Ask a Tradesman
Tiling kitchen floor
we are planning to tile our kitchen floor and was wondering what is the best type and thickness of wood to use before we lay the tiles over floorboards.
12 mm plywood- seal it- then use flexible adhesive & grout with the tiles
Answered 28th Feb 2012
I use BAL adhesives for my tiling and they will not guarantee an installation with their flexible adhesive and grout unless ply is used to a minimum thickness of 15mm. However it is common practice among tilers to use 12mm ply as it more readily available and cheaper. The 3mm difference is unlikely to have a significant effect on the installation. BAL know that this is common practice and therefore don't have to guarantee most of their installations.
What is equally important is fixing the ply to the floor below. I personally believe that it should be fixed at 150mm centres with good quality screws that are the right length to properly engage the floor below. A 20mm screw through 12mm ply is no good leaving only 8mm of bite wheres a 40 or 50mm screw would be iffy as you could end up hitting pipes or wiring if they are fitted too close to the top f the joists. A 25 or 30mm screw normally does the trick and I should stress that this s an application where I would definitely not recommend using cheap screws. They need to bite.
Finally all decent tile adhesives typically have a manufacturer help no on them. If in doubt ring them and they will advise accordingly. They do tend to cover themselves well with their answers but you will at least know what the belt and braces solution is.
Answered 31st Mar 2012
The appropriate grade of board for flooring will be a minimum
15mm thickness of either Marine or WBP plywood (BS5385 part 3) with the
exposed back and edges protected from moisture ingress with a water
resistant sealer (Tilers primer SBR is acceptable).
Counter sunk screw fixings at a minimum 300mm centres should secure the
boards to joists and noggins where joints between boards should also be
coincidental with the support below.
Answered 29th Feb 2012