Tanking floor - ply, liquid membrane, tile backer?

[Dave]

Just to add , I recommend sheet membrane as the one i use is also anti crack , which with thermal expansion in a timber floor would be beneficial to,prevent stress cracks to tiled installation.

 

[johnplum]

Thanks Dave. That's another good point.
It definantly needs a membrane, unless I build a dam.

 

[johnplum]

Why not use 6mm insulation boards and tank over the top, then tile ?

I'd like to keep it simple, and simplest most natural materials if possible. :mad2:
Personally, I think we be better off with downstairs baths or showers on a 2 square metre stone slab with a ceramic gutter complete surround - have a suspended decking walkway in winter for warmth. Easier to maintain and build. OK for wheelchair access if its a shower. And also, separate rooms for toilets! :smilewinkgrin:

One reason for not using insulation boards (a 'floating floor) is I think, that insulation is redundant on a suspended timber floor - timber is insulation. Maybe insulation boards are useful on a concrete floor. I could insulate it and add underfloor heating, as many are doing. I don't see the point in insulating it and then heating a suspended timber floor, when I can just let warm air rise from below and gently warm the floor. Wow!

 

[Chalker]

I'd like to keep it simple, and simplest most natural materials if possible. :mad2:
Personally, I think we be better off with downstairs baths or showers on a 2 square metre stone slab with a ceramic gutter complete surround - have a suspended decking walkway in winter for warmth. Easier to maintain and build. OK for wheelchair access if its a shower. And also, separate rooms for toilets! :smilewinkgrin:

One reason for not using insulation boards (a 'floating floor) is I think, that insulation is redundant on a suspended timber floor - timber is insulation. Maybe insulation boards are useful on a concrete floor. I could insulate it and add underfloor heating, as many are doing. I don't see the point in insulating it and then heating a suspended timber floor, when I can just let warm air rise from below and gently warm the floor. Wow!

I suggested insulation boards ( marmox etc) to build up the 6mm difference, and because they are waterproof and can easily be tanked. Which as a wet room it needs to be tanked . I always lay them with SPF , then screw. This is not a floating floor.

 

[johnplum]

Well, after this conversation, which guided my thought, I am clear on this now. It takes a while to think this , I needed to think, think again and sleep on it too, with all the options and claims.
I'm going to remove the 18mm ply, replace with 25mm, and tank otver that.

AS for bitumen sheet, I do fancy that, always did. It seems very expensive to me… perhaps I might find a cheaper supplier. WHich leaves me with a final question: :hurray:

I highly rate bitumen sheet and liquid bitumen from my building experience, so how does liquid bitumen compare to bitumen sheet as a tanking membrane? Would liquid bitumen and bitumen tape for seams be as good a solution as sheet, or not? Anyway, would liquid bitumen not be better for the walls?

A related question, How does liquid bitumen (applied in two or three coats) compare with liquid butyl compounds, commonly found sold as tanking solutions? None seem to use that.

Cheers, John