In the sample plans which come with The Complete Self Build Garden Room Guide, we suggest you use a warm roof build-up for your garden room. This system has become very popular, not only in garden room design but in the construction industry as a whole. It’s popular because the roof space does not need to be ventilated in the way a cold roof build-up does.
With a warm roof build-up, you position a sandwich of roof decking and rigid insulation on top of your rafters.
Depending on the thickness of the insulation you choose this build-up could be quite a thickness. You also don’t want to damage your insulation or its performance when fixing the roof build-up into the rafters. There is also a risk that wind could get under the roof deck, with it sitting on top of the rafters, so you need a really secure finish.
Luckily there are special fixings available that can be driven through the roof decks and insulation into the rafters. These fixings normally have a twisted shaft which means they offer increased fixing strength, check them out.