Draughty floor. Do we need plywood under underlay and laminate?

rosie383

We currently have floorboards throughout our 1930s house. There is a cavity floor underneath and you could feel the cold air coming up from underneath all winter. Some of the ground floor will have ply then tiles put down to link with new extension which will be having under floor heating. However, the living room and part of the hall is where we aren't sure what to do.

We have been advised that only marine ply would be suitable to put down but it costs about £49 per sheet. We know that it is the only sensible option for underneath the tiles, but what about under the laminate which we are planning on for the hall and living room?

Will underlay (the green boards) plus laminate (got quick step) be enough to stop the draughts? We got a whole new CH system and don't want to be losing heat if we can help it.

phil24_7

Underlay and and laminate will stop short of the wall/skirting so will stop the vast majority of draughts. How the detailing is done around the edge will determine whether you stop them all.

I would remove skirting and reinstall on top of the flooring and seal the top and bottom edge of the skirting (seal in ALL rooms) as this will stop them. If you can't/don't want to remove the skirting then fit an edge bead/trim/quadrant by sealing both edges.

Choose a sealant that remains elastic so that it doesn't impede the ability of the flooring to expand and contract.

Whilst you are looking at draught proofing, seal all window and door frames, inside and out, and check your window and door seals. Repair/replace where necessary.

After that you are left with the ever harder ways to stop draughts but that should cure most!

rosie383

Thanks Phil.
Windows and doors are all fairly new and chimneys are boarded up so they aren't a problem for draughts. It was the cavity under the ground floor which was the problem.
Thanks for confirming that we don't need the expense of plywood under the laminate.

greatgimpo

No, but you may need mould inhibitor once you're done.

rosie383

greatgimpo wrote: »

No, but you may need mould inhibitor once you're done.

First I've heard of mould inhibitor. Will have to do a bit of research on that. Thanks.

TheCyclingProgrammer

Our downstairs QuickStep has a vapour barrier, then fibreboard underlay then the laminate. The vapour barrier was lapped up the wall before the skirting was fixed over it. Skirting board caulked where it meets the wall. No drafts. You could tape the vapour layour to the wall with vapour tape for belt and braces but probably isn't necessary unless you're trying to get close to perfect air tightness. QuickStep do recommend you use their vapour barrier layer on downstairs floors.