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Under ceiling insulation

The development of the basement or garage to transform them into a living room is tempting, since it is the promise of a new living space without having to do real extension work. Nevertheless, and unless the premises are new and have been designed to be developed, this type of assignment requires significant work. Insulation, heating, upgrading, decoration: the steps to install a new room in the garage or basement are numerous and expensive.

Make an inventory

A garage, whether attached to the house or established in the basement, was not designed to become a habitable room. A number of constraints can make the assignment in place of life more or less difficult. We must also take into account the fact that we will lose a storage room (to begin with, the car) which will have to compensate the surface and the volume.

Ceiling height
The walls must also be controlled and the ceiling height compatible with the concept of living room. Legally and fiscally, we consider that a surface is habitable if the ceiling height is greater than or equal to 1.80 m. In practice, it must at least be at least 2.20 m. If the rooms were not originally designed to be habitable, it is likely that the ceiling is quite low. Two options are necessary then:

  • implement a room that requires little ceiling height (like a dressing room, a bathroom or a movie theater);
  • disburse the soil and rebuild a slab, a screed and lay a floor covering whose surface will be at least 2.20 m from the ceiling. This option may not be possible, and low ceiling height may be a constraint that you will have to deal with.

The ceiling height available should take into account the thickness of a possible ceiling insulation or, at least, a plasterboard doubling under frames.

Fluid passage
The pipelines and piping are often apparent in cellars and garages. It is not always necessary to move them, and it is possible to set up false ceiling solutions (if the height allows it) or formwork to hide them, while leaving them accessible. If the new room requires the disposal of wastewater, it must be ensured that the existing pipes can be connected. The challenge is (especially for basements) to have a sufficient height difference for the flow. In this case, the installation of a lift pump.

Water lifts
For the development of a garage in the basement, it will also be necessary to ensure that there is no seepage from the ground and into the walls (Cellars and garages are often in direct contact with the ground and are particularly subject to it). In an attached garage, it will be necessary to check that there is no hair lifts, this part of the construction may not have a stripe. In the case of a basement installation, provision must be made for check valve on the sewage pipe.

Hazardous Material
Banned for many years now, certain hazardous materials such as lead or theasbestos can still be found in garages and basements of old buildings. Asbestos may be present in putty glue or in welds, or in the cover of schedules prior to 1997. Many paintings before the 1950s are leaded and many water supply pipes are also made of lead. It is necessary to analyze samples and proceed to the eradication or the encapsulation of these materials in accordance with the standards and safety instructions in force.
Warning: Abstain from sawing, drilling, sanding or filing materials containing asbestos whose dust could be inhaled!

Priority works to build a garage

Thermal and acoustic insulation
It is very likely that the first works to be done (if the pipes, the ventilation and the electricity did not pose any major worry) have to do with theinsulation of the room:

  • thermal insulation of the floor, walls and ceiling or roof (adjoining part),
  • acoustic insulation, especially the ceiling for a basement, as poor soundproofing can be very damaging to the comfort of life in the rest of the house as in the new space.

Ventilation and natural lighting in the garage

Good thermal insulation passing through a very good airtightness, the air renewal a garage (especially if it is in the basement) converted into a living room is essential. A connection to the VMC (If the house has one) is essential, knowing that sometimes it is necessary to review the power of the group as a result of the increase in the volume to be treated. Failing this, provision must be made for extraction and specific air intakes. The enlargement or the drilling of windows will participate in the natural ventilation, but also in the illumination of the room. The installation of a skylights may be wise.

Administrative procedures to create a room in the basement

All works that increase the living space are a priori subject to various regulations. In condoit will necessarily require an agreement from the trustee before starting work.
In all cases, depending on the area concerned and the nature of the work, it is also possible that a prior declaration of work (for surfaces between 5 and 20 m²) or a request for building permit (for surfaces of more than 20 m² or more than 40 m2 in urban areas subject to PLU) in town hall. Depending on the work planned, it is possible that the issuance of the building permit is subject to the presence of an access or an opening (among others for security reasons). If the increase in living space increases the total area of ​​the dwelling to more than 150 m2, the use of an architect is necessary. Any increase in living space induces a increase in property taxation.

Document yourself to find inspiration

Once the actual development work done, we must now find inspiration for the decoration of the future room. In basements and garages, there are many options. As these spaces are often less luminous and open than the rest of the house, we will favor rooms that need the least direct natural lighting. Dressing room, bathroom, home cinema or even extra desk are classics.

On the same topic

  • DIY tips
    • Wall moisture problems: adapted treatments
    • Insulation of a garage door
  • Questions answers
    • How to build a garage built on a crawl space?
    • How to create a home theater room?
    • How to build a cellar?

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