complete guide –

The thermal insulation of the house has the role of maintaining a constant temperature and determines a lower cost for heating. Most heat leaks in a house take place through the walls, about 35%. For this reason, we recommend the thermal insulation of the external walls.

This is what the efficient thermal insulation of the external walls and what implies its advantages. In addition, find out how it is possible to choose quality thermal insulation materials, which are the assembly phases and how it is possible to efficiently perform thermal insulation.

Content:

What does the thermal insulation of the external walls mean?

The thermal insulation of the external walls involves the installation of an additional layer on their surface, to limit heat losses in winter and the penetration of hot air inside the summer. Therefore, a pleasant and constant ambient temperature is maintained.

In addition, most of the heat can be lost through the bridge and the roof (about 25%). I prepared a complete guide on the isolation of the bridge, with practical suggestions and useful information.

On the other hand, to prevent heat loss through the external walls, thermal insulation can be performed in two ways:

• Thermal insulation outside – is performed by installing a thermosystem on the facade of the house. For more details, consult this article;
• Thermal insulation inside: this is further explained.

Here are the main situations in which thermal insulation inside is the best solution:

• The house is old, with decorations on the facade that do not allow the application of a thermosystem;
• The cottage is made of trunks and cannot be isolated outside;
• The distance between the house and neighbors is too small and there is not enough space to mount a thermosystem;
• To increase the thermal comfort of the house by completing external thermal insulation.

Thermal insulation of the external walls: advantages

The most important advantages offered by thermal insulation are thermal economy and thermal comfort. The costs for heating a house can be quite high, but can be significantly reduced by limiting heat losses.

The external walls represent the main source of heat dissipation (about 35%) and their isolation limits the exchange of temperature between the external environment and the inside of the house. Therefore, less resources (gas, electricity) are used for heating or cooling of the house and invoices can be much lower.

In addition, large heat variations are eliminated and thermal comfort is supplied both on cold and hot days. In addition, an isolated thermal wall also offers a degree of sound insulation, so that the time spent inside the house is as pleasant as possible.

Materials required for thermal insulation of the external walls

The internal isolation of the walls can be done mainly with polystyrene or mineral wool. Internal isolation with Polistirene is not recommended, because it is a synthetic material and has a low steam permeability. For this reason, sometimes it can cause the appearance of hygrasia and should be avoided for its use for thermal insulation. However, expanded polystyrene can be an optimal solution for external insulation.

We recommend the use of the mineral vate for internal thermal insulation, because it is obtained from natural and recyclable materials, with very good thermal properties. In addition, it is easily mounted, it is not fuel and allows the steam to pass. Another advantage offered by this material is to improve the sound insulation of the house. You can opt for mineral glass wool or light basalt wool (with density up to 40-50 kg/cubic meters).

Differences between mineral glass and basalt wool

Here are some useful information, to help you understand the differences between mineral glass and basalt wool:

• Glass wool – It is easy and has a more accessible purchase price than basalt wool. It has excellent thermal properties, but from a point of view it is not isolated as well as the basalt wool. It is easy to install (usually packaged to the roll), but it makes more dust and it is necessary assembly equipment;
• Basalt wool – It has the price higher than the glass. It has excellent thermal properties and is affected with affection compared to glass wool. The basalt wool is presented in the form of plates. It produces less dust for the assembly of the glass wool, but also in the case of basaltic vate, protective equipment is needed.

Choose the Mineral Vate

To choose the best basalt or glass wool for the internal isolation of the walls, it is necessary to take into account different aspects, as well as the budget you have and the healthy insulation you want. From a thermal point of view, both types of wool are equally good.

In addition, you must know that there is no connection between the density of the Vate and its thermal properties. Instead, the greater the thickness of the vate, the better the thermal insulation is.

Choose a wool with a thermal coefficient λ as possible. The lower the value (W/MK), the lower the loss of heat and the thermal efficiency of the insulating material. We recommend the KNAUF Unifit 035 Glass isolation, which has excellent thermal properties (λ = 0.035), it is fire resistance and has dimensional stability. In addition, we recommend Rocwool basaltic cotton cotton, with extraordinary acoustic and thermal properties (λ = 0.035), with mass hydropbyization and rapid assembly.

If you want high audio insulation, check the acoustic parameters of the mineral screw. They are measured by the air flow resistance coefficient (air flow resistance – AFR). The bigger it is AFR, the better the best wool. Remember that for a quality sound insulation, two elements are needed: an elastic layer that absorbs sound (cotton) and massage. For more details, consult the article how to protect your home acoustically.

To protect the wool from humidity and increase the duration, use accessories for thermal insulation, such as internal steam barriers and sealing ribbon. If you face water infiltration or want to prevent them, read this article, which includes solutions for wet walls.

Main phase for thermal insulation of the external walls

To create an efficient internal thermal insulation with glass or basaltic mineral wool, it is necessary to follow some passages and take into account two golden rules: seal and ventilation!

Assembly of the mineral vate

Mineral wool can be mounted on the surface of the walls in a stable structure over time: between plaster profiles or in a wooden frame. To ensure the stability of the Vate, especially for the glass, you can use a suspended piece rinsed. This keeps the wool in time in time, especially if it is softer. Plastic accessories can also be used, such as mineral wool or fixing.

Seal the mineral vate

Always use a vapor barrier towards the hot side of the house. This has the role of sealing wool: reducing or blocking migration of vapors from home. We recommend the installation of a barrier with the highest SD coefficient, such as LDS 35 or LDS 200. This SD coefficient measures how hard the vapors are through the barrier. Those with SD coefficient over 30 are considered total barriers, through which vapors pass very hard or do not pass at all.

If you omit the installation of this barrier, the vapors that cross the finish layer and reach wool meet the coldest or masonry and condense. If this condensation takes place in the wool, it loses its thermal and sound properties and can obtain an unpleasant smell. In addition, condensation can encourage the appearance of mold and hygraxia. It can also damage the finishes (plaster card) or the wooden structure of the walls.

It is mandatory to use the vapor barrier on the perimeter walls (which are delimited outside) and on the walls of the rooms with high humidity (bathroom or kitchen). In the usual compartmental walls it is not necessarily necessary. But if you have a habit of drying your clothes at home in winter or the bathroom is not very well ventilated, we advise you to mount the vapor barrier and the compartmental walls.

Ventilation of isolated thermal rooms

Thermal insulation significantly reduces the risk of hygrasia, but you have to be careful that the house has adequate ventilation. Often it ventilates the rooms and avoids the accumulation of humidity in the house. In addition, it mounts a high -performance ventilation system in rooms such as bathroom, kitchen and technical room. In addition, in order to prevent water infiltrations in the house, it is necessary to make sure that the hydrlation of the house is performed by specialists.

Thermal insulation of the external walls: practical tips

• When tasting and Monti mineral wool, wearing protective equipment;
• Cut the mineral wool with a knife or a long blade;
• If you mount the wool in a metal or wood structure, prepare the wider stripes with one or two centimeters compared to the distance between the profiles of the structure, to make sure there are no gaps;
• Correct the mineral wool on the wall with special accessories (jerk, cotton dowels, etc.);
• Carefully seal the vapor barrier. Use adhesive solifit strips and double adhesive stripes 2, as well as a sellers for areas where the vapor barrier meets the masonry.

Use high quality materials and respect the assembly phases, to benefit from efficient and durability thermal insulation. Make sure to seal the thermal insulation and correctly ventilate the house.

Author: Raluca Ghetu

Over 7 years of experience in the blog and building materials and over 20 years of experience in the management of projects, budgets, re -enlargement of businesses, training and management consultancy. Passionate about innovation and pay attention to details that bring value. See all articles by Raluca Ghetu