What is this on my wall?

[dparry]

Hi,
Quick question, I have just taken all tiles off the wall and it has taken all the pink skim off with it, under neath is a sound and solid base, it seems to be a "grey" colour and seems cement based.... it is solid to knock... but if I scrape it it comes off like dust fairly easy.... what is it? it doesnt seem to be a sand base?!!

Can I tile onto it direct with mapei keraquick adhesive? would I need to prime, or am I better off getting it reskimmed and the tile over?

Thanks for the replies

DP:mad2:

 

[Alan.P]

Hi DP.

By the sound of it you have pulled off the skim plaster coat and revealed the backing plaster. If it is as flakey as you say you may be better off taking it back to brick and either dot and dab plasterboard onto the block or get it re-plastered, first option being the stronger to tile to.

What amount of wall space are you talking of, is it viable to do ? and what size and type tile ?

And it's not ideal to fix to backing plaster, even primed as it would have to be anyway, yours sounds as if it has to be removed and or made good.

Hope that helps a bit for now.

 

[dparry]

Hi, Yes the wall isnt flaky its just "sandy " I guess, the backing is solid and thereofre requires a skim to flatten and provide a key to lay tiles on?

The room is a small bathroom 2m x 2m, and have taken tiles off all 4 walls two walls came off right back to the brick, have since dot and dabbed these 2 walls with plasterboard (they were internal walls) and the backing coat was totally shot.

The other two external walls have a much stronger backing coat on it, and would be difficult to get off, I am hoping to get it skimmed and made good again?

Here`s the catch I am planning on tiling travertine tiles 300x600mm on these 4 walls wall to ceiling, I know that the drywall is meant to be stronger but can you tile plastered walls with these?

Thanks

 

[david campbell]

wouldn't recommend it mate,plaster skim only holds about 20kg per m2 and i'm pretty sure the travertine will weigh more than that when you add on 5kg per m2 for adhesive and grout,so you will be left with 15kg per m2 of tiles! best bet is to place a m2 of tiles onto the bathroom scales!

 

[Alan.P]

Hi DP.
As David says, with the weight of tile you fixing it really would need to be on a substrate other than plaster. Here is a guide to weights and substrates etc

LINK

Let us know what you decide or for any further help just shout

 

[Ajax123]

Hi,
Quick question, I have just taken all tiles off the wall and it has taken all the pink skim off with it, under neath is a sound and solid base, it seems to be a "grey" colour and seems cement based.... it is solid to knock... but if I scrape it it comes off like dust fairly easy.... what is it? it doesnt seem to be a sand base?!!

Can I tile onto it direct with mapei keraquick adhesive? would I need to prime, or am I better off getting it reskimmed and the tile over?

Thanks for the replies

DP:mad2:

Could be thermalite or aircrete blocks. If you chip out a small piece it will look a bit like an aero bar...You can multifinish straight onto primed aircrete although it is not generally done it would normally be dot and dabbed plasterboard. Not sure about tiling straight onto it though.

 

[White Room]

If the skim coat has come off and the backing sound like sand/cement, I would tap the wall to see if there any hollow areas, if sound try to scrape the remaining skim off and prime with sbr at 4-1 so it soaks in and binds any dust in the sand/cement surface. IMO

 

[dparry]

Thanks for all your comments, I have now taken the render off back to the breeze block/brick surface, I am now going to dot and dab standard plaster board to all 4 walls...

Do I now need to water proof this, my prefered manufacturer is mapei, as I have bought kera quick adhesive to put my travertine stone tiles up.

Do I first prime the plasterboard with primer g?

Do I then use mapegum wps to water proof...

and then use the keraquick to put the tiles on... will it all work together ok? its not for a wetroom justa bathroom with an over bath shower! do i need to waterproof the whole bathroom i.e. all the plasterboard?

many thanks for your advise

Dylan

 

[Dan]

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