Insulating and waterproofing external bathroom wall

[collapse-sued-turkey]

Hi all,

We have stripped our bathroom walls back to brick and are lining them with NoMorePly fibre cement boards. The reason we went for cement boards was for the moisture resistance and for supporting the large-format tiles we’re planning (90 x 90 cm).

The tricky part is the exterior wall. This wall has the following complications:

• Has a window
• Has a heavy basin mounted on it
• There are water pipes close to the wall (about 50mm distance from the brick
• The bottom half of it will be tiled, and the top half just painted

We want to ideally insulate this wall, while also making it as moisture-resistant as possible and being able to hold large tiles.

Our current plan is to use 40mm Thermaline insulated plasterboard on that wall and inside the window reveal, cutting around the pipes as needed and filling with expanding foam before putting the tiles over.

Would this be the right approach, or is there a better way to handle insulation and tiling on that wall? Is there such a thing as fibre cement insulated board?

 

[Deluks]

Marmox multiboard, available in a variety of thicknesses.
If you put heavy tiles on it be sure to use adhesive and the proper fixings. Basically follow manufacturers instructions.

 

[mikeey84]

As above, I did Marmox 40mm. It's not quite as good as PIR insulation, but much better than nothing.

Dot and dabbed to wall with tile adhesive, then fixings drilled through dabs (as per installation instructions)

Easy to cut with an old saw.

I'd repipe rather than foaming, but it's a lot more work- will help prevent condensation.