Some materials have insulating properties. However, they do not all have the same characteristics. So, which insulation to choose for an attic?
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There are many insulators on the market, all of which have many characteristics to take into account: thermal resistance, durability, possible health hazards and price. But which insulation to choose for attic ? Let’s take a look at what you need to know aboutinsulation attic.
Insulators: what are the health dangers?
Most of the materials used for insulation are safe, with the exception of the polystyrene, which poses a problem in the event of a fire. On the other hand, the glass wool and the Rockwool need to protect the respiratory tract during the break, because they are irritating materials. This is an element to take into account when choosing an attic insulation.
Insulation performance and durability
The performance of an insulation is indicated by its thermal resistance (noted R), which is measured in m2.K / W (square meters x degrees per watt). AT material equal, it depends on the thickness. We also indicate the thermal conductivity (denoted by lambda, λ), which is its inverse, but related to the thickness (in W / mK): the lower it is, the better the material insulates.
Cellular glass (inert material) has a very long duration life and can be moved or reused. The cellulose wadding, the fiber of drink where the linen also have a long lifespan. Conversely, polystyrene, duck feathers, and thin reflective insulation will tend not to stand the test of time.
The price of different insulators
Glass wool and rock wool are the least expensive materials, on average 5 to 10 € / m². On the other hand, reed or cellular glass can be expensive, 35 to 40 € / m² for reed and 30 € / m² for cellular glass.
The price of attic insulation, which we will examine in more detail later, must therefore be taken into account when choosing your insulation.
Insulation of the attic from the inside: what kind of insulation?
Insulating the attic from the inside consists of applying an insulating material to the interior part of the attic. It can be done by blowing or by laying panels insulators or insulation in rolls, depending on the type of attic.
Insulate lost attics from the inside
The lost attic designates the non-habitable attic. To reduce the loss of heat, there are two possible isolation methods:
- Blowing insulation : this technique consists of blowing loose flakes of insulation to cover the floor of the lost attic. It is especially useful for isolating hard-to-reach places. It has the advantage of being easy to implement. This method makes it possible to caulk the attic and improve thethermal insulation and home sound.
- Insulation by laying insulation in rolls or panels : this method consists of installing rolls or panels of insulation at floor level to limit heat loss.
For the insulation of roof spaces from the inside, rock wool or glass wool is most often used for economical solutions. For more natural attic insulation, we will use wood wool or hemp wool. In bulk, the expanded polystyrene can also be used.
Insulate the convertible attic from the inside
The convertible attic corresponds to the habitable attic. They have a higher ceiling height. Insulation of convertible attics from the inside is mainly done by installing panels or rolls of insulation at the level of the crawling roofs.
The insulating material is usually placed between the rafters or below the rafters, depending on the type of frame. It is generally applied in two coats thick enough to insulate the attic well. It may also be necessary to set up a screen vapor barrier.
Once again, wool insulation is the most used for.
What insulation for the insulation of the attic from the outside?
Insulation of the attic from the outside (ITE) is recommended when it is necessary to preserve the appearance of the frame. This method has the advantage of being more efficient and of guaranteeing better sealing. It also preserves the interior space of the attic.
However, the implementation of this roof insulation costs more than the roof insulation from the inside (ITI). L’insulation of the attic from the outside is done by the sarking method. It consists of insulating the roof from the outside by:
- Laying a rigid insulating material at roof level;
- Creating a self-supporting insulating box.
Insulating the roof from the outside is suitable for both lost attics and convertible attics. the sarking is usually done using rock wool or expanded polystyrene panels. Better to opt for insulation specifically designed for the insulation of a roof from the outside.
Which insulation to choose for the attic?
To insulate its attic, you will understand that it is possible to use different types of insulation: in the form of flakes, panels or rolls. The most widely used materials for attic insulation are:
- Mineral wool : this type of insulation is designed on the basis of sand and of materials mineral. It has the advantage of being efficient and ecological. Roof insulation is generally carried out with glass wool or rock wool. The price of mineral wool is between 11 and 15 € per m² on average.
- Insulation of natural origin : this type of insulation offers high thermal properties. It can be sheep’s wool, hemp wool or cellulose wadding. To insulate its attic with a natural insulation, it is necessary to envisage between 30 and 40 € per m² for the supply.
- Polystyrene: attic insulation can be achieved with expanded or extruded polystyrene. This type of insulation has the advantage of being affordable. Its price is around 5 € per m² on average.
To have your attic insulated by a professional, it is necessary to provide between 20 and 215 € per m² on average depending on the method used. Blow-in insulation is generally the most affordable, but it is not suitable for all attic insulation jobs.
The form below allows you to request several free quotes for the insulation of the attic, all without obligation.
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