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House with converted or lost attic: 7 comparisons

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A house with convertible attic includes spaces under roof which can be transformed into habitable rooms. Conversely, the lost attic often have insufficient height, or are created by a type of frame, (farmhouse) which makes development difficult or even impossible. Both constructive methods have their advantages. Here are some arguments for choosing between one or the other solution when you do build a detached house.

House with convertible attic: a scalable house

A house with convertible attic space represents a fantastic opportunity to expand living space without having to increase the floor area of the House. By transforming these areas into additional bedrooms, office, playroom or leisure space, you significantly increase the functionality of your home without subsequently requiring a costly extension. Requiring the creation of a traditional frame, these living spaces under the roof can be fitted out during construction or used, in the meantime, as an attic or storage space. The house thus evolves according to the budget and needs, the finishing touches being able to be postponed until later, when the first child arrives, for example.

To go further, read our article “ Why build a scalable house in the South West? »

farmhouse frame and lost attic.
The farmhouse frame or industrial frame is made up of multiple wooden elements assembled by metal connectors. Economical and lightweight, it takes up a lot of space in the attic.

Lost attics or creeping insulation, what thermal performance?

New house attic: what insulation?

In lost attic,insulating in panels, in rolls or in bulk is placed, unrolled or blown onto the floor of the plancher high or on the joists and ceiling. Conversely, theinsulation of convertible attics follows the shape of the roof. The strips of insulation are inserted between the elements of the traditional frame, behind the plasterboard. We are talking about insulation under the roof.

Lost attics or creeping insulation which has the best summer comfort?

In summer, the rooms located under the roof are triple exposed to outside temperatures. First, heat rises and tends to accumulate on the upper floor. Then, the roof windows can promote the greenhouse effect. Finally, the materials of roofing heat up quickly in direct sunlight. These disadvantages will nevertheless be limited by very efficient insulation, automatic rolling shutters and a nocturnal overventilation. In terms of summer comfort, unused attics offer fewer constraints since they create an additional buffer space between the heat of the roof and the habitable space.

To go further read the article “ Building a bioclimatic house in Gironde: 11 tips for a cool house in summer ».

the lost attics protect the house well for a comfortable home.
In lost attics, the insulation in panels, rolls or in bulk is laid, unrolled or blown onto the floor of the upper floor or onto the joists and the ceiling.

House with convertible attic or lost attic, what winter comfort?

Since the thermic regulation 2012 and more the 2020 environmental regulations known as RE2020 who regularly individual house construction, the houses are very well insulated. The majority of heat loss in winter occurs through the roof, the insulation thicknesses are high and adapted to guarantee very low energy consumption, whatever the technique used. If not used, the convertible attic must be isolated from the rest of the home to avoid excessive energy consumption in winter. While waiting for their future habitation, we can thus place the insulation on the upper floor like the attic space.

The charm and aesthetics of houses with attics

This is a clear argument in favor of exposed frames and convertible attics. Indeed, insulation under the roof reveals the volumes and, depending on taste, allows you to play with the wood of the frame. Upstairs is the opportunity to benefit from attic rooms (bedrooms, office, bathroom) with undeniable charm, and beautiful height effects on the ground floor. THE single storey houses gain in volume, with high ceilings, see living rooms with cathedral ceilings. Serious assets for resale.

An attic room is charming and warm.
An attic room has an undeniable charm. Jonathan Borba on Unsplash.

Convertible attic, what additional cost in construction?

When choosing attics that can be converted into a new house, certain items are higher:

– Insulation under the ramp:

It is in fact more expensive than that of lost attics, because the implementation is longer and more demanding.

– Raise the roof for a house with a converted attic:

When the roof slope imposed by the Local town planning plan (PLU) is not sufficient to have convertible attics, it is sometimes necessary to raise the walls by a few centimeters which leads to additional costs in terms of materials (wood, bricks, etc.).

– Frame:

The traditional frame is more expensive than the truss option. However, this additional cost is not that high.

- Design :

The design is more advanced because it requires anticipating future developments. the location of the staircase and the hopper must be carefully studied. The same goes for the distribution of heating and cooling circuits and hot and cold water supplies.

– High floor:

This may or may not be carried out at the same time as construction to benefit from a accessible attic.

- Stairs :

The staircase can be built during construction or simply planned and built later when the budget allows.

To go further read our article “ Building in the Southwest: a two-storey or single-storey house? ».


House with convertible attic: long-term savings

Do build a house with convertible attic, it means anticipating future developments. A well-developed project with your builder houses SIC will save you money. In fact, the additional cost of constructing and fitting out the attic will be lower than creating an extension or raising the roof in the future. It is also a serious advantage for the resale of your property.

Passage of networks and maintenance of the house

Heating, ventilation, lighting, electricity, etc., all the circuits and networks in the house are easily hidden in the attic. Network cleaning or maintenance operations are thus made easier. These configurations thus offer the opportunity to more easily benefit from a duct heating which heats the house discreetly.

Building a convertible attic also depends on the slope of the roof.
Climatic zone roof slope by region in the South-West.

Attic and south-west roof slope

Standards and roof pitch in the South West

Roof slopes are dictated by the climate and the roofing materials used. THE steeply pitched roofs concern regions with high and regular rainfall.
La zone 1 is located less than 40 km from the coast and 200 meters above sea level.
La zone 2 is located between 20 and 40 km from the coast and at a height of between 200 and 500 meters above sea level. this concerns the entire coastline: Landes, Gironde, Charente.
La zone 3 is a maximum of 20 km from the coast and more than 500 m above sea level.

House with attic Pyrenees: volumes to exploit

In the South West, it is in the Pyrenees that PLUs impose the most steep roof slopes. This is due to the climate and the risk of snow. The slopes thus range from 45° to 60° which offers a largely habitable volume in the attic since a person can easily stand up.

South-West single-storey house: attic and low roof slope

In zone 1, but also in zone 2, that is to say if you build on the coast Atlantic, a ground floor house of average size, does not offer sufficient attic height to create habitable rooms. The frame with a truss is then more advantageous. However, it is possible to raise the walls a little, to create a mezzanine, habitable attic, or enjoy a new living room under the roof. It is thus an economical alternative to the construction of an upper floor, halfway between the single storey house and the house R+1.



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