Before converting your lost attic space, it must be transformed into a habitable attic. This mainly consists in freeing up as much space as possible to install various equipment such as furniture, insulation, heating, ventilation, electricity, etc. To do this, we propose 4 solutions. Choose what suits you best.
Modification of the Frame
This is the most practical and least expensive method. The truss of the lost attic must be changed into a traditional truss to have a less cluttered space. Opt for this method if there is sufficient ceiling height. To modify a frame, remove the main triangulation and create partitions and flooring. The intervention of a carpenter is mandatory to avoid the risk of collapse of the roof. Among other things, you do not need a building permit to change a roof structure. However, you must declare to the tax authorities because your attic has become a living space.
If there is not enough height under the ceiling of your attic, opt for the elevation or the raising of the roof height. The purpose of this technique is to create an extra floor. This requires a height of 1.80 m on at least 2/3 of the space. Before proceeding with the elevation, you must ensure that the perimeter walls and foundations can support such work.
Then, you must know the materials that make up the load-bearing walls to verify their resistance. If the walls cannot support the elevation, they must be reinforced, or other walls or posts must be added.
The actual work begins with the dismantling of the old roof by removing the elements that constitute it or by hydraulic force. Then the tiles or slates must be recovered. Once the roof is raised, it is necessary to brace it by reinforcing the whole with props. Then, we finish by raising the walls.
You can opt for walls raised in original masonry, which is more practical and economical. Walls raised in formwork with reinforced concrete are also possible to ensure solidity. However, both options require the installation of thermal insulation in addition. In addition, you can use wood-frame walls to benefit from integrated insulation, but they are less aesthetically pleasing. Insulating the roof and the walls after an elevation is also essential. Expect to pay €1,500 for a structural upgrade and more than €2,200 for a complete upgrade.
Changing the Roof Pitch
Changing the slope is allowed if your roof has a low pitch or if it does not form an angle. To remedy this, a new roof structure must be installed and the roof completely renovated. To ensure that the slope of the roof is steeper, seek advice from roofing experts. On the budget side, expect to pay €60,000 for restructuring and up to €110,000 for a complete renovation.
This principle consists in lowering the ceiling of the first floor or the floor below. You need to leave 2.45 m of available height for a living room and 2.30 m for a bedroom. In addition, check that your floor can support the extra loads generated by the equipment and materials installed in your converted attic. It is recommended to resort to lowering the floor only if you have no other choice, for example, if your municipality forbids raising the roof according to the local urban plan.