Please tell me the correct PVA for flooring? Timber flooring joists and Spruce ply going down.

FrankFalcon

Hi all

We are having our garage converted to a habitable room.  Planning has been approved etc.  All the brickwork has been done etc.  Our joiner was due to do the stud walling and the new floor joists in 3 weeks but the job he's on has stopped.  Therefore, he can jump on our job at short notice.  He gave me a huge list of things (4 x 2 timbers, 3 x 2 Timbers, insulation etc) the other week and lucky for me I got it all straight away.  However, on that list he gave me are the words 'Correct PVA for flooring'.  Taking into account this will be spruce ply (Travis Perkins) going down onto 4 x 2 flooring joists can somebody please tell me ASAP what product I need to buy?
Cheers all

Bendy_House

Eek, I don't know, but Travis should!

I suspect 'waterproof', for one. 'D4' stuff?

Ply for the floor? Does it have T&G edges? Why not the usual chipboard, I wonder?

fenwick458

Polyurethane D4 glue is what you use when you are installing new chipboard flooring
PVA is what some people do use to cure creaking chipboard flooring if the correct glue wasn't used when fitting, or if it was poorly fitted to start with (water down PVA and brush into the joints)

Bendy_House

fenwick458 said:

Polyurethane D4 glue is what you use when you are installing new chipboard flooring
PVA is what some people do use to cure creaking chipboard flooring if the correct glue wasn't used when fitting, or if it was poorly fitted to start with (water down PVA and brush into the joints)

That is what our builder used, right enough. It 'foams' slightly, so fills any gaps. The excess is easy to scrape off flush with the floor surface once cured.

Annoying that Frank's joiner said 'PVA'; do they REALLY want this, or is it a generic term for 'wood glue'?

Still confused by the choice of ply, tho'?

fenwick458

yes I'm confused by the ply too, the recent sheets of ply I have had are not flat (they are normally warped and bent) and they are bloody expensive now, seems a poor choice tbh. 
I hate chipboard too and think solid T&G floorboards are far superior over the 20 year span, but nobody seems interested in thinking that far ahead and always go with the cheapest chipboard rubbish and not think of the future.
the last time I looked at prices for T&G floorboard was a while ago and it was not more than 25% on top of chipboard so I appreciate somebody will probably point out that the price has quadrupled and they cost as much as the rest of the house put together but whatever...

Gavin83

What’s wrong with plywood for subfloors? I’d choose it over chipboard every time. Chipboard is rubbish and I certainly wouldn’t use it in my house.

I’m confused by the glue though. You don’t really need glue for plywood as long as you use a decent amount of screws and make sure they’re the correct type.

I do agree the general quality of plywood appears to be getting worse though.

Bendy_House

Our builder used 22mm chipboard. Solid as a solid thing. Glued T&Gs.

Grenage

Ply is obviously a superior product.  Chipboard is used because it is 'good enough'.  Unless it gets wet I don't imagine you'd ever know the difference.

I would use a glue designed for T&G,  but I'm not a tradesmen so I'd be playing it safe.

Bendy_House

Grenage said:

Ply is obviously a superior product.  Chipboard is used because it is 'good enough'.  Unless it gets wet I don't imagine you'd ever know the difference.

I would use a glue designed for T&G,  but I'm not a tradesmen so I'd be playing it safe.

Do you get ply designed for floors - T&G edges?

Grenage

You can indeed, although I've used square-edged with noggins in the past.  That's my preference.

Gavin83

If I was building a subfloor I too would use square-edged ply with noggins on the joins. It's what I've done in my house and the floor is rock solid. You can get T&G ply but it's a lot harder to find and I expect more expensive. Screwed down square edged ply is obviously far easier to pull up should you need to get to the electrics/plumbing underneath.

We had chipboard flooring. Along with the common squeaks we had several areas where it had completely cracked or was breaking up plus several areas that had sagged between joists. A few bits had obviously got wet at some point too which didn't help. Appreciate ply isn't perfect but I wouldn't personally use chipboard again.