Bathroom Floors and Walls - Again

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Alucard7002

Another DIYer seeking advice. I had bought most of my materials (on the advice of the Topps Tiles shop) before I found this forum. Having spent hours of reading I think I may have to take most of it back! But before I do so I would appreciate the professionals’ input.

It is a first floor en-suite bathroom approximately 2.2m x 2.4m. I have stripped off all the old plasterboard from the two stud walls and will be stripping off the existing 18mm T&G chipboard flooring.

Floor:

The floor joists are 200mm x 50mm (8” x 2”) at 400mm (16”) centres. The existing floor creaks a little (but far less than the rest of the house) but when I jump up and down in the centre I can detect no discernable deflection or bounce (unlike some other rooms!). I plan to put in 200mm x 50mm noggins on 300mm centres well glued and screwed.

The tiles are nothing-special 8mm ceramics with a nominal weight of 16kg/m2. The adhesive I have is Topps Trade Rapid-set flexible wall & floor tile adhesive BS EN 12004 C2FT and the grout is Grout is BAL microflex Microban.

I had planned to put down a new 18mm WBP ply floor, glued and screwed with Spax 4.5mm x 60mm Flooring Screws at 150mm centres everywhere, but I have read numerous references to 22mm or 25mm as the minimum. If at all possible I would like to use the 18mm for 2 reasons:

  1. The usual one of the ‘step’. The existing bedroom carpet lies about 12mm above the existing 18mm bathroom floor, so with 8mm tiles plus nominal 4mm bed it’s a perfect match. But with 25mm floor it obviously will be 7mm higher. SWMBO is very concerned about the aesthetic effect and fears stubbing her toes on this ‘step’.
  2. I’ve managed to get the two 1220mm x 2440mm sheets of 18mm ply upstairs – just. That involved flexing the sheet to the maximum possible to force it past the banister and wall – I’ll have to repaint the wall! There is no way a 25mm sheet can flex enough to do this so it would have to be ripped along its length into two 600mm wide ‘strips’. With the 18mm I already have, I can rather neatly use two complete sheets with only one joint, but with 25mm I would have to three joints.

Question 1:
Would 18mm ‘do’, or is it absolutely essential that I battle it back downstairs and change it for 25mm with a lot more joints?

Stud Wall:
This will be one wall of the shower; the other is a traditional plastered block wall. The stud-wall is 80mm x 50mm (3” x 2”) verticals with only one run of horizontal noggins at the midheight. I plan to add 80mm x 50mm noggins at 300mm centres. I have bought 12mm WPC ply, Homelux Waterproof Matting, BAL grip BS EN 12004 D2TE and BAL microflex Microban. The tiles are nothing-special 8mm ceramics with a nominal weight of 16kg/m2.
If I used the ply - glued and screwed as the floor - I would have a nice single sheet with no joints in the shower area.
But I have read comments saying ply is a no-no and strongly recommending backing board instead - something like this:

Wickes *–*Building Materials*–*Plasterboard*–*Aquapanel Water Resistant Backing Board

I’m confused!

Question 2:
Should I wrestle the 12mm ply back downstairs and change it for the backing board – which would have a lot of joints?

Oh – last point; we built this house in 1990 and plan to live here for the rest of our lives, so I do want a ‘proper’ job, not just a ‘bodge it’ for a quick sale job.
 
So back to Wickes and exchange the ply for their backing boards then. What do I use to seal/tape the joints? Some special product or just butt them up tight and cover with the Homelux stuff?

I leave a couple of mm between each board. If you're covering all the boards with matting then no need to tape, just fill the gaps with rapid set until flush... then cover with the homelux stuff.
if you have a look at my photo album 'Bathroom', you'll see the same method from start to finish with cement boards in the wet areas covered with the matting.
 
The topps gear is fine.
Because the matting is waterproof you will be sealing the adhesive in, no air will get at it, the tubbed gear is a 'dispersion' adhesive, it needs air to get rid of the moisture content and set.. The cement based adhesives ahve an addative and set through a chemical reaction. The same reason you can't use tubbed gear on large format tiles, the adhesive in the middle of the tile would still be wet while the outer edge would set.
The same when tiling onto the matting, there will be no absorbtion and very little dispersion so use the same cement based adhesive for the tiles. check if you need grey or white adhesive before you start..:thumbsup:

Perfect sense! Easy when you know how isn't it!
I bought grey, not entirely sure why now! The tiles are cream/very light brown (dull sludge) and grout is white, so now that you have nudged me, maybe I will change it for white. I'll get some of that Corner Tape while I'm there too, my Silicon handling skills are good enough for garage/shed but not for SWMBO's bathroom.
 
Good idea, my mrs is the same🙂
I haven't used the tape but it certainly does look like the answer. Silicon joints and grout lines can make or break a job. Good luck🙂
 
all women tend to be darleks "you must obay"
bowing-036.gif
:lol:
 

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Bathroom Floors and Walls - Again
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