The attic is the space between the roof and the last floor of the house. It can be a real room, in which case the attic is said to be « converted », or even « habitable » or « accessible ».
Fitting out the attic gives the possibility of saving square meters and creating an additional bedroom or a play area. But it is not possible to transform all the attic into a useful space . Indeed, for them to be suitable for conversion, they must have an average height of at least 1.80 m. In addition, the slope of the roof must be greater than 30% and the shape of the frame must be compatible with the creation of a living space. As for the attic floor, it must also be strong enough to support the weight of a floor. If all these conditions are not met, you will not be able to arrange your attic. They will then be said to be “lost”.
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Why insulate the attic?
Insulating the attic is an operation that has multiple benefits, both in the long term and in the short term.
Indeed, insulated attics function as a barrier between the exterior climatic conditions and the interior of your home. For example, in winter, when it is very cold, the warm indoor air rises. If you do not have insulation, it will escape through the roofs. In the opposite case, in summer, the heat will invite itself in your home by the opposite way. Insulating your attic will therefore limit heat loss in winter and limit its entry in summer .
In addition to presenting a big advantage in terms of comfort, the insulation of your attic will allow you to reduce your energy bill and therefore to save money in the long term. In fact, not only will you limit your energy losses, but the insulation will also allow you to heat your home more quickly.
Factors influencing the cost of attic insulation
There are many factors that go into setting an attic insulation budget. Before embarking on the insulation of your attic, it is therefore interesting to ask for several quotes in order to have a better idea of the cost of the project.
The price displayed on your attic insulation quote will depend on many criteria:
- The type of attic : convertible or not;
- The insulation chosen and the method of insulation : blown insulation, roll insulation, etc;
- The cost of labor ;
- The area of the attic .
Attics and their insulation
Insulation largely depends on the type of attic.
The lost attic
This operation is the easiest to set up and will therefore be the cheapest . In general, to insulate this unused space, it will be enough simply to have a layer of insulation on the floor between the attic and the ceiling.
You can do this for an average cost of between € 20 and € 30 per square meter .
To cover the floor of your attic, the technician will have the choice between two techniques: that of unrolling and that of blowing .
If your attic has easy access, the craftsman can install rolls of insulation of the material you have chosen. If, on the contrary, you do not have easy access to this space, it will have to use the blowing technique. He will then blow the insulating material on a thick layer using a machine.
Converted attics isolated from the inside
Insulating furnished attics is generally more expensive, as it involves laying the insulation between the frame and the roof, and not directly on the floor. It is then necessary to provide the material to conceal this insulation.
Count on average between 40 and 50 € per square meter to install this type of insulation.
Insulation from the outside
If you want to insulate your attic without encroaching on the interior surface, there is the possibility of insulating your attic from the outside.
The budget necessary for this type of installation will be much higher: it will take more than 100 € per square meter . If this method is the most expensive, it is because it involves completely uncovering the roof. It is mainly recommended when the roof must be redone, especially in the case of waterproofing problems.
Types of insulation and their price
As we have said, the cost of insulating your attic will depend in part on the material you use for your work. Here are the main insulators you can find.
Glass wool
It is the most used material because it has many qualities . For example, it is a non-flammable and rot – proof product , which is perfectly resistant to rodents. It is the most affordable insulation, since its price is between 4 and 8 € per square meter .
It has only one small drawback: when laying, glass wool is a very irritating material.
Expanded polystyrene
It is one of the lightest insulators . It offers excellent thermal insulation, but very poor sound insulation. On average, this insulation costs around € 10 per m² . It cannot be used alone because it is also very flammable .
Thin insulation
Widely used in attic insulation, thin insulation is made up of different layers of aluminum which return heat to the outside. Its great advantage is that it is light and easy to install . It is found between 5 and 10 € per m² .
Sheep’s wool
Ecological and less aggressive than glass wool, sheep wool makes an excellent sound and heat insulator . It costs between 15 and 20 € per m² .
Hemp wool
It is a 100% natural insulator which offers excellent thermal insulation . It has the advantage of not being harmful to health, even if it is not easy to install. You can find it around 15 € per m² .
Cellulose wadding
Created from recycled paper, cellulose wadding is more and more often used to insulate lost attics. Indeed, it insulates very effectively from heat and noise . However, it has a high price: it will take around 20 € per m² .
As you may have read, insulating your attic is a project that will require a little thought and analysis. You will have to think in particular of the final objective of the use of your attic, but also of the installation technique of your insulation.
To do this, do not hesitate to contact the professionals in your region to discuss with them. Indeed, thanks to their experience, craftsmen are in the best position to be able to advise you and recommend the best option for your project, your desires and your budget.
Likewise, do not hesitate to consult several craftsmen and ask them for quotes. This will allow you to be able to compare the different services offered and to make your choice with full knowledge of the facts.