advice needed,,,overlaying weirock boards weirock boards with ply,,,how thick???

[teenagedirtbag]

could someone please tell me what thickness of ply i should be using to overlay my kitchen floor before tiling it ??? its a weirock board floor screwed to a 2x2 frame which is fixed to a concrete floor,,,in a few areas where the tongue and groove meet a litte give has developed after walking on it for so long etc,,,only about a millimetre i would say,,,the floor is in great condition and totally flat and smooth,,,i just want to give it a ply overlay to strengthen so the tiles dont crack when walked on due to the slight give in a few spots,,,any advice would be greatly appreciated......

[Ken Bruty]

By your description, it sounds like your wood floor is a floating floor (engineered wood or laminate or real t&g wood on battens), if so, I would recommend that you remove the boards and the frame back down to the concrete and tile onto that, it would be more cost effective if the floor is sound and you would be less likely to have movement issues with the subfloor, as I don't think your existing floor would cope with the extra weight if it's already moving now.

[Ken Bruty]

Oh and welcome to the forum.

[Dave]

The frame is fixed ken.. so as long as the deflection is at a minimum then over lay with minimum BS standard ply..

But also it would be better if we knew what you intended to tile with tile wise..?

[Ken Bruty]

I agree Dave, just being safe 'cos I can't see the deflection myself

[teenagedirtbag]

aye the frame is hilti nailed down to the concrete,,,ita a full perimeter frame with horizontal battons every 40 cm or so with 240cm x 60 cm boards pn top screwed down,,,the only bit give is where the tongue and groove meet in a few places,,,i was supposed to use wood glue on the the tongue and groove but thought it would be ok,,,taking the floor back up is not an option,,,i read somewhere that 15 mm ply is used on floorboards etc but thought this sounded far too thick???,,,the tiles are ceramic matt black from b&q about 6 or 7 mm thick,,,330mm x 330mm,,,id have to use a flexible adhesive aswell wouldnt i???,,,ive only floor tiled once before but made a great job of it,,,how much would a tiler charge per sq mtre???,,,its about 20 sq metres...

[mikethetile]

hi the bs standard it 15 mm minimum

you can use glue stitching to retro glue the joints, its a bit time consuming but ive done it in the past to great effect

drill a series of holes through the top lip only and fill with pva glue, the holes need to be about 5mm and spaced about every 30mm, once the pva has set check again for deflection

if you have no deflection you could overboard with a tile backer board

but if there is still movement it would still pay you to overboard

[teenagedirtbag]

sounds like a great idea mike,,,i think ill go with the glue stitching,,,whats a tile backer board??? just thin ply???

[doug boardley]

sounds like a great idea mike,,,i think ill go with the glue stitching,,,whats a tile backer board??? just thin ply???

it's a cement based board 6mm thick, you fix it using flexible adhesive and screws