Hi all - quick question about sub floor

[rhinatron]

Hi all,
Done a few tiling projects before, but now looking to do some work on my house. We have a first floor bathroom with original floorboard which we are lifting and using downstairs. I need to lay a new subfloor and was thinking of ply and backer board, but then I came across a new construction board from Topps Tiles (can't seen anyone else who does this)

It's a 22mm high density board which they claim can be fitted direct to joists without any ply.

has anyone used this before? We're putting in underfloor heating so the insulation qualities would be ideal, but i'm concerned about it being load bearing?!?!

Thanks in advance!

 

[Tile Shop]

Should be fine if your joists are in good condition and not like trampolines. Topps say its ok in the description but doesn't mention anything about joist spacing.

I'm familiar with a cement board from Hardie, called Hardiefloor. Its fully cement based rather than foam cored like the Topps version. For that to be weight bearing, the 19mm needs to be on joists at no more than 450mm and the 22mm, at 600mm. If these distances are exceeded, you will get deflection so additional joists or noggins will be required. I would "guess" that for the Topps version, the joists would need to be closer, maybe about 300mm.

So should be ok, but you really need to speak to Topps to give you more information, such as a datasheet or an installation guide. If they can't give you that, then find out who the manufacturers are and talk to them about your project direct.

 

[Bond]

Is it a square edge board or t&g. If it's sold as suitable for structural flooring , then it should be certified as such. As above would check on joist spacing requirements, fixing method and if any additional supports are required.

If in doubt best stick to tried and tested flooring materials.

 

[rhinatron]

Should be fine if your joists are in good condition and not like trampolines. Topps say its ok in the description but doesn't mention anything about joist spacing.

I'm familiar with a cement board from Hardie, called Hardiefloor. Its fully cement based rather than foam cored like the Topps version. For that to be weight bearing, the 19mm needs to be on joists at no more than 450mm and the 22mm, at 600mm. If these distances are exceeded, you will get deflection so additional joists or noggins will be required. I would "guess" that for the Topps version, the joists would need to be closer, maybe about 300mm.

So should be ok, but you really need to speak to Topps to give you more information, such as a datasheet or an installation guide. If they can't give you that, then find out who the manufacturers are and talk to them about your project direct.

Thanks for the reply, my joists are solid but are at 400mm. have been into a few topps sites, but they don't seem to know much about the product.

also, tileflair have told me that I can use 6mm no more ply, instead of 18mm ply. i.e. straight onto the joists.... what are your thoughts on that?

it's a big room (4mx3m) so relucatnat to try anything crazy... would 22mm marine ply plus a backer board be the way forward?

Cheers in advance!!!!

 

[Bond]

With floor joists at 400mm centres, l think they ment you can Overboard with 6mm NMP.

Structural ply 18 or 22mm will should be fine overboarded with 6mm backerboard. Stagger board joints , and fit noggins where boards join. (Between joists and 90 degrees to them).

 

[rhinatron]

With floor joists at 400mm centres, l think they ment you can Overboard with 6mm NMP.

Structural ply 18 or 22mm will should be fine overboarded with 6mm backerboard. Stagger board joints , and fit noggins where boards join. (Between joists and 90 degrees to them).

thanks, given the size of the room (3m x 4m) would 18mm be ok or would it move?

will be sistering some joists and adding noggins as we're having a free standing bath as well.

cheers

 

[Bond]

thanks, given the size of the room (3m x 4m) would 18mm be ok or would it move?

will be sistering some joists and adding noggins as we're having a free standing bath as well.

cheers

Personally l would go with 22mm, for piece of mind. It's the same amount of work and the cost difference is very little, at the end of the day. You can also get 25mm ply . ( might be overkill though).