Garage Conversion Insulation - what are the types and the methods.
Nearly all compliant garage conversion will require an upgrade of the walls, floor and
roof by installing new or extra thermal insulation. Under the Building Regulations garage conversions have to meet
modern day U values or thermal performance as for any new build works but there is a slightly lower acceptability
level threshold for conversion works if obtaining the required U value is costly or impractical.
Most house extension designers and architects have their own preferred methods and insulation materials for each
building element to be upgraded. Here is an overview of the general easily purchased insulation materials you can
GARAGE FLOOR THERMAL UPGRADE:- EPS (expanded polystyrene usually grade SD - a bit more dense). Celotex is an
alternative that is more thermally efficient than EPS which can be applied in thinner layers for the same thermal
efficiency. Kingspan make a variety of flooring insulation boards usually pink or light blue in colour.
GARAGE WALL THERMAL UPGRADE:- Form a 80mm cavity by using lightweight inner skin of blocks and fill cavity with
‘Dritherm 32’ cavity wall insulation batts. Infill between new stud frame inner skin walling with fibreglass or
mineral wool insulation. Stiffer boarding or batts is usually preferable to loose laid quilt stuffed into position.
Measures to be taken to prevent insulation falling into cavity created. Dry line with composite insulated
plasterboard fixed to existing wall with plaster dabs. This can be resisted by the Council for exposed externally
weathered walls as it dos not prevent ingress of damp.
GARAGE ROOF THERMAL UPGRADE:- Flat roofs often need to be enhanced externally with a new warm deck insulation
system. ‘Celotex Temp Check’ is one such system (there are many). Placing fibreglass or mineral wool between the
existing flat roof joists is another option but as this becomes a cold deck roof further additional external cross
venting will be require to remove moisture laden air that can be difficult to incorporate. Garage pitched roofs can
be improved with usual mineral wool or fibreglass quilt. Cross venting of the roof void will be required but is
usually easier to achieve than for a cold deck flat roof.