Fiberglass batts are the worst possible insulation to use in rafter bays because of all insulation types fiberglass is the most permeable to air.
Dormer attic insulation.
Knee walls are found in many older houses where the ceiling on the top floor is an attic or there is a dormer window.
Do dormer bungalows and houses with attics in the roof space need a different approach to insulation.
In an existing dormer or 1 5 storey home icynene spray foam insulation can be easily fitted to the difficult to insulate areas such as crawl spaces and closed sloping attic sections using our unique cannon tip application method and in areas totally inaccessible icynene can be injected through the plasterboard.
The depth of your rafter will determine what size of insulation should be used and in turn what size of plasterboard slab should be fitted to achieve current building regulations.
This method requires the use of 150mm thick insulation between the rafters and a 50mm air gap to prevent cold bridging occurring.
If interior air gets into the rafter bays the fiberglass batts do nothing to prevent the warm moist air from contacting the cold roof sheathing.
Dormer roofs are roofs that contain rooms and can present considerable challenges when it.
There are a number of options for insulating a new dormer roof.