Getting plank subfloor flat

[rhysjc]

Hi everyone,

Looking to install click LVT in our upstairs bedrooms. I’m aware of the opinions on this but given kids/dog on the horizon we need something durable and the budget doesn’t stretch to a professional glue down install. I’m hoping getting the prep right means an install that will last.

With that in mind, I’ve ripped up the old carpet and underlay. The subfloor is original timber planks. Some of them are loose (one literally isn’t fixed at all!) so I’ll fix those back down to the joists with wood screws. Even still, there’s some significant high and low spots which I’ll need to sort.

My initial thinking is to overboard with 6mm ply. If that doesn’t do the job I could apply a thin layer of self leveller on top. Does this sound like a sensible plan? I’ve read about smoothing out with a floor levelling compound but all I can find is self leveller, which I believe you can’t feather out and needs to be done across the whole floor? Either way I’m not sure how I’d fill the gaps between the existing boards to stop this pouring through to the ceiling below! One concern is I’d be adding 9mm to the floor at a minimum!

 

[Tigercubrider]

My house has thresholds between rooms (oak or similar boards) so flooring height isn’t so much of an issue.
I laid the cheapest laminate in my bedroom at about £3.50 sq M years ago.
My boards have a really annoying groove between each board - they are T&G but there is enough gap to loose a pencil between them and I was concerned that a join might coincide with a gap.

I used a compressed board underlay that was soft enough to even out any height issues.it is also supposed to help with noise
There might be a way to lay underlay then thin ply?

Not an expert

 

[rhysjc]

Cheers for that.

The LVT has a built in underlay, needs to go direct on the subfloor. My boards aren’t T&G but the gaps aren’t actually too bad. I think just ply would be okay in terms of floor height, adding some SLC on top of that might cause a bit of an issue for a regular threshold bar. Worst case suppose I could increase the height of the hallway to match. It’s just as out of level, but will be carpeted.