Floor insulation

[seanpk]

1930s house, original 25nom t&g on 6x2s, 3ft void down to dirt
The boards are in excellent nick so are to be sanded
It's just possible to crawl under the floor so am proposing to fit 50mm Celotex (excess from a previous job) between the joists for insulation - currently a cold floor

General observations?
Should I push the Celotex up to touch the boards or leave a gap?
Condensation issues?

Cheers, S

 

[freddiemercurystwin]

Tight up against the boards, secure with nails or battens, squeeze expanding foam into any gaps. We assume the under void ventilation is adequate.