- Imperative: have a global vision of its insulation before starting work
- You want to insulate your attic at € 1?
- ECD: which obligations?
- What rules apply for energy consumption?
- Climatic zones of thermal regulation
- What thickness of insulation to add?
- How to make a good diagnosis of its thermal insulation?
- Analyze the insulation of an existing building
- Insulation: special cases
- How to insulate the attic?
- Low floor: solution for good insulation
- What tax credit rate for insulation?
- 11 powerful solutions to insulate well
- Under crawling insulation
- Exterior insulation under plaster
- Self-supporting panels
- Sandwich panel
- Metal frame
- Dubbing partition
- Insulation by blowing or expanding
- Reported ceiling
- Dry screed
In renovation, isolate your home is a priority. As a result, less expenses, more comfort and a higher value of good in case of resale. But which regulations to apply and which solutions to choose? The answers to these questions and many more!
In France, 19 million homes were built without taking into account any thermal requirements.
Built in the absence of any regulation and any objective of energy performance, the old houses are often badly, even not isolated. The heat escapes from all sides (roof, doors and windows, walls, floors...), the walls in contact with the outside are cold, and it is necessary to superheat the air in winter to obtain a comfort just acceptable. This is at the cost of waste of energy and money and a high rate of greenhouse gas emissions.
Insulation is therefore one of the priority items to be treated in renovation when it is desired to limit heating expenses while increasing both the comfort and the value of his house.
Imperative: have a global vision of its insulation before starting work
The installation of insulation on the walls is the keystone to reduce the energy bill.
But, during a renovation, it is a global reflection that must be engaged. In fact, each position contributes to transforming an energy-consuming house into a comfortable and easy-to-heat living space: organization of rooms, ventilation system, type of glazing, heating method, use of renewable energies, thermal bridge hunting...
These works engage for many years. It is therefore better to undertake them in several phases in order to spread the costs, instead of trying to achieve them all at the same time skimping on prices and quality.
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The feeling of comfort does not depend solely on the temperature of the air. It is influenced by the surface temperatures of the walls. Poorly insulated soil, and therefore cold, requires overheating a room.
Facing south, roof windows are an important source of solar heat in winter. The installation of an awning outside sun can avoid overheating in summer...
ECD: which obligations?
The diagnosis of energy performance (DPE) is mandatory when selling or renting a home and for any new lease of a property.
It assigns a rating - from A to G - to your home based on the energy consumption per square meter. The average consumption in France is estimated at 240 kWh / m2 / year, which corresponds to the E rating.
But the RT 2012 for new homes involves houses not exceeding 50 kWh / m2 / year, the A rating. The DPE also recommends solutions to improve this rating. Even if you are not obliged to do so, there is nothing to prevent you from having a diagnosis made to obtain this information and to guide your renovation work.
More information and answers to your questions on the website of the Ministry of Ecology, Sustainable Development and Energy.
What rules apply for energy consumption?
The main purpose of thermal regulation (RT) is to limit heat loss and thus energy consumption.
Replacing the 2005 version, the new 2012 regulation reinforces performance requirements. But it only applies to new construction.
In renovation, the rules enacted since 2007 in the RT "element by element" (which recommends performances by component: walls, floors, roof) are still valid and less restrictive than those of RT 2012. However, nothing prevents you from to go beyond these recommendations to have a better isolated house.
But in practice, nothing requires you to achieve these performances: the RT specifies that the insulation work remains "at the discretion of the owner"...
In order to have an isolated and comfortable house, the RT "element by element" recommends that each wall of the house is sufficiently thermally resistant to oppose the flow of heat or cold.
Concretely, walls, floors and roofs must prevent the heat contained in your rooms from escaping. The thermal resistance (R, expressed in m2.K / W) to achieve for each type of wall is therefore recommended (see drawing below): the larger the R, the more insulating the wall.
Climatic zones of thermal regulation
In rehabilitation, the thermal regulation "element by element" divides France into three zones (H1, H2, H3) according to the temperatures and sunshine of these.
On the other hand, there are 8 zones in RT 2012, which applies to new constructions.
Depending on the region in which the construction is made, the insulation of the "opaque" walls must reach a certain level of thermal resistance (R). Note that the most sensitive walls, in other words those through which heat escapes most easily, must be the best insulated. Hence the high demands levels set for the attic and underside floors of the roofs.
Once the level of thermal resistance to be attained and depending on the nature of the existing wall, the thickness of the insulation varies. For example, in the case of a roof with done up roof, it is necessary at least to lay a thickness of 16 cm of glass wool to reach a R equal to 4...
The size of the openings according to their orientation plays an important role in the thermal performance of a house.
For example, in the north, only install service rooms and reduce the size of the windows.
What thickness of insulation to add?
To achieve the recommendations of RT 2012 (or exceed them), you must install the insulation so that the thermal resistance of the wall + insulation assembly is at least equal to the recommended value.
Attention, when a wall is composed of several materials or several layers (example: plaster + blockwork + paneling), the thermal resistances are added.
Flexible, rigid, bulk insulation, natural insulators, animal or vegetable, the choice is vast, but the most important data is once again the thermal resistance (R) of the product: it is indicated on the labels of all insulators.
For example, the exterior walls must have a minimum thermal resistance of 2.3 m².K / W as part of the RT 2012. Whatever the current resistance of your walls, this performance can be exceeded with 9 cm glass wool, extruded polystyrene, vegetable or animal wool; with 8 cm of polyurethane foam or 10 cm of expanded polystyrene.
How to make a good diagnosis of its thermal insulation?
Non (or poorly) insulated walls are responsible for 20 to 25% of the losses. Before starting insulation work in an existing building, it is necessary to diagnose the thermal resistance of the walls.
Go around your house to point out the nature of the walls, floors and all the walls that separate the interior from the outside. Estimate their thickness. Look for their thermal resistance (see table below). This data will probably confirm a fact you know: your house is badly insulated. But above all they will allow you to decide, wall by wall, which thickness of insulation to add to reach the recommendations of the thermal regulation.
Analyze the insulation of an existing building
Each material has different thermal characteristics. From the nature of the walls and their thickness, you can estimate what thermal insulation you have today.
You can calculate the thickness of insulation to add to benefit from a well insulated home.
Insulation: special cases
- An insulation interrupted by the presence of a frame is less effective than an insulator placed continuously. Take into account in your calculations: if the frame is wood, keep only 80% of the value R. If it is metal, remember only 50%.
- If you want to keep the charm of an exposed stone wall in one of your rooms, or the frame of the beams of the frame, you must place the insulation on the outside. But if this solution distorts your facade or the roof, you will have to make a trade-off between aesthetics and comfort…
How to insulate the attic?
It is through the roof and the attic that the losses are the most important: 25 to 30% of heat escape through an uninsulated roof.
The new thermal regulation recommends that the floor of the attic space has a thermal resistance of at least 4.5 m2.K / W. This performance can be achieved with 18 cm of glass wool, vegetable or animal wool conditioned mattress, or 19 cm of rock wool or 27 cm of loose wool.
In the case of converted attics, the floor does not need to be isolated. On the other hand, the roof must be. Whether indoor or outdoor, RT 2012 recommends that the roof has a thermal resistance of 4 m2.K / W. Considering that the cover provides almost no heat resistance, to achieve this result, you must put 17 cm of rock wool or 16 cm of glass wool, vegetable or animal wool.
Low floor: solution for good insulation
No less than 7 to 10% of heat losses are found at the low floor.
The RT recommends reaching a thermal resistance of 2.3 m2.K / W when the floor is outside or parking and 2 m2.K / W when overlooking a crawl space or unheated room, such as a basement or partially buried basement.
In the latter case, this performance can be exceeded with 8 cm of extruded polystyrene, 9 cm of expanded polystyrene, or only 7 cm of polyurethane foam.
What tax credit rate for insulation?
If you decide to improve the thermal insulation of your home, you can benefit under certain conditions of a tax credit on insulation and its installation accessories, provided that the implementation is carried out by a company (invoice in support).
To find out about the various helpers to which you would be entitled and their conditions of implementation, visit the site renovation-invo-service.gouv.fr
11 powerful solutions to insulate well
Floor, roof, walls, there are a multitude of solutions to isolate all the walls of the house. But it's about finding the one that best suits the configuration of your home.
You must also make a choice between thermal insulation from the outside (ITE) and from the inside (ITI); each solution involving additional work. Finally, some systems are more difficult to implement or require specific equipment (spreading, self-supporting panels) that can be rented. Here are the most common solutions used to improve the insulation of an existing home.
Under crawling insulation
This solution involves installing one or two layers of insulation between the rafters or the purlins of the frame and then covering the set of drywall to paint (type BA10 or BA13) or paneling fixed on metal rails. When the roof does not go down to the floor, it is also necessary to isolate the vertical masonry.
The principle of sarking is to put on the rafters of the frame a decking forming inclined floor, then the rigid insulation panels (type polystyrene). A counter-bedding is then fixed in the rafters through the insulation. Battles and tiles then complete the cover.
Exterior insulation under plaster
The blocks of rigid polystyrene insulation are glued or pegged on the facade, which absorbs small irregularities. They are then covered by a fiberglass or metal mesh embedded in several layers of undercoated. The finish is a thick plastic coating, a fine aggregate coating or a mineral paint.
The panels are placed directly on the purlins to provide the functions of interior ceiling, insulation, roof ventilation and roof support. Adapted to traditional frames, this technique accepts all finishes. The implementation requires suitable lifting gear.
The sandwich panels are composed of an insulating type of glass wool or expanded polystyrene, associated with a plasterboard. The sandwich panels are 1.20 m wide and can be up to 3 m high, making it possible to coat the walls from floor to ceiling (glued down).
A metal frame attached to the floor and ceiling serves as support for vertical uprights. In the thickness slips the insulation, all being closed by plasterboard or paneling. If the walls are degraded, out of plumb or very high, this solution is preferable to the choice of sandwich panels.
In the interior, the insulation can be pressed against the wall and concealed behind a masonry counter-partition (plaster tile, cellular concrete or plaster brick) with a thickness of 5 or 7 cm. This solution provides thermal inertia, offers good acoustic insulation and allows the attachment of heavy loads.
Insulation by blowing or expanding
The floor of the uninhabited attic must be isolated. If the attic is not very accessible, you can apply loose insulation by blow molding or manual spreading. If the floor is regular (concrete, wood) the simplest is to unroll mattresses of insulation, in one or two layers on the entire surface.
If the ground floor is on a basement, you can insulate your floor by its underside. The principle is to achieve a ceiling reported: the metal frame is mounted on the ceiling every 60 cm to support the insulation blanket. Plasterboard is then simply screwed onto the rails.
Extruded polystyrene panels are placed on the ground and then embedded in a screed. The dry screed solution avoids this last step. The panels of reinforced plaster fit into each other. To increase the thermal resistance, they can be placed on an insulating underlay of wood fiber.
When building a low floor, molded slabs made of polystyrene can be installed between the beams. A cover tab avoids any thermal bridge. A slab of reinforced concrete is then poured. This system creates an effective insulating floor between the ground floor and an unheated room.