How much loft insulation do I need?
The short answer for mineral wool is around 270 mm. Here’s why that takes two layers.
| Recommended depth (mineral wool) | 270mm in total |
|---|---|
| Made up of | A layer between the joists plus a layer across them |
| Other materials | Depth depends on their thermal conductivity |
The depth
Around 270 mm of mineral wool is commonly recommended. Other materials can need slightly different depths.
Why two layers
Joists are about 100 mm deep. One layer fills between them; a second across the top covers the timber and makes up the rest.
Common questions
Can you measure my loft and quote?
Yes. The quote is free and in writing, with every part priced.
Full depth below. Room to store above. Get a price.
Tell us about your loft and we’ll quote the insulation, boarding and ladder in writing. Free, no obligation.