The most traditional form of roof space (Loft) insulation is mineral wool matt. It is simply rolled out over the ceiling between and over the ceiling joists. This is the most common form and current building standards require a depth of around 250mm.
If you want to use your loft as a living space, or it is already being used as a living space, you can insulate your room-in-the-roof by insulating the roof itself rather than the loft floor. This is typically done by fixing rigid insulation boards between the roof rafters. Boards must be cut to the correct width so that they fit snugly between the rafters. They can then be covered by plasterboard. Rafters aren’t usually very deep, so to get the best performance you may have to insulate over them as well using insulated plasterboard. If there isn’t room to do this, make sure you use the highest performance insulation board.
Walls in the roof space and around dormer windows should also be insulated. This is typically done with rigid insulation boards.
In all cases adequate ventilation should be maintained to the rafters.
A flat roof should preferably be insulated from above. A layer of rigid insulation board can be added either on top of the roof’s weatherproof layer or directly on top of the timber roof surface. A new weatherproof layer is added on top of the insulation. This is best done when the roof covering needs replacing anyway. If your flat roof needs to be replaced anyway you must now insulate it to comply with building regulations.
It is possible to insulate a flat roof from underneath, but this can lead to condensation problems if not completed correctly.
Installing flat roof insulation could save you similar amounts on your heating bills to loft insulation. The savings will vary depending on how much of the property has a flat roof.
If you are looking for someone to insulate your roof, you will find installers listed in the National Insulation Association.
We can also provide you with recommendations for local reputable installers.