Filling the gaps in floorboards event though we use plywood?

[Marjo]

Hi there

Thank you for taking the time to read and answer.

We are changing the flooring downstairs and the floorboards have many gaps.
The house hadn't been cared for a while before us.

We will use plywood underlay but should we fill the gaps between the floorboards before?

On one hand the house is pretty drafty and that would help to feel more comfortable, on the other hand we had issue with dry rot in the crawl space (oh sweet memory) so we want to keep some sprt of ventilation in imder there.

And while we're here, what product would you recommend? Knowing that we're not really good at DIY (but working on it) and some gaps are large (>1cm).

 

[robinbanks]

I'd be insulating between the joists, breather membrane under.. But if you're rating yourself as a DIY newbie that would be a lot to take on

 

[dazlight]

I’d just go 9mm plywood over the top