Discuss Moisture in floor advice...please in the UK Tiling Forum area at TilersForums.com.

Renovated the bathroom on my 1970
bungalow last year. Took up the old pink floor tiles with sds. Chunks of what i assume is self leveller or maybe screed (?) came up with them.
Left with Concrete slab. laid insulated coated (cement topped) tile backer boards (marmox) using a thick amount of flexible tile adhesive to make floor completely level. Laid 6mm marine ply over top of boards and then vinyl (for warmth).
Fast fwd 12 months, pinky stains through vinyl. Took it up, mould on underside of vinyl.
Took 6mm marine ply up, seems a bit brittle like it has moisture but nothing too bad. Bought floor hygrometer placed on backer boards and after 24 hours it's showing 75% (and it's been dry here for weeks).
So quite high.

I'm guessing I need a dpm and I know it should go under the tile backer boards but I don't want/can't take them all up (glass shower and tray is in) so I dont want to take that out again nor be using sds in there taking up all the tile adhesive underneath with chips flying everywhere. Ps. I cant add much more height.

I've bought tiles (porcelain, impervious to moisture) which should be more moisture forgiving than vinyl. Can I use a liquid dpm on top of the cement topped tile backer boards? Or even a normal dpm? Or am I better with some sort of ditra mat type thing and then tile on top of that? Ideally I'd like electric ufh with the tiles but realise that may make the relative humidity worse.

I know everyone will say take the tile backer boards up , lay dpm and put new tile backer then electric ufh then tile. But just checking if I can do anything else on top of existing backer boards....... 🙏 picture to show type of backer board as i was taking marine ply up. The stains on the top side of ply are just the old vinyl glue not water as such.
 

Attachments

  • 20240522_092041.jpg
    586.9 KB · Views: 134
  • 20240522_091918.jpg
    529.7 KB · Views: 77
  • 20240522_091908.jpg
    485.3 KB · Views: 75
Clean up the timber floor, remove toilet, level up the uneven area, apply SBR then install the Ditra Matting. It can be done. Send us pictures.
Thabkyou.
I've just removed the marine ply a minute ago. Ditra mat on top of those tile backer board still OK and will that stop the moisture coming up?
 
Thabkyou.
I've just removed the marine ply a minute ago. Ditra mat on top of those tile backer board still OK and will that stop the moisture coming up?
send picture

make sure the tile backer boards are well secured to the floor. Apply SBR then Ditra. Using Ditra mat will stop the moisture migration
 
Last edited:
Measured the floor with a floor hygrometer, rained yesterday and the RH on top of the boards was up to 82%. Seems to sit about 70% without rain.
Tile and vinyl say 75% RH maximum permissible level So I definitely need some sort of moisture barrier.
Tiler is recommending using some self levelling then epoxy resin on top to stop moisture.

Confused as to whether to do that or the ditra mat. Obviously the mat is easier.....

Thoughts anyone?
 
Yep, he said to use self levelling over the marmox multiboards and then paint a 2 part epoxy resin dpm.
He will tile over that he said.
That is bad practice.

I noticed you have a shower enclosure there; did you check for any leakage? Those suspended shower trays tend to leak.
 
That is bad practice.

I noticed you have a shower enclosure there; did you check for any leakage? Those suspended shower trays t
Oh is it?

No I checked for leaks underneath the tray. All seems dry.

All rooms concrete floor read similar 75+ RH with the hygrometer, give or take a couple of percent so pretty sure its due to moisture/vapour coming up from ground but the carpeted rooms deal with it obviously the vinyl would let the moisture out into the room though
 
That is bad practice.

I noticed you have a shower enclosure there; did you check for any leakage? Those suspended shower trays tend to leak.
So you would, sbr the backer boards and then ditra mat? Would you use flexible tile adhesive to apply the mat or something else? Thankyou
 

Reply to Moisture in floor advice...please in the UK Tiling Forum area at TilersForums.com

Subscribe to Tilers Forums

There are similar tiling threads here

Hi people I'm in desperate need of advice So my builder who I let go due to poor work has...
Replies
3
Views
1K
I had a small leak in the main water line before the stop tap in my 1950s house. The copper pipe...
Replies
1
Views
2K
Hi, Can anyone please give me some advice. I have an old bathroom and I want to turn it into a...
Replies
1
Views
907
I'm planning on tiling my porch, and the tiles and adhesive will take up around 13mm of height...
Replies
2
Views
624
I've recently bought Johnson 'Orkney Stone' ceramic floor tiles from B&Q. Paid to have them...
Replies
6
Views
1K

Trending UK Tiling Threads

UK Tiling Forum Popular

Advertisement

Thread starter

Joined
Location
Cornwall
What member type are you?
  1. Homeowner
Business Name
None

Thread Information

Title
Moisture in floor advice...please
Prefix
UK 
Forum
UK Tiling Forum
Start date
Last reply date
Replies
25

Which tile adhesive brand did you use most this year?

  • Palace

    Votes: 5 4.7%
  • Kerakoll

    Votes: 8 7.5%
  • Ardex

    Votes: 6 5.7%
  • Mapei

    Votes: 28 26.4%
  • Ultra Tile

    Votes: 14 13.2%
  • BAL

    Votes: 27 25.5%
  • Wedi

    Votes: 3 2.8%
  • Benfer

    Votes: 2 1.9%
  • Tilemaster

    Votes: 19 17.9%
  • Weber

    Votes: 18 17.0%
  • Other (any other brand not listed)

    Votes: 13 12.3%
  • Nicobond

    Votes: 5 4.7%
  • Norcros

    Votes: 3 2.8%
  • Kelmore

    Votes: 1 0.9%

You're browsing the UK Tiling Forum category on TilersForums.com, the tile advice website no matter which country you reside. Our UK based online tiling forum has 48,000 members and started out in 2006.

Top