UFH and decoupling membrane which way round

[Stevoe]

Hello experienced craftsmen, I need a little advice. I am in the process of building a bathroom which is constructed so far as follows. The floor is normal chipboard floor which has been overlaid with 18mm wbp ply screwed at 300mm or less centers, all walls within the shower area are Wedi on stud wall or lightweight block the shower base is a Wedi Fundo and all other walls are covered with Marmox 12.5 mm, all joints are sealed with Wedi tape, Bal single part flexi adhesive was used under and over the tape. As yet I have not treated the floor but planned to use Durabase uncoupling membrane stuck down with Bal single part flexible and water-resistant adhesive, then electrical UFH, then self levelling flexible screed then more Bal then 300x400 travatine tiles, two other walls have porcelain the shower tray will have travatine mosaics and the biggest wall with a big mirror on will be oyster coloured slate. The shower area will be almost enclosed on three sides with walls the last opening will have a 800mm glass screen leaving 500mm of opening to walk in and out of.

My question is do I put the UFH down first then self levelling screed then decoupling membrane or is it Durabase then UFH then screed, the adhesive instructions say sealing is in with the mix (I think) but dont expect the area outside of the shower to get that wet, so a further question at the back of my mind is should I also seal the WBP ply?

 

[White Room]

Ufh, then slc, then decoupling membrane

 

[Stevoe]

Thanks for the speedy response whitebeam

 

[White Room]

No problem, just remember to use some thin tape to hold the wires down before you self level otherwise the slc could push the wires up and make you use more tile addy than is needed.

 

[Stevoe]

Another thread on this forum suggested hot-melt glue dotted at intervals around the perimeter of the ufl, was planning to do that, seemed like a good tip, thanks though for thinking for me, this is the first and I suspect last bathroom.

 

[White Room]

Thats good as well

 

[wetdec]

As you are using a text book overboard method you can use Dura-wp to uncouple and tank your floor (providing floor not over 8m2). The Dura-wp is a lot thinner than Dura-ci and so much easier to handle in your situation.

Your lay order would then be

Floor
adhesive
Dura-wp (sticking is easier now)
slc
adhesive
tiles

Trying to make it easier

.

 

[doug boardley]

As you are using a text book overboard method you can use Dura-wp to uncouple and tank your floor (providing floor not over 8m2). The Dura-wp is a lot thinner than Dura-ci and so much easier to handle in your situation.

Your lay order would then be

Floor
adhesive
Dura-wp (sticking is easier now)
slc
adhesive
tiles

Trying to make it easier

.

where would you sandwich the UFH Tony?

 

[wetdec]

Ah 00ps sorry missed it, on top of the membrane b4 slc the tape will stick real good to the membrane as well


.

 

[The Legend; Phil Hobson RIP]

I would agree with all above, I don't want to confuse the issue but Dural CI can go under ufh or over, without effecting thermal transfare

 

[wetdec]

Keep up we talking bout wp not ci :smilewinkgrin::smilewinkgrin:

.

 

[The Legend; Phil Hobson RIP]

I am keeping up we are talking de-coupling membrane in 1st post (CI) WP is a tanking memrane nothing to do with de-coupling

 

[wetdec]

As you are using a text book overboard method you can use Dura-wp to uncouple and tank your floor (providing floor not over 8m2). The Dura-wp is a lot thinner than Dura-ci and so much easier to handle in your situation.

As wp is a poly elastic core with fleeced surface it can be used in low traffic areas such as bathrooms, showers, wetrooms up to a size of say 8m2 providing the floor is 22-28mm plywood screwed to joist at 150-300 centres as per good practice.

In the event of latteral movement in the wood floor the fleece allows a release not unsimilar to the lower membrane of a specified uncoupling membrane as used on large high trafic floors such as kitchens halls conservatories etc where latteral movement is increased..

.

 

[Stevoe]

The Durabase I have is an uncoupling membrane a bit like a sandwich of thin plastic with raised discs on one side, bought it of someone on the forum, may even have been you Wetdecs. All I need to know really is do I fit the ufh first then slc then durabase then tiles or is it durabase ufh slc then tiles, I have two conflicting sets of advice and to be honest it makes sense to me either way. Thanks to all contributors so far.

 

[roberto1490]

wetdecs i see that you advise using durabase wp membrane on the wetroom floor if under 8 sqm if plywood is 22-28mm thick. the OP's plywood floor is 18mm and mine is 12mm, is durabase wp still chosen therefore over the ci matting?