Conversion of a Garage into a Habitable Room
The conversion of an attached garage into a living space is treated as a
change of use of part of the building. An application for approval under
the Building Regulations must be made before you start the work.
The following is not an exhaustive checklist but must be considered when
thinking of converting a garage into a living space. If in doubt please
contact your Building Control Officer.
1. Foundations should be provided to carry any additional masonry
loads, such as a new inner leaf to external walls or the garage door in
fill.
2. If accessed via another room and not directly off a hallway the new
room should be provided with a window suitable for escape purposes.
The opening part of the window should have an area of at least 0.33m2
and measure at least 450mm in either direction. The cill height should
be no more than 1100mm above floor level.
3. If the property has no mains operated smoke alarms, it is a
requirement to install a mains operated smoke alarms to each storey of
the dwelling within 7.5m of habitable rooms.
4. External walls are required to be weather resistant. Single leaf walls
can be treated with a certificated product to achieve this. The
provision of an inner leaf to create a cavity wall will achieve weather
resistance but consideration should be given to installing a DPC tray at
the base of the wall.
5. The floor of the new room should be water-resistant and a DPM
should be installed under the new floor make up.
6. The new room should be insulated to achieve reasonable standards.
All elements should be insulated to achieve the following (Please
contact your Building Control Officer to confirm your construction
proposals).
Roof
0.16w/m2k
Exposed roofs
0.25 w/m2k (provide ventilation)
Exposed walls
Replacement 0.35 w/m2k
Renovation 0.55w/m2k
Floor
0.25 w/m2k
Windows
2.2 w/m2k.
7. The new room should have an opening window or door with an area
equivalent to 1/20th floor area or 1/10th if it opens through an angle of
less than 30°. Trickle ventilators should be fitted to windows to
provide background ventilation.
8. Shower rooms, WC’s, Kitchens and Utility rooms will all require
mechanical ventilation.