The best floor prep

[Do it Properly]

Hi Guys! I'm one of those annoying people who can't do the job myself but insist on it being done perfectly when i pay some poor guy to do it for me. Anyways here are my questions:

Current situation: 1st floor bathroom. Floor tiles removed to reveal 18mm floorboard with 6mm ply. Believe it or not this has been down for 7 years and not moved a bit! Anyway I know it's wrong and I want to rip it all up and start again. So imagine we are down to just joists and nothing else and we want to lay expensive natural stone down (not exactly what at the mo):

1). What size ply to WBP lay down and how to best lay it. Assuming ply is the way to go?)
2). I want to use Thermal Aquapanel and Devi underfloor heating - good idea and products? If not any other recommendations? Also using Thermal Aqua panel - does that mean i don't need insulation boards for the ufh (which is better?)
3). Good idea to tank around the new shower area - if so what to use?
4). What are the best grouts and adhesives to use?
5). Is it best to use a membrane and, if so, what, where and how to fit?

Please remember that this is a small bathroom (4m squared) so i am prepared to spend whatever it takes and don't want to skimp on any materials at all (please let me know what is best even if it seems overkill)

Thanks a million!

 

[brian c]

22mm ply and a decoupling membrane.

contact uheat on this site and they will advise you what to use.

two choices a paintable hit such as BAL WP1 or a rolled membrane,contact wetdecs for a good price.

mapei,pci,BAL ARE GOOD MATERIALS ...personally i use mapei.

why dont you get a professional tiler from the forum to give you a quote on the job,saving you the hassle.

 

[DHTiling]

Are you putting stone on the walls as well..?

 

[Do it Properly]

Yes was thinking of using Limestone. Does this present any problems? Beginning to go off the idea of UFH now too as the level just seems to be rising too high. The old tiles, ply, etc took up 36mm and I need to kee around that level due to the adjoining passageway. Seems like the extra layers also add in more than you initially think due to the layer in between e.g backer board at 10mm plus an exta 6mm to join it to the ply! This is getting really confusing now!:mad2:

 

[DHTiling]

You don't need backer boards onto ply...ply does insulate some anyway.

Use 22m ply as brian has said then put ufh on top of that...use slc over the top and then an uncoupling membrane...the floor will be around 30mm thick then you have tiles on that...so not a great big height difference...

As for the walls depending on the limestone you might need backer boards to take the weight....some limestones are only around 25kg per sqr mtr and are fine onto plaster board( 12.5mm) tanked...but a safer option is a backerboard...

 

[hillhead]

are the walls up to the weight of the limestone???

 

[Do it Properly]

Re the walls - mostly stud that are now fully exposed so can be strengthened with noggins and AquaPanel attached (assuming AquaPanel is a good one?). Was thinking of tanking the solid wall as the shower will be on that one and then tiling on it (OK?).

Dave - Thanks mate! But what is slc? I'ver seriously gone right off the ufh idea now so I can just use 22mm ply and the uncoupling membrane (can you recommend one? What does it actually do and what thickness does it add as it looks like it needs to be bonded to the ply?)

 

[DHTiling]

The uncoupling membrane is ony 3mm thick..it will prevent stress fractures from the thermal movement in the ply from transfering to the stone...

 

[Do it Properly]

Fantastic! That's just what I need then. One last favour please, can you please tell me the exact name of the adhesive and grout you would recommend for this kind of job? Also what I would use under the membrane to bond it with the 22mm ply. Thank you so much!

 

[DHTiling]

I would use Mapei keraquick for the tiling and bonding the membrane...BUT maker sure you add noggins betwen the joists at 300mm intervals to make sure the floor is solid..

 

[Do it Properly]

Dave u r a STAR mate.

My plan forward then is as follows:

Strengthen floor and walls with noggins as appropriate.
Lay 22mm ply wood (sealed on bottom and sides)
Layer of Mapei keraquick then membrane (ditra) I assume this is what you call the 'slc' referred to earlier?
Another layer of Mapei keraquick then the tiles
Grout (with???)

Last thing... do i need to be aware of any expansion gaps or anything like that during this kind of job? If so where and how big? Thanks!

 

[DHTiling]

THe slc is self levelling compound....which you don't need if not using ufh...( heating)..

Grout..?..Mapei ultra colour plus is great fors tone as its fast setting and doesn't slump in the joints...

Expansion gaps..leave a small gap around the perimeter of the room and Silicon with a matching colour to suit the grout and mapei do these for all colours of ultra colour plus..

 

[Do it Properly]

Dave I just noticed on some of your other posts that you recommend a 2 part adhesive for the underside of the ditra. Is this better than the tile adhesive and, if so, which is the best one to go for?

 

[DHTiling]

2 part depends upon the floor substrate and keraquick is very capable if the floor prep is solid.

 

[Do it Properly]

Guys - just wanted to say a big thank you for all your help with this! Must be nice being so knowledgable - I'm envious!