Floating floor replacement in a downstairs toilet.

yes there will be a dpm/vapour barrier but this will be at ground level..i.e

soft sand..then
dpm/vapour barrier..then
your block beam..(suspeneded)..

so i would lay a dpm then screed s/c ontop off the b/b...
tile and leave a perimeter joint around the walls.

you have already removed the(dpm) from the floating floor...so you will have to replace this...

i am just a tile fixer mate not a biulder.. :wink
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Thanks, so you don't rate the idea of using the marmox board as a dpm and tiling on top as mentioned earlier in the thread?

i maybe old fashioned ere bud,but thats the way i do this type off floor,and i quite enjoy doing it this way..sand cement screed then float it,most mfr of b/b stipulate a screed ontop,but some house biulder replace this with insulation/dpm/chipboard...does the same job(but not good for tile fixing)..

but what you could do is call one of the adhesive mfr and get more info off them bud..

let us now how you get on.

best of

think i need to invest in another pc..wife doing her shopping.... :rolleyes: :rolleyes: :rolleyes:
just read thro the thread

Rich didnt know it was b/b construction mate..

i have never put marmox etc over this,so dont know if it will work or not.

but again give the mfr a call...you never now what the advice they will give you,it may work...

everyday is a school day.. ;)..(even for me)..
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It's a shame that I hadn't had your advice earlier, having bought and cut the boards already. I was going to go the screed route initially but was put off by the min 50mm requirement when I only have 56mm to make up and the tiles are 10mm thick ceramics... Wish that these house builders would do a better job to start with!
Having spent the money already, I'm in two minds whether to proceed now. I could be a pioneer here, or a dead guinea pig!!

There are air bricks externally so I know the underfloor (block beam)space will be ventilated .....
Sorry I’ve been unable to post earlier but I have been extremely busy this week.
It's a shame that I hadn't had your advice earlier
Nothing wrong with the advice I’ve given you so far m8; I did say you could still screed it, just be careful which type of screed you used;
Not all SLC’s can be laid to that sort of thickness & those that can are expensive. A bonded, granolithic or resin screed will be cheaper & can be laid much thinner than the 50mm recommended for an unbonded sand/cement screed.
No real experience with block beam floor construction but I also said I think it likely there would be a DPM under there anyway but laying another under a bonded or resin screed would not be a problem.

Correctly fixed the Marmox boards will provide a damp barrier & a rigid tile base which will work equally as well, just another way of doing it. Contact Marmox for reassurance if necessary, the main thing is you need to get away from a floating floor.
Richard thanks again and I was not criticising your advice by the piece you quoted! I'm sure you can appreciate that by getting more advice the better I can make an informed decision and hence why I said that to tictic. I apologise if it appears otherwise but that was not my intention and therein lie the vagaries of typed words!
I am going to proceed with the plan of using the marmox as you advised and am grateful for everyone's input thus far.
Richard- would using the mapei primer g be ok before using the adhesive on the concrete floor or is not needed with the flexi adhesive? It's a lot cheaper than the bal primer hence the question.
Assuming this is to stick the Marmox insulation boards down? Not all primers are the same, which primer are you talking about? BAL don’t recommend priming conventional sand/cement screed as a matter of course but weather or not you need one will depend on what type of screed you have (Anhydrite screed & Gypsum plaster must be primed when using cement based adhesive); if in doubt use an Acrylic or SBR based primer.

Personally I would only use products from the same manufacturer but Mapei primer should be OK.
Let us know how you get on Bob, it looks like you might have the same type of floor as us, and I'm desperately wanting rid of the horrible polystyrene/plastic sheet/wonky chipboard configuration in our kitchen....


A successful conclusion to your job might just spur me on with added confidence to do a good job of ours!!!! :D

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