Tiling Adhesive for 25mm plywood

[maltaron]

Advice or your preferences please: I am tiling with porcelain tiles on 25mm plywood base and have a choice of the following adhesives:

Ultrapro Rapid RS Flexible

Granfix Fastset Flexible

Nicobond Quickflex

or readymixed on Ebay number 1406299269231

TIA

 

[Richard C]

I assume this is a floor & it’s WBP not standard ply? What’s the ply laid over & how did you fix it? Did you acrylic prime the back & edges? What size tiles are they?

A BAL man myself & would generally use Rapidset Flexible but SPF is good & gives a longer pot life. Not familiar with Ultrapro but Granfix is OK, Webber or Mapei (but not the one in BNQ). Drew a blank on the Ebay number but forget any sort of tub ready mix; you should never use it on floors & it’s not suitable for tiles much larger than 250 x 250mm.

 

[maltaron]

Many thanks for your prompt reply. It is a floor and is new build with 25mm WBP plywood directly on 8" X 2" joists at 400mm centres, with glued edges. The tiles are 330 x 330. I will probably go for Granflex as this is the cheapest option.

 

[Tel77]

I'm looking to do the same or similar and have spotted a couple of comments through various threads about using acrylic prime the back and edges of the boards which I'm glad I've found out about now.

Is it necessary to acrylic prime the front surface as well before laying the porcelain tiles on the front of the WBP?

 

[Maxsys]

I'm looking to do the same or similar and have spotted a couple of comments through various threads about using acrylic prime the back and edges of the boards which I'm glad I've found out about now.

Is it necessary to acrylic prime the front surface as well before laying the porcelain tiles on the front of the WBP?

It depends what the adhesive manufacturer recommends

 

[Tel77]

Can I ask what the purpose of priming the back & edges is?

I can take an educated guess that the benefit of doing the edges is to stop the laminates seperating on the WBP but can't understand the reason for doing the back?

 

[Richard C]

Many thanks for your prompt reply. It is a floor and is new build with 25mm WBP plywood directly on 8" X 2" joists at 400mm centres, with glued edges.

Sounds good but you don’t say what the joist span is! Is this a bathroom or another area?

The tiles are 330 x 330.

Use a large format trowel.

I will probably go for Granflex as this is the cheapest option.

Granfix is OK but you should remember that quality really matters with this stuff & you generally get what you pay for! Are your tiles polished or glazed porcelain? Polished porcs require sealing but some come pre-sealed; check with your supplier. With polished porcs, you also need to be careful with adhesive colour or you could get bleed through staining, what colour are your tiles & which Granfix addy are you proposing to use?

 

[Richard C]

I'm looking to do the same or similar and have spotted a couple of comments through various threads about using acrylic prime the back and edges of the boards which I'm glad I've found out about now. Is it necessary to acrylic prime the front surface as well before laying the porcelain tiles on the front of the WBP?

Priming the front face of ply is not normally required but you should follow your chosen tile adhesive manufacturer’s recommendations; some state specifically not to prime. Read my response to maltaron regarding polished porcelain tiles.

Can I ask what the purpose of priming the back & edges is?

It’s to reduce the risk of moisture penetration into the ply underside & edges; although WBP is made with waterproof adhesives, it’s still wood & wood is not dimentionally stable when exposed to moisture/water; if it get’s in, the ply can warp & there go your tiles.

I’ve answered your questions because they may be relevant to the OP but please don’t hijack someone else’s thread. It can lead to confusion over who said what to whom & result in incorrect advice being given; it’s also against forum rules! If you post questions on your own thread you will get a much better response & avoid the OP getting ****ed off by hijacking theirs!