Ask a tradesperson

Hard Flooring

How to lay vinyl floor in bathroom with floorboards

Can a vinyl floor be layed on top of floorboards in a bathroom or does it require an underlay? What kind underlay an thickness would be required. What of the floorboards are even is an underlay still recommended or required?


Does it need to be any special type of plywood? When screwing it down what length screws should I use, how far apart should they be spaced and do you screw through floor board into joist or just the floor boards? Since the floor board are screwed to joist, it would be difficult to locate them plus not enough space as I could potentially hit the screws of the floorboards. The vinyl will be removed every year and replaced, so I don't need it for long term use but currently laying it directly on floorboards gives too much bounce and echo.

Also if laying plywood do i need to leave 6mm expansion gaps between the plwood and walls? How would I cover the gaps since vinyl will simply curve into the gap?

There is no skirting, wall tiles have been tiled all the way down to the floorboard on to a 5mm thick strip of wood. Basically there is a 5mm strip of wood around the edges of the room on the floor boards and the wall tiles have been tiled up to the strip of wood but the wood isn't flush with the tiles in some places it sticks out about 4mm. I'm thinking of getting a stanly knife and cutting the wood fluss. If I lay the ply do I now need to leave a gap between the ply and the strips of wood around the edges or is that not necessary. If I leave a gap then the vinyl wond sit flush to the edges. When I phoned a flooring merchant, he said I needed 9mm ply or is he just trying to sell me something that's going to cost more. Thanks for your help.

I've grid the boards with screws 150mm apart - its a lot of screws! It seems ok but I was just wondering whilst i understand glue used in exterior ply is water resistant the surface of the ply wood clear isnt water proof - it soaks up water. I know I'll be laying vinyl on top but I was just curious to make these ply boards waterproof/moisture resistant is there any kind of sealant that can be applied which wont adversly delaminate the plywood sheets?

When i've dropped water on the ply i've noticed it soakes up water. Does plywood need to be layed on a specific side? I bought two sheets on one sheet one of the sides appeard more smoother than the other. The other sheet I couldn't really tell the difference between the two surfaces?

Additional 2

Once again thanks for all your help. I'm just doing the finishing touches where I need to fasten a vinyl/carpet edging trim along the door. Unfortunately at the juncture between the vinyl and the carpet, the floor where the edging trim sits, there is gap between the floorboards so I'm unable to screw the trim. I was thinking of gluing it down. What kind of glue do you use to glue a metal trim to floor board?

3 Answers from MyBuilder Flooring Fitters

Best Answer

Hi adam78

If you're putting down domestic vinyl, then underlay is not needed. You will need to put down some plywood ideally 6mm, then the vinyl. I wouldn't recommend putting vinyl on top of floorboards direct because in time you will get problems.

Extra answer

I would use exterior plywood. No do not screw into joist - no need just straight into floorboards. I would use normally a screw that's not bigger than 20mm, or you can use ring shank nails but I think they only come in 25mm (I might be wrong on that)

I would go around the perimeter of the plywood screwing 100mm or so apart and depending of size of plywood in the middle... basically make sure there is no bounce.. there is no harm in putting more screws in but do not go over the top.

Have you took the skirtings off? If so, then leave about 10mm expansion gap around the room because skirting will cover this, if no skirting has come off, then it's not necessary.


It depends if you want skirting boards on I have seen people put skirting boards on top of tiles. If not, then I would cut the strips back with a hammer and chisel, fit the ply with maybe a 2mm -3mm gap. They are trying to sell something that is not necessary unless they have seen it and recommended it, I have not seen it but 9/10 jobs we fit 6mm ply and sometimes have fitted 4mm... 9mm I think is too thick, but it is up to you.... but make sure it's exterior.

I would if it's easy to take the bath panel off and then ply then refit the bath panel and then vinyl and maybe put a line of silicone round. ....a lot more cleaner job.

7th dec

Have you fixed the plywood down?? It shouldn't bow... But if it does a little you have no worries because you are only putting vinyl down ... If there is a big problem then maybe you should put more screws in so it's secure. And it's flat as possible... No need to put primer down as you are screwing down and varnish is completely wrong material... you're not glueing the vinyl down onto ply so you don't need anything else. If the area's a big concern regarding level of floor, then you can screed on top of the plywood to make it level or smoother. But if it's a temp and you are going to change it regularly, then don't worry too much.

Hmmm smooth side up .. The smoother the better.. But not essential.. Its wood so yes it will soak up water.. But when you put the vinyl down silicone around...

More than happy to help.. Hope all looks good. I normally use grip fill but it really doesn't matter something your local DIY will sell or screw fix ...

Glad to help you.

Hope this helps or please add more information if you need more help.



Answered 17th Dec 2013

Hi adam78

For any vinyl you decide to use, You will need to put down 6mm exterior plywood.
you can screw-down with 20mm screws into the floorboards.
I would go around the edges of the plywood screwing 100mm apart and 20 to 30mm in the middle to make sure there is no bouncing.
Please make sure the screws are flush to the plywood or better still a bit in!. This is to prevent damaging the vinyl.

I would install the vinyl and cut it neatly around the edges of the walls and then put a clear sealant around it.
If you are not able to cut neatly, you can get a color sealant of the same color of the vinyl, use it for the edges which will cover all the imperfection around the edges.
I hope I was able to help with these pieces of information.
Best wishes.


Answered 27th May 2020

Hi you can use 6 mm ply up to the edges screw 20 mm screws 150cm apart or you can do 200 cm apart then put 1 screw in the centre of each square.


Answered 13th Aug 2020

Post your job to find high quality tradespeople and get free quotes

Can’t find an answer? Ask a new question

Question Categories