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Roofing: what to know before doing any work

Roofing: what to know before doing any work

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The roofing is the fifth facade of the building. It protects, emphasizes the architecture of the house but can also be energy-producing! Also, the roof of the house can not be chosen quickly. And here are 10 questions to ask you for choose your roof.

Can not neglect the roof. From an aesthetic point of view, the choice of roof can meet the requirements of a town hall but also its geographical area. From an environmental point of view, the roof reduces energy costs thanks to good insulation ... As you can see, choosing your roof is the subject of a lot of thought. Do not forget any point with this little recap of questions to ask yourself before starting your work.

1. Is there an ideal roof?

Let's put aside the aesthetic aspect. From an energy point of view, performance is where you do not expect it. According to the Promotoit association, it appears that the ideal house, the one that limits energy leakage as much as possible, has a sloping roof whose attic are converted. The saving made, compared to a house whose attic is not converted, is to 25 %. It's not nothing.

And if one is interested in the ecological impact, untreated wood shingles, natural slate and terracotta tile are recommended (according to the Dutch Institute of Biology and Construction Ecology, on www.nibe.org). Concrete tiles and metal bins, they, have an acceptable ecobalance, which is not the case of bituminous shingles, to be avoided from this point of view. For flat roofs, the Nibe classification recommends EPDM waterproofing membranes - a synthetic elastomer that resembles rubber - rather than bitumen or PVC or polyethylene type polymer films. Vegetable roofs, rather than pebbles, protect them.

See also> Roofing: choosing the right tile

2. Can we choose the roof cover?

In theory, everyone is free to "style" his house as he sees fit, but in practice there are constraints. The first is regulatory: we know that near a monument or in a classified regional park, we do not do what we want. A town hall may well require some type of cover, but also a shape, dimensions and / or color. The second constraint is technical: all coatings are not suitable for all roofs, but must be selected according to the slope and the geographical area (exposure to wind, snow, etc.). The third constraint is budgetary : A large-molded (that is, large format) large-tile tile cover necessarily costs less than traditional flat tiles. In the first case, 10 to 14 tiles per m2 suffice (65 to 75 € per m2), while it sometimes takes 60 in the second case (80 to 130 € per m2)! And more tiles per square meter, it is also heavier for the frame, which must be adapted.

Read also> A perfect roof

3. What other materials for his roof?

74% of houses are covered by terracotta tiles*, which leaves little room for other materials. It is true that for more than 2,000 years, the solution has had time to prove itself: the tile multiplies shades and formats, imitates slate, lauze, etc. But there are other options. Unless your future home provides a flat roof protected by a bitumen, elastomer or polymer, its cover can, if you live in Brittany or the north of France, be dressed with natural slates or fiberglass. cement. There are also concrete tiles (Monier) and bituminous shingles : come from the USA, these are less expensive than the tile, but hardly used in France, if not on additional buildings (garden shelters ...). Little used but home, wooden shingles are a priori intended for homes in mountainous regions. Larch, acacia or chestnut sawn or split, they are ecological, without treatment, but rather for roofs away from moisture. Ambiance Bois offers sawed larch shingles and announces lifespans of 30, 40 and even 50 years. If zinc also exists in shingles (Rheinzink), it is rather in the form of bins, in other words plates, that it is exploited in France, covering roofs original, flat or rounded. Maintenance-free and durable, it remains quite expensive.

Roofing what you need to know

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4. Old tiles on the roof of a new house, is it possible?

Yes, but it requires the use of a builder using old materials : it's rare, but it exists (Serge Gautier for example). Otherwise, we choose new tiles imitating the old models: these flat tiles or channel (never interlocking) are manufactured industrially or semi-industrial with dimensions, shades and irregular surfaces. All the manufacturers propose ("Restoration 16 x 27" or "Canal Réabilis" of Imerys, "Gayane" of Koramic, "Grand Cru" of Terreal ...), but it is more expensive (to count 70 to 90 euros the m2 for channel tiles and 80 to 130 euros for flat tiles, depending on the format).

5. A maintenance-free roof cover, does it exist?

Do not dream. With the exception of zinc roofing (rigid, large format and therefore not very sensitive to wind problems), the roof is on the front line in case of bad weather and it can happen that a strong wind, especially s it is associated with rain or snow, moves some tiles or other roofing element. And when it is not the wind, it is moisture that makes its own, promoting the development of moss, upsetting the evacuation of rainwater and causing infiltration. That's why you have to keep an eye on your roof and, after every winter or bad weather, look up and look at the roof: would a tile have moved, the ridge is in place, the gutters are- they clogged?

6. A roof to protect against storms?

More and more unpredictable and capricious, the wind often becomes storm, and not only in the areas usually exposed. In these, the regulation provides for additional protections (tile hooks and under-roof screen). On the other hand, in places considered calm, no regulation does not apply apart from hanging one tile out of five. If, in the opinion of a manufacturer of hooks (Dimos), the hanging of all tiles is justified only in risk areas (as the regulation provides), on the other hand, the installation of a under-roofing screen is unanimous, whether or not the house is in an exposed area. For a modest additional cost (5 to 7 euros per m2), this flexible film protects the insulation from infiltration of water, snow and dust, and reduces the wind uplift of the roofing elements. In addition, when the cover is accidentally damaged, the screen momentarily provides protection against water infiltration. But, be careful, it does not guarantee sealing!

Roofing what you need to know

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Read also> What to do in case of water damage?

7. What is the best roof insulation?

Most often, roofs of new homes are insulated from the inside. When the attic is not built, the insulation (mineral wool) is unwound or blown on the floor of the attic. When the attic is converted, it is almost always placed under the crawling roof, in two layers crossed, hidden behind a plasterboard. However, in the case of converted attics, the isolation from the outside with monobloc caissons (placed on the breakdowns of the frame) has advantages: it does not diminish the living space, it is continuous (deletion). thermal bridges) and allows a quick installation of the cover. In addition, depending on the interior décor (paneling, shutters), there are no finishes to be expected: in one operation (and with the intervention of a single profession), the attic, isolated, are ready to be covered, while inside, the crawlers are dressed and finished. Extra cost: approximately 7% compared to a traditional roof, but with the guarantee of a fast and perfect insulation.

8. How to avoid heat under the roof?

It is when the sun is at its zenith that it enters, through the roof windows, into the attic and often very well insulated: the heat is then trapped inside. The only way to evacuate, without air conditioning, is to create a good draft, effective when it is colder outside than in ... This is not always the case. To prevent the heat from invading the attic, it is important to choose the glazing of its roof windows, to keep them closed and to block solar radiation by equipping them with motorized external shutters, if possible automated ("Velux Active "from Velux). Note: Thanks to its reflective surface, a metallized under-roof screen is able to return about two-thirds of the heat absorbed, which reduces the heat transmission through the roof and therefore the interior temperature of the attic.

9. Roof: with or without solar panels?

Thermal regulation (RT 2012) requires at least renewable energy in new homes: pellet stove, heat pump, etc. But if you choose a conventional heating mode (gas condensing boiler), the solar thermal (hot water production) or photovoltaic (electricity production) can be the solution, on the roof or ... elsewhere! Solar thermal panels and photovoltaic can be placed on an awning and act as a sunshade, or vertically as a railing. If they are laid on the roof, solar panels (thermal) can be in the format of roof windows (Fakro, Roto Frank, Velux) or tiles (thermal or photovoltaic) for a perfect integration.

choose your roof

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10. And why not a garden on the roof?

A vegetated cover is installed on a roof-terrace, previously sealed (Soprema), or on a sloping roof if the system allows it. This is particularly the case of "Verdura" (Eternit), suitable for roofs with slopes between 9 and 60%. The waterproofing is achieved with profiled plates fixed to the frame, on which are placed precultivated bins (and with water reserve) which cling to each other by interlocking. It only remains to let grow, still planning some watering, at least the first year.