Wetroom Floor Plywood Floor

[dumbrill]

Hindsights a wonderful thing. You could have had a wet ufh system laid in a screed to build the floor level up and incorporated the falls for the tray into the screed

I considered this, but in reality all that I loose is the thickness of the heating membrane.

 

[dumbrill]

The rate of expansion of steel is not very much. About one thousandth of a percent change per degree. Along a length of 1700mm and with a 20 degC temp rise the steel will expand by 0.4mm. I'm assuming that this is negligible.

Having looked further the coefficient of expansion of concrete is not much different to that of steel - depending on mix, see attached jpg. The figure for steel is around 10 x 10-6/degC. Therefore a steel subfloor or a concrete subfloor is not really an issue.

 

[Scott]

Personally id have gone for the concrete as the ufh is cheaper to run than the electric system. But its not mine it yours

Id still be inclined to go for the decoupling membrane as there is still room for movement in all directions.

 

[peckers]

I would still contact the manufacturers of the products you are using to make sure there suitable

 

[Sim101]

As you are taking up the floor anyway I would put extra noggings in as scottley has already said, you want to put them in at 300 centres. as the floor will be open it is better to make sure now rather then screwing down the ply and finding out there is still movement there. you could use 18mm ply and put a 6mm backer board on top of the ply and install the tray to suit the height.

Noggins make sense, but whats the advantage of backer board over a thinner sheet of ply? room will be tanked using the membrane from the Aquadec kit.

On another note I presume I have no need for a decoupling layer in this situation as, unlike dumbrill, i have no plans for underfloor heating in either area

 

[peckers]

You can go either way using tile backer or not, I was only offering an alternative as a tile backer board is a better substrate to tile onto and if it was me doing the job for you then this is the way i would recommend, fitt the membrane as per manufacturers instructions and you will be fine.

 

[wetdec]

Impey under board their trays in the install videos to strengthen them........

[ame=http://www.youtube.com/watch?v=3xekpG9Y22k]YouTube - Impey Aqua-Dec Wetroom Installation Guide Part 1[/ame]

 

[Sim101]

Thanks Wetdec,

while your here, would you recomend the dura -wp system that i see talked about on the forum to go with the impey tile safe membrane system?

if so, which order would you use them? i.e floor first or walls first

Cheers

Sim