Sealing plywood prior to LVT

[Perjorative]

We are currently renovating our house room by room and I'm going to be starting on a room that will be used as a home office. Initially it's going to be carpeted with a cheap end-of-roll that is currently sitting in the garage but, when funds allow (probably early next year), we want to get some LVT professionally installed (Karndean or similar)

It's not a particularly large room at 2.5m by 3.5m and, as with all the other rooms we've done, I'll be screwing down any loose/creaky floorboards and then laying 9mm ply over the floorboards, skirting boards will be replaced and be on top of the ply so I'd like to prep the floor in a way that the future LVT installers will be happy with.

I'm a competent woodworker and have no problem in profiling the ply to closely follow the walls/door opening. I've read the Karndean floor prep information and I'm willing to spend the extra on FG1 ply and follow the guidelines by screwing it down at 150mm centres/100mm at edges, avoiding joins that correspond with floorboard edges etc.

When I've put down ply in other rooms that have been carpeted, I've sealed the ply using a 60:40 mix of SBR:water to stop any accidental spillages (or puppy urine) soaking into the ply.

I don't want to cause any problems that would result in the ply needing to be removed & redone in order to lay LVT so wondered if sealing the ply in this way will cause any problems with the adhesives used for LVT?

Thanks

 

[Jon]

Have you considered just laying the carpet then when ready to lay your new floor put down the ply as you will then have a brand new floor to lay on?
I am not certain of the ply you are going to use as I live in New Zealand but one of the "local" guys should be along soon to steer you in the correct ply to use as there are plys and plys
Maybe Karndean recommend a type of ply to use?

 

[Perjorative]

Have you considered just laying the carpet then when ready to lay your new floor put down the ply as you will then have a brand new floor to lay on?
I am not certain of the ply you are going to use as I live in New Zealand but one of the "local" guys should be along soon to steer you in the correct ply to use as there are plys and plys
Maybe Karndean recommend a type of ply to use?

I want to get the skirting installed so the ply needs to go down first. I tend to remove skirting then wallpaper down to below the top of skirting level, then install the skirting so that it overlaps the paper - a bit of masking tape and caulk along the top of the skirting makes for a lovely clean join

There's also the question of cost, if the installers put down the ply, it'll be additional cost and it's something that I'm capable of doing

AFAIAA the FG1 plywood is correct for LVT - although I'm sure that someone will correct me if I'm wrong

 

[Jon]

Nah you dont have to pay someone to lay the ply after the skirting is installed as you said you are competent so you could still do it when you are ready
Here we never get jobs with the skirting boards off so we cut the underlayment into the skirting boards and around door frames neatly. Meant to leave a slight gap but nobody does
Also when your floor layers arrive are they going to expect the skirting off or are they going to fill around the edges with a silicone or similar?
Once again we cut the flooring tightly against all walls etc No gaps No get pay as people moan if there are gaps
So I wouldnt even think of doing it your way as you could run into trouble later having to put down new ply
Another thought if you seal the ply it will needed to be removed or covered over with a product like Feather Finish or similar as the glue for the Karndean needs something to dry into

 

[Perjorative]

Another thought if you seal the ply it will needed to be removed or covered over with a product like Feather Finish or similar as the glue for the Karndean needs something to dry into

That was the info I was after - thanks - I won't seal the ply then.

The other reason I want to get the ply down is that it's a ground floor room with a couple of old rugs on the floor and over the winter, when the wind was blowing directly towards the airbricks, we could feel cold draughts coming up through the floorboards. As the temporary carpet is only going to be down for about 12 months before being scrapped (or maybe used on the garage floor so when I'm under the car, I don't have to lie on concrete), I'm not going to bother with any underlay and rely on the ply to stop the drafts.

I don't know what the fitters will expect as the LVT is still about a year away - I could possibly buy 'el cheapo' brand MDF skirting and screw it to the walls as a temporary measure, then it would be simple to remove when we have the LVT fitted and I can fit the 'proper' skirting afterwards. That would give me plenty of time to profile new lengths of skirting on my router table (I could buy it but it's more satisfying making it yourself).

At the moment, the driver is to get the room into a warmer/more useable condition so my wife can use it as it appears that her 'temporarily working from home' situation is likely to become a more permanent arrangement.

 

[Jon]

Why not use real skirting screwed to the wall then just unscrew when ready?
Another thought how about a thick plastic or builders tar paper taped over the joins to protect the ply?
I am worried that your ply could get damaged from water spills, puppy etc
I dont lay carpet so dont know if that would be a good idea?
We dont use much ply here as most use 6m MDF with very little problems but I would be going with ply in your case as MDF needs to be covered with flooring straight away due to water and other damage as painters like to get more paint onto the floor than the walls
Where are the local guys as its a wonder nobody else as replied

 

[highup]

Because you're doing so such a nice job Jon.

 

[Perjorative]

Why not use real skirting screwed to the wall then just unscrew when ready?

Real skirting is what I'll be making - but I don't have time for that at the moment. I'll profile oak on my router table and oil it before the final fitting. I don't like screws when the wood is oiled as plugs never match the grain properly and I can always see them. For unpainted skirting I prefer to glue it in place.

Another thought how about a thick plastic or builders tar paper taped over the joins to protect the ply?

That's a good idea - I think I have a roll of thick plastic in the attic (if not I know where I can lay my hands on some for free), I could staple that down so it doesn't slide around under the carpet

 

[Jon]

I dont know if the plastic will cause the ply to "sweat" but highup will shoot that idea down in flames if it could cause problems
As I mentioned we would do things all different down here at the bottom of the world in NZ

 

[highup]

 

[highup]

It's hard to tell if plastic would be a bad idea. If it's temporary and the underside of your house has a good moisture barrier and ventilation on the ground it might be okay.
Moisture travels or seeks warmer dryer locations. If the moisture and humidity is high outside and under your house it wants to move inwards to equalize. In doing so at least in theory, the plastic will stop moisture from coming into the house. However it will stop the moisture directly at the underside of the plastic. There is a product with a brand name of Aquabar-B It's very good at stopping moisture but does have a very slight breathability to it. Basically it's a double sided craft paper with a very thin layer of a tar like material in the center. I've also heard it called 30-30-30 paper. It's commonly used as an underlayment prior to nailing down solid wood flooring. It's just unrolled and stapled down lightly.
If your main concern is puppy pee, there are carpet paddings that are pet proof, meaning they have a good moisture barrier or skin on top of the foam.

 

[Jon]

highup he mentioned that he already has the carpet in his first post which he is going to lay over the ply which is why I suggested laying the ply at a later date to prevent any damage as the Karndean could be 12 months be fore its laid

 

[Perjorative]

Thanks for all the advice folks - the new puppy isn't a forgone conclusion yet, my wife is talking about it but it may not come to anything this year (but I like to be prepared)

I have a friend who's a roofer and he's giving me some 'breather membrane' - he said it's waterproof but air permeable so should work fine as a temporary layer between carpet and ply

I need to put down something to flatten the floor. My worst case scenario is that the FG1 ply gets damaged and I have to replace some or all of it. The FG1 isn't that much more expensive than standard ply and I'm happy to offset that cost against putting down cheaper ply and then definitely having to replace it all with FG1