backerboard and extra noggings/taped joints vs tanked plasterboard

[SJRSJR]

I'm renovating a bathroom and have ground to a halt on the way forward. Two walls are stud walls with noggings for normal size plasterboard, two are external cavity walls with a plaster scratch coat.

I had in mind to use waterproof backerboard on the areas that would have direct contact with water, and moisture resistant plasterboard on the rest (which will be part tiled, part painted).

As the backerboard size is 1200 x 600 it'll mean extra noggings on the stud walls and more taped joints. It's a decent sized room and with other work on the go, the cost is mounting up.

Meanwhile my mate is saying to use ordinary plasterboard and just tank the wet areas. Is that a false economy?

 

[simplesteve]

I’ve been fitting bathrooms for years, using both p.board and backers, depending on customer instructions. When the choice is left to me, and in my own bathroom, I’ve used Plasterboard. It’s cheaper, it’s faster, there’s less joins and if it’s tanked and tiled and grouted and siliconed properly, then there are no “areas that would have direct contact with water”.
In summary, if it’s all done properly:- plasterboard all day long.

 

[SJRSJR]

Thanks simplesteve. I've just been tallying up. The cost of the tape is as much as the board so I'm inclined to do your way. I could go with moisture resistant plasterboard but I'd also like to insulate the external walls. The PIR board had a foil surface - is there a way to stick p/b to it without battening?

 

[Jahjahbinks]

Thanks simplesteve. I've just been tallying up. The cost of the tape is as much as the board so I'm inclined to do your way. I could go with moisture resistant plasterboard but I'd also like to insulate the external walls. The PIR board had a foil surface - is there a way to stick p/b to it without battening?

idk if it's too late but just because someone has been doing something a certain way doesn't mean it's right. Get a large backerboard and use that in your wet areas. moisture resistant in other areas. I may have messed up myself as tanking now is reg and I thought taping my boards and sealing would suffice.

 

[SJRSJR]

Thanks Jahjahbinks.

I’ve done exactly as you said - Marmox backerboard in the wet areas and m/r plasterboard everywhere else. I’m not finished yet but I’ll have to look into Regs as Marmox say their boards are waterproof and only need taping/sealing.