Insulating a loft that’s already boarded

Option 1: lift, insulate, raise

The boards come up, insulation goes in to full depth, and a raised floor goes back on legs above it. This gives the best result and keeps your storage. It is the most work, but the boards can sometimes be reused.

Option 2: insulate everything that isn’t boarded

Often only the middle of the loft is boarded. Topping up the rest to full depth and insulating the hatch may get you much of the benefit, while leaving the storage area as it is. Worth doing if you don’t want to disturb the boarded part.

Option 3: insulate the rafters

If the loft is used a lot, or for things that shouldn’t get cold, the roof slope can be insulated instead, usually with rigid boards. That makes the loft a warm space. It is a bigger job and needs careful thought about ventilation. See rigid boards.

What about blowing insulation under the boards?

Loose-fill insulation can sometimes be blown into the gaps under existing boards. It only works if the space under the boards is fully open and can be filled evenly, and the boards would still be sitting directly on the insulation. We can tell you whether it suits your loft.