How much loft insulation do I need?
The Energy Saving Trust recommends a total depth of 270 mm for mineral wool loft insulation. Many lofts have less, so topping up is a common job.
Working out how much
Measure the loft floor area. Check the coverage printed on the rolls you’re buying, because it varies by product and thickness, then divide the area by the coverage per roll and round up.
How it’s usually laid
A first layer goes between the joists, then a second layer across them to reach the full depth. If you need to store things or walk in the loft, raise the floor on loft legs so the insulation isn’t squashed.
Also worth ordering
- Loft legs and boards for storage areas
- Insulation for the loft hatch
- Gloves, mask and goggles for handling mineral wool
This is a general guide, not a specification. Your builder, architect, building control or the manufacturer will confirm exactly what your project needs.
Get it priced
Use the insulation calculator, then send your list for a delivered price.