Internal/external flashing?

Hi All,

I've justin been flicking through the James Hardie wet area construction guide and am curious about people preferences and ideas about internal and external flashing. I couldn't see a clear reason for prefering either from the guide. I was going to go for internal(I think it'll be ok, though they don't show an example with floor boards, firbro-cement then tile floor) because it meant I wouldn't have to put in additional noggins, so less work. Is there a particular reason for using either?

Stoo

Have just done 3 bathrooms, two toilets and two laundries. In NSW you have to waterproof the whole floor and 6" up the walls all round, plus any splashbacks and behind the shower if you are tiling it. Because of this, it's pointless putting internal flashings behind the wall sheets. We paid a waterproofer to do the job and he used a flashing tape on all joints and penetrations then painted a membrane (thick green stuff) all over the area.

Thanks for the info silentC.

If I was to go down that path. Would it just mean I would put up the wall sheets(leaving a small gap at the bottom) and lay the floor sheets. Get someone in to waterproof it then just tile/grout and seal it up?

Stoo

Put your flooring down first, then hang your wall sheet. The wall sheets can stop half an inch or so up from the floor. You'll need to joint the corners and any other joins that occur where the waterproofing needs to be done first. I got the plasterers in to finish the job before the waterproofer/tiler came onto the job.

Next, the waterproofer came in and flashed the floor/wall joint all the way around the room. He flashed around the floor waste and the other floor penetrations and any wall penetrations that were within the area to be waterproofed. They use an adhesive flashing tape for this. Then he used a roller and a brush to paint on the membrane around the room, covering the whole floor, 6" or so up the wall all the way around, behind all the splash backs and 1500 up the wall behind the shower.

Regs could be different in Vic so you might want to check on that first.