Re-using Marmox

[John.Stitch]

I had to remove tiles from my shower as a leak on the outlet pipe caused water to drain down the walls between the tiles and the Marmox to the tray and over the upstand.
In removing tiles to find the leak I was able to pull tiles off wetted areas easily but other areas I have damaged the Marmox.

http://img35.imageshack.us/img35/8026/p1000413z.jpg

Not sure if I can scrape or sand the old adhesive off or if I wetted it then the adhesive would come off more easily.

The damaged areas of Marmox I am not sure about, whether I can fill them with adhesive and sand or to replace?

The blue area is on an external wall and so the Marmox is glued (dabbed) straight onto the wall so would be easier to replace than onto studding on the other wall.
Another smaller area is to the right of the valve which is not clear on the picture.
The water got into the corner of the wall on its way down so not sure if the sealing there needs replacing or going over again with silicon?

To replace the Marmox the problem I will encounter if I remove more tiles is the damage to the wall as I need a good section of board to butt the new piece to to then seal over.

 

[Richard C]

If it’s a decent waterproof adhesive wetting shouldn’t make much difference, what may happen is you start to pull more of the surface of the Marmox away with it. If on the other hand its crap DIY addy that’s another matter.

Don’t use adhesive & sand to fill, presumably you’re thinking tub ready mix, I wouldn’t use that. If the Marmox is still basically sound & hasn’t started to crumble you could level it off with a powder cement based adhesive. What size are those tiles? Anything over 250 x 250 mm & you should really start thinking about using flexible powder addy anyway.

Marmox boards should be installed on a continuous adhesive bed, not just dot & dabbed & I even use additional mechanical fixings; don’t forget the board is supporting the weight of the tiles!

Problem with using silicone to seal the boards before tiling is that not much sticks to it, including adhesive & grout so you could make matters worse, it should be tapped.

 

[John.Stitch]

Thanks Richard, I was hoping you would advise.
The tiles are 333x253.

Small sections of the Marmox have been removed the blue filling to the surface on the other side, so it is pretty deep in places.
I may replace that section.

I have a small amount of tub adhesive left over which I could have used to fill but as I need to get some more I will do as you suggest and use the powder flexible adhesive.

I may remove one sheet of the Marmox around the valve and below it to reinforce the studding behind it as the Marmox moves when you push it.
The studding is 400 cts vertically but noggins are at 1 metre approx.

Thanks for the tip on the Silicon, I have some tape.