When insulating a pitched roof at rafter level there are a number of key design considerations which will affect the build-up of the roof and the choice of insulation. In this article, we explore some of the options available.
When we are talking about rafter level, we mean the timbers that support the pitched roof. Joists are the flat horizontal beams at ceiling level.
The main decision to make when insulating a pitched roof is if you are going to have a warm roof or a cold roof. This will depend on the construction of your roof, and if it is a refurbishment, or whether the roof tiles are going to be removed.
The main difference between the two is the location of the insulation.
- A warm roof is where the insulation is above and between the rafters (so the rafters are kept warm).
- A cold roof is where the insulation is between and below the rafters (and the rafters remain cold).
For a new build, or if a detached dwelling is being re-roofed, then there is scope to choose the build-up of roof that suits your purposes best. However, if the roof insulation is being added to an existing roof, for example as part of a loft conversion, then a cold roof is the most likely solution as you can’t insulate above the rafters.
