Expanding foam around perimeter?

[rhysjc]

Hi all, in need of some advice!

I’ve taken up the old carpet and will be laying LVT after I’ve overboarded with some ply. My question is around what I should be doing around the edges of the floorboards where there’s a gap to the wall? When I removed the old skirting there was some sort of black fibre stuffed in the gap. I assume the idea is to stop drafts though this is upstairs so above a heated room, and maybe also to block some noise?

Should I be replacing this, and if so with what? I was thinking expanding foam but concerned that may stop the boards expanding?

 

[Wayners]

Foam is soft. Won't stop movement of boards

 

[rhysjc]

It does set pretty hard, maybe it’s soft enough to allow expansion still?

 

[drives]

You will be fine with expanding foam around perimeter, and then trimming it back. Whether this is more effective than what you have in situ, is possibly debatable. With the ply overboarding you are screwing it down at 150mm centres I'm guessing, so any expansion will be negligible anyway.

 

[rhysjc]

Thanks for that @drives . I ended up not putting anything in, but I'm going to be pouring some self leveller now so I'll be shooting some low expansion foam in anyway to create a dam. I'll cut it flush once it's cured so that should do the job. As you said, I got through just over 400 screws doing a 2.5x2.5m room, so that ply isn't going anywhere!

 

[opps]

Foam is soft. Won't stop movement of boards

I often use PV foam to strengthen scribed (skirting) corners in victorian houses. I became annoyed with the carpet fitters breaking caulk on the scribed corners. I drill a series of holes near the corner, then fill with expanding foam. To date, none of those joints have split when they use the carpet kicker.

My local pub, they have floor boards that are suspended by about 2". The manager complained about two particular boards that were dipping down where they meet the tiles at the edge of the bar when someone stood on them. I drilled a series of holes and squinted in lots of foam. That was 6 months ago. It is still holding up.

PU foam is a much underrated product. And yes, used inappropriately from time to time.