Bath/Shower Wall Lining Question

[JamesD]

Hi all,

Got a question regarding my spa/shower set up and waterproofing it. Am doing it myself and am working through the learning curve, slowly, oh so slowly, but surely.

I have recessed the spa in the studs 15mm or so, so according to James Hardie wet area install guide this would make it an 'external' tray? is that correct?

I have places some galvanised steel angel down the corner, and then I put up the villaboard, butting up in the corner and overlapping the spa.

Much to my delight :eek: I have just seen that for 'external' shower/spa trays flashing is required under the villaboard and over the steel angel. Is this correct? Is this my only option?

I see that for 'internal' shower/spa trays you can place the flashing over the villaboard. If that is the case, then why can't the same apply for an 'external' set-up, assuming that I take the vertical corner flashing down to the end of the villaboard, ie, over the recessed lip, shouldn't that be ok?

I had originally planned to:
* villaboard over the spa lip
* silicone up the vertical internal corner and along the horizontal edges
* apply undertile waterproofing, fibreglass sheet and apply 2nd coat of waterproofing
* and then tile, (already have a compatible tile adhesive)

I am assuming now that this is no longer enough. Is that the case?

I have planned to run flashing around the base of the bathroom. It is specified that I should only adhere the base of the flashing to the floor and not the wall, using Hydraepoxy 501. Would Sikaflex be ok to use under the flashing instead?

If anyone can offer any advice I would be really really grateful.

[JamesD]

PS: the bathroom floor is concrete, and I am planning on putting up 50cm wall and floor tiles, just in case that is important. Thanks

[Carpenter]

mm James, mm. There is no such thing as cm in building. The information about flashing under the villaboard sounds like the most thorough method, but unless you intend to rip it all of & start again thats not going to happen. The lip on the spa & corresponding overlap of the villaboard is pretty good, your idea about applying silicon at this junction is extra security well worth the effort. I would be tempted to use the Sikens polyurethene here, its a great product. If the recommendation is to use epoxy on the floor, I'd do that. Just remember, your taking on a task that is usually done by specialists, you only get one go at waterproofing & the cost of failure is expensive, so be thorough & dont skimp when applying the waterproofing compound. That thin layer is all thats between you & disaster. I assume your using an acrylic compound? Maybe even a second layer of glass & re-apply the goop. Ask yourself if the end result is going to withstand tilers crunching bits of broken tile into the waterproofed layer as they walk around. I use to do my own waterproofing with the acrylic products, but since it now requires a certificate from a licensed waterproofer (in NSW) I get it done by Wetseal Australia. The fibreglass system is much tougher & methods they use tried & tested. I'm happy to sub it out & be free of the potential headache. What I'm saying is I don't recommend that inexperienced people do this work, & I recon its not a good stage of the construction process to be looking at making a monetary saving. Its not that its a hard or difficult task, but all it takes is a pinhole & your rooted.

[JamesD]

Carpenter,

Thanks for the advice. I am using an acrylic warterproofing. the waterproofing tub suggests that I apply it 1800mm up the internal corner, this I will do, fibreglass and recoat. I was thinking that it would also be a good idea to apply it all the way up the walls in the spa shower area?? Surely the villaboard needs some sort of waterproofing behind the shower tiles?

Regarding the flashing, what do you think about attaching it over the villaboard along the horizontal and vertical lines. I feel that this would be a really good fail safe, so long as there was a small overlap over the lip of the spa? If so though, how should I go about attaching it to the villaboard and will the waterproofing compound ahdere to the flashing?

Any advice/further advice you could give would be great as I am desperate to get to the bottom of this one myself.

PS, sorry about the cm thing, (suitably ashamed). I have just checked my building bible and seen that it is, indeed, the second sin of building. Hanging head in shame.

[mic-d]

Carpenter,

Thanks for the advice. I am using an acrylic warterproofing. the waterproofing tub suggests that I apply it 1800mm up the internal corner, this I will do, fibreglass and recoat. I was thinking that it would also be a good idea to apply it all the way up the walls in the spa shower area?? Surely the villaboard needs some sort of waterproofing behind the shower tiles?
.
Not necessary, just need w/p 300mm up from the floor, 100-150mm in from each corner and 1800 high and over each fastener- you did nail/screw the sheets to be tiled didn't you - not glued? :) Don't do the whole wall, the tiles will only be as strong as the w/p membrane adhesion. Re the question about the villaboard lip, you might be interpreting the figure from hardies incorrectly. I see on my literature that the cutaway shows flashing, but it is the vertical corner flashing. You just need to lap the board over the spa and leave 10mm gap for sealer to prevent wicking. I would recommend not using silicone to zip up the wall-wall and wall- floor junctions - use sikaflex - that's straight from the w/proofer I use. silicone does not like to be painted over with things like water based paint and w/p - you don't want to compromise the seal. Do yourself a favour and get a professional - they are cheap relatively.

Cheers
Michael

[JamesD]

Thanks so much for the info mic-d and carpenter; has answered all of my questions.

I know I should get in a pro to do it, but, well, you know...

Cheers
James

[JamesD]

Mic-d, Just one more question!!!



With regard to the sikaflex, should I use that for the horizontal spa to villaboard trims as well or should I use silicon for that seal.

Cheers
James

[Carpenter]

I reckon just go the Sikens, tis much better in all regards than the silicon for this situation. With regards to waterproofing the whole surface, its not a bad idea because the Villaboard is porous & I have seen instances of fungal decay from moisture transmission through it, however as I mentioned before my waterproofer uses a fibrglass system. He coats the wall with the resin (which seals it) then throws fine sand on it whilst wet to provide adhesion for the tiles. The fibreglass sets hard & leaves a very grippy surface, but this is not so with acrylic. The acrylic is much more elastic than fibrglass & I don't think it would work the same way ; a downfall of using acrylic.

[JamesD]

I have placed the villaboard over the lip but it is actually touching the spa itself, ie, there is no 10mm gap to prevent wicking. Is it important that I cut back the villaboard 10mm? Wicking is stopping water from dragging up through it, isn't it?

[mic-d]

I have placed the villaboard over the lip but it is actually touching the spa itself, ie, there is no 10mm gap to prevent wicking. Is it important that I cut back the villaboard 10mm? Wicking is stopping water from dragging up through it, isn't it?
Yep cut it back so you can put a bead of sealer in, 10mm is just a guide. Wicking is the capillary action that draws moisture upwards into the board.
Cheers
Michael

[mic-d]

Just to clarify what I mean by touching. The villaboard can touch the vertical part of the lip but must be clear of the horizontal part, OK?
Cheers
Michael
Oh and I also forgot to mention w/p 300 wide across any joints between the villaboards. And also do yourself a favour and set any joints before you tile just into where the tile line will be. Top coat and sand too. Much easier esp. in corners than after the tiling is done.

[mic-d]

I have placed the villaboard over the lip but it is actually touching the spa itself, ie, there is no 10mm gap to prevent wicking. Is it important that I cut back the villaboard 10mm? Wicking is stopping water from dragging up through it, isn't it?
Yep cut it back so you can put a bead of sealer in, 10mm is just a guide. Wicking is the capillary action that draws moisture upwards into the board.
Cheers
Michael

[JamesD]

And also do yourself a favour and set any joints before you tile just into where the tile line will be. ... Much easier esp. in corners than after the tiling is done.
I don't really understand what this means, is it that I should plaster the joins and corners before I tile?

[mic-d]

I don't really understand what this means, is it that I should plaster the joins and corners before I tile?
Yes, set means base coat, tape and top coat the joints. Just to within the line for tiling. It's a pain in the bottom doing this after tiling.
Cheers
Michael

[JamesD]

Thanks Mic, will do.

I have cut the villaboard back 10mm or so, that was fun...

There is now a sort of little cavity say 7mm under and behind the villaboard. I set the horizontal noggins at about 120mm above the base of the spa line, don't ask me why. One problem that this may cause though is that I will be unable to adhere the Sikaflex to anything behind, if you know what I mean. I will have to carefully fill the space so that the sikaflex sits in the curve of the lip up to the base of the villaboard, but with nothing behind it.

Do you think that is a problem waiting to happen? I thought about taking about 330mm of the villaboard (up to the next noggin up the wall) and then putting some noggins in right down at the lip, then replacing the board and w/ping the cut line. Do you think that is a good move or think it is ok just to leave it. I guess if the Sikaflex adheres well to the spa lip and the villaboard it would be ok?, not sure though as I don't know what the holding and flexi capabilities of Sikaflex are though.

Any thoughts you could offer would be great, then with a bit of luck I think it will be plane sailing from there.

Yep. Plaaane sailing, I'm sure.

Cheers James

[mic-d]

Thanks Mic, will do.

I have cut the villaboard back 10mm or so, that was fun...

There is now a sort of little cavity say 7mm under and behind the villaboard. I set the horizontal noggins at about 120mm above the base of the spa line, don't ask me why. One problem that this may cause though is that I will be unable to adhere the Sikaflex to anything behind, if you know what I mean. I will have to carefully fill the space so that the sikaflex sits in the curve of the lip up to the base of the villaboard, but with nothing behind it.

Do you think that is a problem waiting to happen? I thought about taking about 330mm of the villaboard (up to the next noggin up the wall) and then putting some noggins in right down at the lip, then replacing the board and w/ping the cut line. Do you think that is a good move or think it is ok just to leave it. I guess if the Sikaflex adheres well to the spa lip and the villaboard it would be ok?, not sure though as I don't know what the holding and flexi capabilities of Sikaflex are though.

Any thoughts you could offer would be great, then with a bit of luck I think it will be plane sailing from there.

Yep. Plaaane sailing, I'm sure.

Cheers James
Hmmm, nothing behind it? doesn't the spa lip have a vertical section that the villaboard laps over? Either just cut the nozzle quite wide to give a big bead of sikaflex and/or you can buy foam packing rods from places like bunnies to fill cavities like that, then sikaflex. Its not for aesthetics so fill er up. You will have a second bite of the cherry when you tile, leave a gap between the bottom tile and the spa and silicone it, don't grout it.

cheers
Michael

[JamesD]

Will take your advice and pack the hole up. There is a vertical lip on the spa, just wasn't sure if that alone and the villaboard, which is about 10mm out from it would have been enough. I guess the packing will be good insurance. The wall cavity is still exposed under the spa so I can shove stuff up there to pack it out. Like you said, no asthetics required back there, which is probably a good thing!!

Many thanks for your help