Best board to use for sub floor?

[reg091]

I need to rip up wobbly old floorboards and replace with a flat surface to lay vinyl over.

To be level with the rest of the finished floor whatever I use needs to be 18mm thick.

OSB3 or Structural softwood Plywood seem to be the best options, with plywood being more expensive.

Any advice?

 

[acurachris]

I suppose either would do although you'll need to make the joints over joists and provide noggins where any square edges meet. You could use a P5 flooring grade tongue and groove chipboard (not everyone's favourite! ) which shouldn't require noggins under the joins as the T&G will help with the support when glued together.

18mm T&G recommended for joists at 400mm centres and 22mm T&G recommended if your joists are 600mm centres. Lay the longest length across the joists.

Can you not just replace with floorboards?

 

[^woody^]

If you are laying vinyl over a timber floor deck, then you should have an additional layer or thin ply or hardboard (6mm or 3mm) cross bonded with the deck. Otherwise the floor deck joints will show through.

 

[charliegolf]

Woody, I'm genuinely not being arsey, but why won't the joints show on the top ply layer?

 

[reg091]

Can you not just replace with floorboards?

Thanks for the info - excellent. I am looking at a) the cheapest solution and b) something that I can lay click vinyl on without having to raise the height any further. If raising the height wasn't an issue then I would leave the floorboards and lay ply on top.

 

[reg091]

If you are laying vinyl over a timber floor deck, then you should have an additional layer or thin ply or hardboard (6mm or 3mm) cross bonded with the deck. Otherwise the floor deck joints will show through.

I didn't know that. I assumed that joins in a ply/chip/OSB subfloor wouldn't show through underlay and vinyl, I have somew samples of click vinyl and I am surprised at how thick and rigid it is (I expected it to be floppy!). I can't see how 1 or 2 mm joins would show through that. (Or even T & G floorboards for that matter, but all the wisdom says they do show through).

 

[^woody^]

click vinyl and I am surprised at how thick and rigid it is

"Click vinyl" is not vinyl in the common use of the word - vinyl is the stuff that comes on rolls and is relatively thin and flexible.

For traditional vinyl, a structural timber floor and deck will move or deform slightly and joints will show though. So a layer of additional board will prevent this movement affecting the vinyl above

You need an underlay with click vinyl for different reasons - to protect the joints from an uneven floor and for sound absorption.

 

[reg091]

Cool, that makes sense. Thanks Woody.