levelling bathroom floor for vinyl flooring

[david_uk]

Hi all, I've read the sticky on this, but wanted to ask some questions.

Our bathroom floor is chipboard, but has a deffinite slant. Possibly 15mm over 1.7M. I'm renewing the entire bathroom so want to take this opportunity to level the floor.

Firstly, I understand I have to nail plywood to the chipboard first, but how thick does the ply need to be please?

Secondly, do I lay the vinyl straight on top of the compound with no further preparation?

Lastly, do I have to use some propietary brand mentioned, or is any product suitable for use on wooden flooring that I can get from a local DIY shed or builders merchant (Travis/Jewson etc) going to suffice?

Thanks

 

[mattysupra]

over chipboard you need 4-6mm plywood, you wont get this compound from a shed, has to be fibre reinforced compound to, and 15mm is a bit deep really. Does the floor have to be level? The idea of compund is to take dips out the floor and make smooth, not relly to make level to a spirit level. If you want to make level to a spirit level then i need to advice a bit of a different way to do it. Or you might want to take the boards up and bolt new joists to the old ones making level?

 

[david_uk]

Hi, and thanks for the reply.

Just to give a little more info, the reason I'm having to renew the floor is the old shower leaked and water had run between the chipboard and the plywood base for the tiles. I haven't got all of the old floor up yet, but I'd say it was 10mm down one end over 1700mm (width of the room).

Does it have to be level? My wife asked me that as we are having a shower bath instead of a shower, and obviously the bath has adjustable legs and can be made level. The tiling above will then work out fairly well (I hope!). So not from that point of view. My concern is that the bath is quite pricey, and I don't want to see a gap between the floor and bath panel one end of the bath. I know I can run a bead of silicone along it, but it's still a big gap that will show - hence thinking it's a good idea to level the floor. Or make it slightly more level than it currently is

So is it possible to make it a bit more level with the compound, or any other ideas? I'm not sure I want to go down the route of bolting new joists to the old ones. I don't think I;I'd make a good job of that over the width of the floor. But if I did go down that route, any advice for type of bolt and spacing?

 

[mattysupra]

if you replacing the flooring then take it all up and replace with plywood instead (18-25mm depnding on joist spacing, but if taken up chipboard i would guess 18-22mm will be fine)
Now you have the flooring up i would make the joist level! you can do this by fitting new joists at the side ( but not needed unless you have bounce in subfloor) or you could work out that lets say the floor runs out 15 mm over 3meter. Go to to your local timber yard and get them to cut some timber , lets say for example 3m long with a cut from 0mm to 15mm so you end up with some timber in a triangle shape. fasten this to the top of your joists and then put your new floor on top.

 

[david_uk]

Thanks for all of the great advice and info - much appreciated!

It's a bit difficult to tell *exactly* how uneven the floor is at the moment because there is some swollen chipboard down still. Wife won't let me remove it as she doesn't want to be without the loo for longer than necessary. Waiting for the bath and lino to arrive before I can take it up.

It actually seems to vary, with the corner of the room lowest at one end. However, this will be buried under the far corner of the bath so I'm not concerned about that. The actual bit where the bath panel will run, and the only bit you will be able to see a differnce in level seems to be OK with less than 10mm over 1.7M. I think I'm inclined to fit the new floor and see what it looks like.

TBH, if it's not that big a gap I might be inclined to go with mounting the bath with a difference of a few mm one end and hide it under the silicone sealant and jiggle the bath panel a bit.
Thanks again!