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 choose from:-

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.