Lay out the attic: the 9 questions to ask


Lay out the attic: the 9 questions to ask


Lay out his atticit is the ideal solution for who wants earn square meters and have a new, pleasant living space. However, this renovation project is not easy and brings many issues that must be answered before starting work. Here are the good questions to ask yourself to complete your project.

Investing the attic allows to expand your home without having to move, and brings an undeniable added value to real estate. This requires however good preparation, because it is a question of modifying a place so far unexploited. It is therefore necessary to make sure the space lends itself, not to grill the steps and finally to study well its destination.

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1. Are my attics usable?

All attics can not be arranged. To find out if yours is "habitable", first inspect the framework, which can take two forms. Traditional - composed of farms of important sections, spaced and connected by breakdowns - its development will be realized without great difficulty. Industrial, either with wooden or metal trusses, a transformation is necessary to clear the space. Also note that to be exploitable, a ceiling height of 1.80 m is recommended, and a roof slope of more than 30%. It is considered that if these criteria are not met, or if the frame clutters the space, the roofs are lost. In the event that a simple layout of the frame is not possible, the project should not be abandoned, but we must consider more "heavy" work such as elevation or a change of slope.

In this sometimes atypical space, some planning tips can take advantage of every corner.


2. Is my roof in good condition?

Before thinking about the layout, always check the general condition of the frame. If it is wood, it is important to track down its weaknesses, the presence of insects, fungi, etc. And, if necessary, treat it before starting work. The roof must also be the subject of your attention. Have a roofer check for possible leaks, for example from displaced or damaged tiles, but also all the singular points (ornaments, valleys, aberrations ...).

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Insulation is one of the keys to successful landscaping. It allows to create optimal conditions of comfort.


3. How to isolate this new living space?

30 to 40% of the heat escapes through the roof, under which the temperature can reach 70 ° C. This is to say how good a thermal insulation is essential. To avoid being subject to significant temperature differences in summer as well as in winter, two insulation solutions are possible: from the inside or the outside. The first is the simplest and the least expensive. An insulator plate or roll is placed between the rafters or even between the purlins, and it is associated with a vapor barrier to prevent condensation and improve the airtightness. "In buildings with insulation from the inside, rock wool contributes to interior comfort, explains Amélie Piemontesi, communications specialist Rockwool. It slows the arrival of the heat wave, stores it during the day, which decreases its diffusion in the indoor air. " The disadvantage is the loss of living space.

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Insulating his house in rock wool ensures thermal comfort in summer and winter, good indoor air quality and incomparable fire resistance.


In Isover, a brand new glass wool has just been created. Cream-colored, based on a 100% biobased binder, it offers better laying comfort, improved thermal and acoustic performance, consistent quality and a better environmental balance. "For now, the new glass wool is available in the range IBR for the insulation of the attic and ceilings, but the entire range will be replaced in the coming months ", says Dominica Lizarazu, Marketing Director ofIsover.

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For comfort in all seasons and to save energy, it is essential to implement a high performance thermal insulation.


Exterior insulation will be reserved for heavy renovation or new construction due to implementation and higher cost. Its advantages are however significant: excellent insulation, a preserved surface and no work in housing, since everything is done from the roof.

4. What does the law say?

If the layout is less than 40 m2, a declaration of work is required. A prior declaration is also required for the installation of a skylight or window, the modification of the frame or roof. For an area greater than 40 m2, a building permit is required. The call to an architect is asked if the total living space after works is greater than 150 m2. Finally, the authorization of the Architects of the buildings of France is necessary if your house is located in a perimeter of 500 m around a historical monument.

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5. How to connect the attic to the rest of the house?

Access to the created floor must be thought out before starting work, but the boring of the hopper can only be done once the attic is done. There are many models of stairs corresponding to different configurations: straight, rotating, helical ...

The passage between this room and its dressing is facilitated by the sliding frame of this double door.

Edac / Deya

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6. How to heat the space?

For heating, the ideal is to connect to the existing central system, or to install electric convectors, choosing high-performance models such as radiators with inertia or with soft heat.

7. How are partitions created?

Cloison is an important step. The most suitable solution is to choose plasterboards, which are easily installed on a metal frame. Fermacell offers different products such as Greenline a plaque that neutralizes harmful substances in the ambient air, or Fermalight, whose dimensions (900 mm x 1,200 mm) facilitate installation. Knauf has also developed a whole range of partitions, acoustic, water-repellent, adapted to the needs of each one. In plasterboard, the novelty is named Live In. This new high hardness plate - more resistant to impact - is developed as standard or water repellent for wet rooms. It supports from 20 to 60 kg per fixing point, and allows to hang various elements, like furniture, shelves, mirrors ... Already commercialized, the plasterboard Ikebana, proposed by Placo in 42 colors and 18 patterns, create walls to the map: no need to paint the walls or cover them with wallpaper once they are installed!

easy to handle and transport, this plasterboard is perfect for attics. Waterproof, it also finds its place in the water. Easyplac.


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8. How to illuminate the attic?

The issue of bringing in natural light is crucial. The roof window provides up to 40% more light compared to a traditional skylight. Available in all formats, it goes from the simplest model to the one connected to the smartphone, with noise-canceling glass, self-cleaning, etc. The new finish WhiteFinish for all models Velux responds to a market demand. Present in 85% of the attic, this white hue with natural rendering increases the impression of space, and makes disappear the carpentry. Whatever your choice, consider complying with the legislation: a minimum height of 90 cm from the ground, and a distance from the vicinity of 1.90 m in the right view and 0.60 m in oblique view.

The new roof windows made of natural wood covered with a thin layer of white paint give a more contemporary look to your interior. While noticing the roughness of the wood, they offer more light and optimize the feeling of space.


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9. What is the cost of the operation?

It will cost you from 400 to 1,000 euros per m2. The difference is justified by the level of services provided by specialized companies, which range from rough landscaping (framework, floor, roof windows, staircase) to the turnkey formula, decoration and finishes included. As a general rule, the specialists consider that below 40 m2, the development of the attic is too expensive and not profitable enough.

Whatever the destination of the space, it is important to pay particular attention to the ventilation of the bathroom or any other room in your attic.


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Tools to help you

If you want support to prepare your development project, go to

This site created by Velux answer all your questions. "He gives step-by-step advice, provides information on legislation, financial aid, offers the connection with architects and professionals, says Thomas Berge, digital project manager. Moreover, it contains a simulator to estimate the habitable space which one will be able to have by arranging its roof spaces. Coming soon will be proposed a virtual reality application on smartphone, which will better realize the various possibilities to illuminate his attic "