membrane tanking - how much thickness does it add?

[Albumen]

It's a bathroom with overshower bath. Will be tiled.

I want to tank it round the bath with a memebrane based product, probably Homelux but will investigate what's available and reccomended.

What sort of a 'lip' will be left where the tanking ends? Reason I ask is the whole wall will be tiled, but I was only planning to tank the bath area. Will the lip be small enough to lose in the tiling, or should I tank the whole walls. Which will be a pain, as both walls have windows, one has a toilet etc, etc.

Instructions here http://www.homelux.co.uk/downloads/WaterproofMatting_FittingInstructions.pdf suggest a 5mm trowel.

So I assume it's about whatever the adhesive ends up when it's flattened, plus the thickness of the membrane itself. And double that at joints.

So I'm guessing about 3 or 4 mm, but would like to hear from somebody who's done it.

Many thanks, Mike

 

[Richard C]

What base are you tiling onto?
Have you considered this:
http://www.bal-adhesives.co.uk/products/wp1-coating
Or the slightly cheaper Dunlop equivalent (they are the same company now)

 

[Albumen]

New sand and cement. But cracked already!! I didn't do it, a 'professional' did.

 

[PaulEamomm]

I think you're possibly going a bit OTT with the tanking. Provided you use a half decent adhesive (no it doesn't have to be one of the over priced and under performing 'waterproof' ones) and a good grout (I'd recommend BAL Wall - it's suitable for swimming pools and it's easy to use) then you shouldn't need to tank it.

You do, however, need to ensure that the cracks in the render aren't the result of excessive shrinkage which may mean that the new coat is now 'live'. If it is you'll need to chop it off and start again as no amount of tanking, adhesive or prayers will make it a good job.

Hope this helps.

Regards

Paul Eamonn.

 

[Albumen]

Thanks.

I always go what other people go OTT when I do my own work. They're taking me out of this house in a box. In 50 years time I want my son to be lying in my £1000 bath (!) saying to himself - 'Dad made a really good job of this bathroom'.

For the work that's involved in tanking it's a no brainer. I don't do belt and braces. I do belt, braces, another belt, some more braces!!

Actually had a chance to look at the 'sample' display of Homelux Floor membrane in Topps. I think the floor version is a bit thicker than the wall and even that added hardly any thickness. It looks to me like the lip it leaves will be very easy to lose in the tiling adhesive.

 

[Richard C]

I go with Paul; you don't need to tank but if it's "no brainer" & makes you feel better

 

[Albumen]

Hope it didn't sound rude me saying it was a 'no brainer'. Didn't mean to come across like that.

I just meant that it seems straightforward to do the tanking (though I've not actually done it yet of course), so I can't do any harm. It looks like about £80 of matting and tape plus the extra adhesive, so about a ton altogether. I'm happy to spend that and do the work to get the best job I can, in terms of water resistance.

The absolute last thing I want is to get to 72 (which is 20 years away) and find that lots of things are failing, along with my health.

Like I say, belt and braces. I'm putting a very high quality bath into this room, looks like we're heading for expensive tiles, I've spent money on tools so that I can do the plumbing to my standard, and the way I want it. I've replaced every board with full length new ones. Screwed too, so the floor is rock solid. I got filthy dirty taking old plaster off, eyes full of crap taking bits of ceiling down, money to lecky for new lights, which then also meant RCBOs, which in turn meant FULL set of RCBOs one for each circuit, which is best in the long run. So £100 to tank it is nothing.

Especially when it's the background. As we all know - 'It's all in the preparation, luv'. e.g. I asked my neighbour to give me a hand getting my new bath upstairs. It's big, steel and heavy. He was admiring my bathroom floor. 'Nice solid new boards'. He had tilers in 'repairing' the bathroom floor tiles they put in 18 months ago. Now he's not a cheapskate I don't think. Certainly not short of money. But because his bathroom boards were rough, uneven, levelled up with hardboard etc, his tiles had, of course, cracked. Because the tilers hadn't done the job properly.

That's not my way. I want the stuff underneath to be as sound as possible, so the stuff on top will stay there and look right. God, I'm going on aren't I?

Apart from the time and cost, is there any potential downside to tanking membrane?

 

[PaulEamomm]

Just make sure that you feather the tiles gradually over three or four (vertical) courses so as the difference in levels won't be seen. The only problem you may have with this is, if you stop the tanking at the end of the bath and the wall past the bath drops to the floor, you will need to build out the tiles all the way both down and up and then possibly cut the bath panel to fit too.

Something else you could do is to continue spreading the adhesive you use to stick up the matting a bit further on so as to do some of the feathering out for you.

Something else I feel I've got to say is that it would seem to me that you are taking on more than you really need to. I've just looked at the link you supplied in your first post and getting the final surface really flat may be beyond some people. As I don't know you plastering skills I may be speaking out of turn here but I would be inclined to consider the BAL tanking system where the glue only needs to be painted on rather than trowelled. It may make things all a bit easier for you. Here's a link -

BAL Tanking

 

[PaulEamomm]

Mike - looks like we cross-posted.

There aren't really any down sides to doing the tanking apart from the money, the work, the mess, trying to get the polymer off you hands etc. Apart from that there's nothing to it. I guess we pro's just don't like to stray from the norm too much. Perhaps my username should be 'Ludite'!!

Let us know how you get on.

 

[Albumen]

Just make sure that you feather the tiles gradually over three or four (vertical) courses so as the difference in levels won't be seen. The only problem you may have with this is, if you stop the tanking at the end of the bath and the wall past the bath drops to the floor, you will need to build out the tiles all the way both down and up and then possibly cut the bath panel to fit too.

Something else you could do is to continue spreading the adhesive you use to stick up the matting a bit further on so as to do some of the feathering out for you.

Something else I feel I've got to say is that it would seem to me that you are taking on more than you really need to. I've just looked at the link you supplied in your first post and getting the final surface really flat may be beyond some people. As I don't know you plastering skills I may be speaking out of turn here but I would be inclined to consider the BAL tanking system where the glue only needs to be painted on rather than trowelled. It may make things all a bit easier for you. Here's a link -

BAL Tanking

Some great suggestions there, thanks Paul.

Yes, I was thinking of finishing the tanking at the bath end. Though looking at how much there is on a roll I might not have enough without buying 2 rolls, so might just do the shower end of the bath. I was thinking I'll put the bath panels in first, then do skirting and tiles up to that, rather than cut the panel round the skirting. No?

Good idea feathering with the under membrane adhesive. If I let that adhesive dry there's no problem with the putting the 'real' tile adhesive on top of it is there? New doesn't reactivate old or anything does it? Assuming it's the same stuff.

My plastering skills? For this I'm confident ish. I laboured for a plasterer for a year or so (a very long time ago), bought a float and hawk and did a bit. I don't do any finish plaster now, cause I can't get a good enough, er, finish. But tools don't feel strange in my hands. So I'm happy to be trowelling tile adhesive on.

 

[tictic]

first of all..just tank around top of bath and corners for belt and braces mate.(50-75mm menbrane strips)..

as for tanking!! if you go for this,then ok ..dura wp/ditra/homelux.

and when you apply this,there wont be any lipping!!..as you will aplly this with a 5/6mm notched trowel,then using the smooth side of trowel, smooth the matting(just like hanging wallparer)...2-3mm thick at most....then when you apply tiles to walls...using a larger rib/combed..trowel THERE will be no lippage.(back butter tiles as well)..

as for the paint on "version"..you will apply this with a smooth trowel,then leave 24hrs before tile fixing.but if you aint got the right thickness/coverage,then you cant apally a 2nd coat...

check render..why is here cracks?..then tank bath edge/corners...job done..

 

[PaulEamomm]

You shouldn't have any problem with the tile adhesive and the tanking reacting. They are, after all, supposed to work together.

As for fitting the bath panels first this, IMHO is a real No, No! And depending upon the type of situation you've got and panels you're using, the no's increase exponentially.

If you've got the plastic panels you'll need to cut around them which can look scruffy. Problem then is, if you need to cut them you'll be cutting away the lip that gives the panel its rigidity. There is also the removal aspect at a later date to consider. If you tile them in place you may not be able to remove them should you need to without cracking them.

If you're using a wooden type panel then tiling to them isn't such a chore but getting them out can be an issue.

It's something you need to consider the implications of before you commit yourself.

As regards the skirting, if you need to build out the tiles to get over the tanking you may lose the top edge of the skirting under the built out tile. It may even be that you'll find the tile is proud of the skirting top. This can also be a problem if you are coving between the wall and the ceiling.

As far as I'm concerned, it is far better to tile down to within an inch or two of the floor and then stick the skirting to the tiles with gripfil. Doing this looks much better and only potentially becomes a problem if you need to marry the skirting up with architrave. Depending upon your carpentry skills you may be able to angle the skirting into the architrave.