New house - bathroom floor, mixed advice

[Geed]

Hi

Going to be helping with tiling the upstairs bathroom floor in a new house. Just bare flooring right now.

I've read / watched just about every bit of advice from just using PVA to seal the boards first and then tiling directly on top with a flexible adhesive to putting down ply then backer board then matting then the tile. All this different advice coming from tile shops and "pro" YouTube videos.

What is the proper way to do this?

Thank you for all your help

 

[Steve6690]

View: https://youtu.be/U6GYjXJFUXY


They do an adhesive spray foam now which replaces the screws and tile adhesive. That's how I'd do it.

https://www.ctdtrade.co.uk/hardie-backer-fixing-foam

Don't use PVA.

 

[jdnest]

Hi Geed

Sounds like you're having fun 😉

Everyone will have different ways of doing it I'm sure, but I would do belt and braces and...

Seal the ply edges and faces twice with an SBR type primer, Ultra Tile Pro Primer (CTD) or equivalent... Screw those down properly.

Then S1 adhesive, Mapei Keraflex Maxi or equivalent, then screw down backerboards over that. You can SBR prime these boards too, I always do, but I probably go overboard, but don't see why not...

Always check levels as you go to ensure it's still straight due to the adhesive layer.

IF you want to go all out you can then apply a membrane such as Ditra/Durabase. Use the Ardex AF200 to stick it down instead of adhesive, if you want to keep the height increase to a minimum.

Then usa an S1 adhesive to install the tiles.

No need for the Hardieback boards or Ditra though if you're installing LVT/vinyl tiles on the floor though, only needed for ceramic/porcelain/etc tiles.

Hope that helps...
J

 

[hk940]

I am surprised at the Hardi-backer video, here in the USA. the tile Council of America states a min. of 1 1/4" subfloor.
Hardi-Backer, Durock, Wonder board etc. are not structural and does not contribute to the min. sub floor specification.
When I had my business (26 years 50 setting tile) 99% of floor installation was done over 1 1/4" plywood (top layer exterior rated)
Using the proper thinset (Mortar Adhesive) and correct floor prep, cleaned washed and screwed every 8".
I never had a call back.
I don't like using Hardi backer because it makes the thinset (Mortar Adhesive) set up in a matter of minutes, making any adjustments impossible (with out breaking the bond)
The Durock, and Wonder Board brands absorb less.

 

[Dave]

Just to add , 5385 standard does not recommend tiling direct to plywood anymore. Use a backer board like Hardibacker etc. Tape the joints with Hardibacker joint tape and tile with a S1 adhesive.
Deffo no PVA.

 

[hk940]

Just to add , 5385 standard does not recommend tiling direct to plywood anymore. Use a backer board like Hardibacker etc. Tape the joints with Hardibacker joint tape and tile with a S1 adhesive.
Deffo no PVA.

I assume the 5385 standard is in the UK. Here in the US setting on the proper plywood with the proper mortar is OK.

 

[Dave]

I assume the 5385 standard is in the UK. Here in the US setting on the proper plywood with the proper mortar is OK.

Yes , it’s been outlawed in the UK.

 

[Ben-gee]

To be fair to hk940 this is more a reflection on the poor quality ply that we now seem to get in this country.

 

[hk940]

To be fair to hk940 this is more a reflection on the poor quality ply that we now seem to get in this country.

The quality of the plywood here has gone down too. The good stuff A/C or B/C, but the price is out of sight.
Nothing is the size it used to be, 3/4" forget it. 1x4 used to be 3/4x3 3/4 now its 3/4x3 1/2.
If you want to do any kind of cabinet work you need special router bits because 3/4" is too big.

 

[Bladd]

On my reading the 5385 standard advises against tiling on ply on the wall. Doesn't advise against it for the floor.