I have finally started with destroying my old bathroom and now I have found this straw wall. I was thinking to tear this down and build new stud wall or to "glue" Tile mate backer board on this straw, which would be the easiest way to do it, but would it be the best way? The black spot in the middle is moulding straw which has been attacked by water penetrating through old tiles. What would you do in my place?
Yes, nasty stuff isn't it? Wait until you try and fix something to it!
I treat each occurrence according to the condition of the straw. Generally in a bathroom there will always be some water damage to the straw, but in most cases, removing the worst then skimming the rest to level the area up generally leaves a suitable finish than can be tiled over.
If there is evidence of water penetration to the other side then maybe the whole wall will need to be replaced, but I have never had to do it yet. So far!
My bathroom walls are also made of straw/strammit board .. I had the same problem after a long term water penetration, over the top edge of the bath. I had quite a bit of black mold which I raked out. This left the straw loose and flakey. The area was dried out using a hair drier, then over a few days I applied quite a few coats of Unibond, which bonded the straw together.
My intention was to cover the existing straw wall with Aquapanels, so as to eliminate any chance of further water damage. My thought was I dont want to do this again, so I got 24 tubes of Gripfil and glued the Aquapanels in place (at least 10 years ago) on the three walls surrounding the bath/shower. This gave a perfect tiling surface, and I can honestly say no cracks have appeared since.
Moisture is not often a problem in straw wall homes as long as the house was built well. That said, there may be issues that show up over time. Here are some basic things to consider when wondering about moisture issues in the home.