[Irfan]

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?

[nealtw]

Haven't seen straw board. Is the wall made out of straw or are these sheets over a stud wall?

[inspectorD]

Is this a straw bale home and you are on the inside of an outside wall?
If so ,I would build a 4 inch block wall over the face of the straw wall, if you have the room, then coat it with a tile waterproofer http://www.laticrete.com/architects/products/waterproofing.aspxand tile over that.http://www.schluter.com/8_4_kerdi_shower_kit.aspx
Or go with something that will last a while, but pricey

[Irfan]

Straw Wall is also an old building method made into new with some added science. The panels are made of rice straw and hulls that are highly compressed with a custom-designed machine. Steel mesh (made of 100% recycled steel) is layered on either side of the panel keep the straw compressed. The straw is a natural insulator, so no additional insulation is needed for construction, and the panels can be covered in plaster, sheet rock or siding.

[nealtw]

There is other posts here talking about killing mold with a borax product, after that I would cover it with backer board and the shluter in Inspectors post. If you can plaster this stuff and it is in good shape maybe you could leave out the backer board.

[Irfan]

Yes i think this is a good way and i can avoid extra expenditures.