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Can I roll out loft insulation over crawl boards?
Anonymous user 09/03/2026 - 8.03 AM
We just moved in, and the loft appears to have crawl boards over the joists. It might have insulation betwene the joists, hard to tell. There is loose insulation in the loft left over - can we just roll this out over the crawl boards to improve the insulation of the loft? Will this cause any damp/cold spots/other issues? We won't plan to store anything on top of the insulation where it is rolled out. Thanks.
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2 Answers
Robert wood
Rating: 5 out of 5
Hello. Yes you can put insulation on top of the crawl boards.
Answered22 January 2026
1
HomeRenoUK
No reviews yet
You can lay additional insulation over crawl boards, but it won’t be as effective.
Ideally, insulation should be installed between and across the joists to around 270–300mm depth.
If the loft already has boards installed, a common solution is to lift the boards, install additional insulation, then refit the boards on raised loft legs. This allows the insulation to reach the correct depth while still keeping a usable storage area.
As long as airflow is maintained at the eaves, adding insulation will not cause damp issues.
This is something we regularly come across when improving loft insulation in existing homes.
Answered9 March 2026
1