Laying Porcelain Tiles 450x450

[jezza8366]

Hi,

i've conflicting advice on the correct way to lay 9mm 450x450 porcelain tiles, existing floor is brand new T&G 18mm board, one camp says

Exterior grade plywood at least 12mm thick (18mm thick is recommended)

another

aquapanel or similar insulation boards or "Ditra matting"

I've a low ceiling height and adding over 30mm is not really good and tiler won't warranty the work unless I go 18mm I've also read that

"An excellent alternative to exterior plywood is cement based backer boards. These are rigid, waterproof and only 6mm thick which is ideal when you do not want to raise the floor level too much."

Any advice much appreciated its doing by head in!! don't want to mess up 2.5k of tiles!

[basshunter]

take t+g up.replace with 18mm ply fixed at 300 centres.end of

[Matty A]

If ceiling height is a problem then i personally would screw the t &g down and use the ditra matting with flexible adhesive, it costs about £8 - £10 per m2 or you could remove the 18mm T & G and replace with 18mm Ply (WBP) screwed down to the joists..

Mat

[basshunter]

ok t***** for helping out lads........................we should charge for this service

[grumpygrouter]

Ditra isn't suitable as a "movement" compensator in this type of situation. it is designed to allow lateral movement between substrates, i.e expansion of concrete balconies in sunny locations for instance, not to absorb the up/down movement of a springy floor.

If height is a genuine issue, you the only real solution is either replace the chipboard with 18mm ply or use something like hardie backer or No More Ply.

If you take up the T&G and put ply down you may want to consider putting noggins in as well to give extra rigidity. Ply still flexes after all to a certain extent.

Grumpy

[Monsoon]

That's the key thing - Surface prep and a rigid floor.

I read a tip on here, place a cup of water on the floor and observe the movement in the cup as you simulate vigorous movement across the floor.

I took up the T&G boards and replaced with 22mm WPB ply in my wetroom.

Many of the jobs I've undertaken, there has been a battle between the cost/time/effort of belt and braces approach Verses Minimum standard quick n dirty.

All I can say is I have never regretted doing the former ...... the less said about the latter the better

[jezza8366]

Thanks for the replies

I did speak to Schulter and they said the substrate floor must be rigid, even and flat I said what does that mean? They said to British Standards 22mm ply glued and screwed every 300mm

My builder says the new T&G is nailed with ringshanked down and glued so the joints are prone to less movement than the ply as the existing boards are T&G. He says this is british standards, so my thought was well Schulter would be happy with that.

It's all getting a bit crazy!

[dptiling]

went to price kitchen /dinning room floor yesterday.
area of just under 40 m2.
the floor is chip board . so explained that it would have to be plyed.
customer said that tiles had been there before so opted to take so notice of my advise.
then phoned me to tell me he had ordered single part flexable adhesive.

next job .

had to call into a job ,where kitchen fitters had moved a base unit , and had to patch in some missing tiles in a utility room.
they had laid a tiled floor with under floor heating on hardboard.
when i had finshed replacing four tiles ,the women asked me to look at the kitchen floor .
the grout was cracking and a couple of tiles had broken.

im i wasting my time advising people. and should i just start to do the same.
at least i will get the call backs a few years afterwards.

[jezza8366]

I see what you are saying what also I guess from your last post I need to take in account is its also got 'wet' underfloor heating Ply is seeming to be the only way although my builder is insistant its BS flooring laid and spec'd

[GazTech]

Hi,

i've conflicting advice on the correct way to lay 9mm 450x450 porcelain tiles, existing floor is brand new T&G 18mm board, one camp says

Exterior grade plywood at least 12mm thick (18mm thick is recommended)

another

aquapanel or similar insulation boards or "Ditra matting"

I've a low ceiling height and adding over 30mm is not really good and tiler won't warranty the work unless I go 18mm I've also read that

"An excellent alternative to exterior plywood is cement based backer boards. These are rigid, waterproof and only 6mm thick which is ideal when you do not want to raise the floor level too much."

Any advice much appreciated its doing by head in!! don't want to mess up 2.5k of tiles!

Personally I would overboard with 6mm backerboard, flexi glued and screwed, and tile with 2 part flexible adhesive, and flexi grout.....Gaz
BAL Fastflex Powder & Liquid
A two part, rapid-setting, sulphate-resistant, water-resistant and frost-resistant floor tile adhesive and isolating, anti-fracture underlay, suitable for use in interior and exterior locations. Suitable for fixing ceramic floor and porcelain tiles and mosaics (including fully vitrified), dark natural stone and slate. Suitable for use on tile backer boards, glazed tiles, concrete bases, cement:sand screeds, tongue & groove floorboarding, plywood overlay, floating plywood/chipboard floors, ceramic/quarry tile/terrazzo/hard natural stone bases, vinyl tiles/sheet, mastic asphalt, steel, glass reinforced polyester (GRP), steel and galvanised steel. Conforms to BS EN 12004, Type C, Class 1F.
BAL Microcolour Wide Joint Grout
A fast setting, efflorescence free, water and frost resistant cementitious grout with water repellent properties and built in Microban® antibacterial protection to inhibit the growth of bacteria and black mould. Suitable for use with ceramic tiles, porcelain, marble, natural stone, glass and fully vitrified tiles with joint widths from 2-20mm in interior and exterior locations including power showers. The addition of GT1 makes this product suitable for use with underfloor heating. BS EN 13888 CG2F Grout.

• Set in 5 hours
• 12 colours available
• Water repellent
• Anti-bacterial
• BAL Admix GT1
  A polymer additive for BAL cement-based grouts. Not for use with adhesives. The addition of BAL ADMIX GT1 greatly improves the physical properties and characteristics of the grout.
  
  • Increased mechanical strength.
  • Increased flexural strength and flexibility.
  • Reduced water permeability.

[Holohana]

ARDEX 7001 single part flexible adhesive is designed to go straight onto floorboards!

maybe thats an option?

[Monsoon]

Is there such a thing a British standard for a surface to be tiled on?

We have building regulations which deal with stability from a structural POV. but thats a long way short of advising on a tiled substrate.

Just get your builder to overboard at a right angle to the T&G with WPB 18mm ply - job done.

How low is the ceiling that the additional 1.8cm is going to make that much difference?

Everything else is a compromise and lacks your tilers warranty.

[basshunter]

Go with what gaz suggests.

6mm hardibacker(dont lay it too tight together+span joints underneath best you can) 2part flexible adhesive and flex grout.
This is where i usually end up with clients once all the options are explained.
What size grout joint are you having?