6" waterproof adhesive membrane tape for niches in shower wall. (2025)

Hi all,

I realise that there may be quite a few sore heads out there today, so I am not expecting quick replies. I am hoping to find some (a lot of) help. A false wall has been constructed in my bathroom and two niches have been put into it. The 'wall' has been boarded over with aquapanel cement board and the niches have been constructed with similar. I need to tile the entire bathroom now, but taking it one step at a time, I need to waterproof the niches and also cover the screws and the one corner that meets an outside wall. Having watched many YouTube vids, the way to go seems to be 6" membrane tape, further sealed with a tanking product. Unfortunately, all the videos used 6" tape, but they were all US videos and I can't find any 6" tape here. I have tried a couple of Plumbing suppliers, but they didn't do anything like that.

My niches have a depth of almost 4.5 inchs and the widest I can find is approx 5" which is not enough to suitably cover the inside and the outside edge in one go, which means I might have to overlap two pieces. If I am going to do this, I have some memeasy 3" tape, would I be able to use this instead please. I am aware that there are 'tanking kits' on the market comprising of sealer, tape and tanking membrane. Unfortunately, the ones I have looked at, the tape is not wide enough, the Aquaseal one is only 2" wide. Is it totally necessary to use sealant before the tanking membrane?

Beyond that, can anybody recommend a decent tanking solution at a reasonable price please? They all seem extortionate and I am doing the bathroom on a budget.

I have attached a picture of the niches. Please be kind I am almost a beginner. I am very happy to have differing views.

Not sure if I have done this right, but here goes. Many thanks.

Many thanks for your replies. I have had a look at the Dunlop tanking kit, which seems quite expensive (I thought Selco was supposed to be cheaper!). Does anybody not recommend Everbuild Aquaseal, which seems a bit cheaper?

The wall that adjoins the cement boarded wall is an outside wall, does this need to be treated with the tanking solution? Also, does it need to be treated with sealant first? Thanks.

The Kits all seem to be £50-£70.
Not something to skimp on in my opinion.

I did my Corner Shower with Foam Filled Waterproof Board, taping the Joints, Screws and Corners.
Tanked the entire area.
I would just tank the Area that is likely to get splashed from the Shower/Bath.

tillybud said:

Many thanks for your replies. I have had a look at the Dunlop tanking kit, which seems quite expensive (I thought Selco was supposed to be cheaper!). Does anybody not recommend Everbuild Aquaseal, which seems a bit cheaper?

The wall that adjoins the cement boarded wall is an outside wall, does this need to be treated with the tanking solution? Also, does it need to be treated with sealant first? Thanks.

Click to expand...

Assuming you mean primer when you say sealant then yes it absolutely needs priming before taping and tanking, if I'm not using a kit then I just use diluted SBR rather than a specialised primer although you get a primer in the kits, you need to tank on both of the shower walls.

I'd also recommend using polymer mastic down the corner before taping and tanking, timber frame to solid wall transitions are always vulnerable due to possible movement of the timber.

Thanks McSport and Ceebee. I wouldn't have thought about the timber frame to solid wall and I will make sure I add that to the jobs. By the time I have bought everything, I think it will probably be cheaper to buy the kit.

I know at least two tanking coats are recommended and most kits seem to be 5kg. Not sure how far that will go so I will keep it in mind to concentrate the tanking where the shower reaches. Good idea.