I've just got a job tiling 2 new bathrooms. I've now noticed that there's no polythene behind the Hardibacker over the shower tray and bath in either bathroom. I'm not supplying any materials on this one and will be using Granfix multifix and maxigrout for 400x250 8mm ceramics with a 75mm glass mosaic dado.

The baths and shower trays have been siliconed against the Hardibacker boarding on studwork. I always pre-scrim the Hardibacker joints with adhesive but I always also put dpm behind the boarding with a wide dpc on the internal angles. Should I insist they take the boarding off and do the same or am I being OTT?
The job is due to start towards the end of next week.

I'll leave that with you while I go out for a ruby.

Pete

Hi Pete

I've not put dpm behind the boarding before, is it a dormer loft conversion if so it may need a vapour barrier depending on how it is constructed.


might just be a little ott as you say.

Gary

Thanks Gary

Sorry for the delay in replying. I've been unblocking some drains we share with our neighbour. On a Sunday!! Has nothing to do with last night's curry I assure you!

I've finally found my Hardiebacker data sheet and it says 'When Hardiebacker cement board is installed behind showers you should install a PVC membrane sheet to assist in the prevention of water ingress. Corners of walls and penetrations should be flashed with a PVC flashing or similar'. Mind you it also says that the sheets are easily cut which I definitely don't agree with.

This isn't a 'I told you so' moment, I just wanted to know what general practise was. This builder I'm working for seems to think that tilers just tile, that they don't do the prep work. The next room I'm going to have to tile is a wet room (in the same house) and it sounds like the builder intends tanking it himself. I like the Weber system best. I don't know how he's going to do it yet but I've always tanked my own wet rooms before tiling. I can't see how I can guarantee anything if I haven't done the prep work.

Pete

That's why i tend to stick to Marmox board as it is actually waterproof and doesnt let water or moisture pass in either direction, i only use hardibacker 250 6mm on floors.

But as you say if the builder wants a gaurantee then you have to prep everything yourself in my opinion.

That way you know is has been done and done correctly.