Impervious board

[Rob Graham]

I need some board, akin to MDF, which is either impervious to water or has a facing which is. Could someone suggest a possible product? It needs to be say 1/2" thick, maybe a bit more.

Ta

Rob Graham

[the_constructor]

18mm ply which they use for fencing on building sites. Can't remember the exact name but no doubt someone will

[MuddyMike]

I don't know if its suitable for your needs but I have bought waterproof plasterboard for a shower stud wall. Just in case the tile grouting leaks that was 12mm thick.

Mike

[Rob Graham]

Would that be Knauf Aquapanel Plasterboard 1200X900X12.5MM @ £13.20 a sheet (approx 1 sq metre)?

Rob

[js.b1]

Insulatory would be Marmox. Available in 6mm 10mm 12.5mm 20mm 30mm 40mm 50mm 60mm. The core is eXtruded PolyStyrene (XPS) not expanded, with cement facing & glass fibre reinforcement. Very light, used for wet room floors, walls, etc.

Non-insulatory would be Knauf cement panel. Very heavy, you can leave it under water a few years and it does not care.

If this is for a bathroom, the insulation value can be useful, but you need to use a waterproof grout, waterproof (cement) tile cement, and waterproof cement (Mapei Keraflex) to stick the Marmox to the wall and glass fibre scrim tape the joints (like plasterboard) and polyurethane sealant the joints likewise.

For wet areas do not use plasterboard, it goes to mush especially if you have a solid brick wall in an exposed location.

[MuddyMike]

Sorry I don't remember the brand. I bought it from Jewson and it was about 3 times the price of normal plasterboard.

Mike

[Bob Minchin]

Mike,

My shower has suffered from grout leaks (after a good few years of use). Made from standard plasterboard and tiles with waterproof adhesive and grout. The effect of the leaks has been that water had soaked into the tiles from the back and discoloured some of them behind the glaze (but not all grrr!). The integrity of the wall is fine.

I think what has happened is that the waterproof adhesive has worked to seal the wall but the tiles are still wrecked.

So whilst there is no harm in using your waterproof board, you might not get the protection you are hoping for against grout leaks.

I'm not looking forward to sorting mine out as the tiles are on three out of 4 walls of the bathroom and naturally are no longer available!

Bob

[Rob Graham]

Thanks for all your help here. In fact. I'm able to get melamine-faced chipboard quite easily, and not a lot of money.

Rob