I've got a wetroom job to price up..you'll see from the photos it's a very small room with a sloping ceiling, which will have a velux window..

The whole room is to be the wetroom (no glass shower wall) and the tiled floor is to be sloped down towards the shower gulley..it will have a wall hung WC and basin so no worries about levelling them up on a sloping floor..all the walls and sloping ceiling are to be fully tiled..

I plan to use a tuff2 grp former tray, plywood the remaining floor boards, fit durabase wp over the ply and tray, lay ufh on the ply area (undecided about ufh on the tray), cover ufh with a either slc or flexi adhesive with a slope towards the tray..I also plan to fit durabase wp on the walls and sloping ceiling..

The floor tiles will be natural stone and I suspect natural stone mosaics on the walls and ceiling..

My main questions are...is durabase wp going to provide sufficient bond on the sloping ceiling? and is durabase wp on the floor going to provide sufficient uncoupling, given that it is a very small floor area?.. any other comments also welcome...

What is the ceiling construction..?

Originally Posted by Dave

What is the ceiling construction..?

The ceiling is currently lathe/plaster but will be ripped down and replaced with a moisture resistant plasterboard..it can change if you think something else is more suitable...

Thought thats what it was in the pic..

Personally i would use a cement backerboard for added security...making sure plenty noggins and extra strengthening if needed... the truss's need to able to support the extra weight.

The tray you have chosern are easy to use and the |Dural membranes are the way to go.. also make you sure to use the joint tape for all seams.

Originally Posted by Dave

Thought thats what it iwas in the pic..

Personally i would use a cement backerboard for added security...making sure plenty noggins and extra strenghtening if needed... the truss's need to able to support the extra weight.

The tray you have chosern are easy to use and the |Dural membranes are the way to go.. also make you sure to use the joint tape for all seams.

Cheers Dave..your input much appreciated as always...

Yes on both counts.

The Dura-WP tanking membrane will uncouple the floor for you up to around 8m2 providing its not a heavy traffic area such as a kitchen etc. To use the floor should be either over boarded with 10/12mm ply wood screwed at 300 centres or renewed with 22/25mm ply fixed the same.

On the ceiling, board out with 12.5 pb and fix Dura-WP membrane before tiling or go Dave's way. Your call on that one we cant see it or know what you are going to find


..

What are the dimensions of the floor joists? Does any plumbing need to be drilled through those joists?

Haven't converted my plywood dimensions but with both my last two (only two) wetrooms we started with 5/8" ply over our 2"x10" floor joists and then topped that with 1/2" plywood.

I like to leave a little room for expansion on the top plywood and silicone this gap. We often are heating these floors so we add our cable heat and cover that with a sandwich of modified thin set over the floors and wire ( 1/4" x 1/4" margin trowel) and top right away with a 5-1 mix (5 Parts sand 1 part cement) - This layer we grade to the drain.

Once this floor sets up a little (2 days) we go back and cover with an uncoupling Membrane and waterproofing.

I have had good luck recessing the drain below the subfloor so we can achieve a 2" height from top of drain to top of finished floor with only a marginal transition into the bathroom.

I'm building a new curbless as we speak and have started the framing changes. I have a Kerdi drain under flood test as we speak. I will be using a trench drain from ACO at the doorway.







Good Luck.

Drilling through joists is not recommended, actually its against building regs.

Here we can drill through the floor joist so long as the hole is not within 2" (51 mm) of the floor joist top or bottom. The aid with deflection most times the joists have been double up (glued and screwed). My structural engineer does not like many holes and often will call for a second stud or mechanical fastener to tie it all in but most times it's just basic wood framing.

I like to over kill the floor assembly by adding solid or cross blocking on 4' (1.2 meter centers). I can feel the difference on every job and love the piece of mind of waterproofing (Tanking ?) off of a solid foundation.

Originally Posted by diamondtiling

Drilling through joists is not recommended, actually its against building regs.

Dom, I would love to see that here in the building codes. One of the most dangerous and destructive forces on the jobsite is a plumber with a sawzall or holehawg!

not sure if it's strictly against the regs. Four yrs ago I had a sheet with 'regulation' on holes and even notches, but, that was four yrs ago. Not that anybody pays any attention when they have pipes to lay

Hi John, You know I don't include you in my list of plumbers butchering joists!

Our standard codes for dimensional lumber state it's OK in the middle third on the vertical dimension, but not within 2" of the lower or upper edge of the board (as John W noted). There is also some infomation about drilling anything within a certain distance of the end of the board (where it has bearing strength). I think this is a no-go within the outermost 18" of the joist. It's also a no-go in the middle third of the span.

For engineered stuff, all bets are off, and the manufacturers have all sorts of do's and don'ts for those.

So I'm not supposed to put my 4 inch soil through 9 inch joist.??

because it takes me forever with that holesaw and right angle drill

4" soil stack through joist.

Don't you just cut down 5" left and right and kick it with your boot? That's how it was done in my parts back in the day? I've seen some bathroom floors that seem to stay put because of an act of god after all the plumbers notches...

We don't drill any holes larger than 2 3/8" and will start modifying the framing if we need 3 or 4" lines in an area.

Originally Posted by faithhealer

not sure if it's strictly against the regs. Four yrs ago I had a sheet with 'regulation' on holes and even notches, but, that was four yrs ago. Not that anybody pays any attention when they have pipes to lay

If you put a hole through a joist for pipework you are supposed to add noggins either side of the hole to add strength.

Originally Posted by Rob Z

Hi John, You know I don't include you in my list of plumbers butchering joists!

Our standard codes for dimensional lumber state it's OK in the middle third on the vertical dimension, but not within 2" of the lower or upper edge of the board (as John W noted). There is also some infomation about drilling anything within a certain distance of the end of the board (where it has bearing strength). I think this is a no-go within the outermost 18" of the joist. It's also a no-go in the middle third of the span.

For engineered stuff, all bets are off, and the manufacturers have all sorts of do's and don'ts for those.

hi Rob
thanks for explaining the regs so elanquently, you saved me trying to explain our regs
which just happen to be the same

its based on the downward pressure on the floor joist and where the internal stresses lie

woods woods whichever county its used in and is subject to the same stresses and limitations

there are safe zones and critical zones,if you drill through a critical zone you may weaken the joist and lead to its failure

carpenters, plumbers and electricians are taught these principles everone else is told not to drill through a joist unless it is checked and marked out by a competant and authorised person

Mike, some of the engineered lumbers can't be drilled in at all. A buddy was on a jobsite onetime and the sparkies drilled a bunch of holes in the engineered beam that was installed to carry the load of the addition above. The inspector flagged it and it had to come out. I can just imagine the fireworks over that one.

As a general contractor, I tell all subs onsite - plumbers/sparkies/HVAC - if they want to cut or drill something to see me first, and often times we do it for them.

Hi Rob
same here with engineered joists, if they need to be drilled it has to go in the specification to the manufacturer, you cant just drill them