Updated: Jan 27, 2019
A quarter of heat is lost through the roof in an uninstalled home. Insulating your loft, attic or flat roof is a simple and effective way to reduce heat loss and reduce your heating bills. Loft insulation is effective for at least 40 years and it should pay for itself many times over.
Here's what to consider before getting your loft insulated.
1. Storage space
If you plan to use the loft or attic for storage, you will want to lay boards over the joists. Unfortunately, if you only insulate between the joists before doing this, the insulation won't be thick enough.
To get enough insulation, you can raise the level of the floor so you can fit enough mineral wool beneath the new floor level. You can do this by fitting timber battens across the joists, or you can buy purpose-built plastic legs that fit on the joists and support the new floor. It’s important to leave a ventilated air gap between the insulation and the boards to prevent condensation on the underside of the boards.
The roof space will be warmer than with standard loft insulation, so you won’t need to worry so much about freezing tanks and pipes. You can board the floor for storage without having to raise it to create extra depth.
Insulating at rafter level is considerably more expensive than most standard loft insulation. As well as insulating the roof, you will have to insulate any gable walls, party walls and chimneys in the loft space. If you leave these un-insulated, then the heat will bypass your new insulation making it largely ineffective.