Plastering on to 1930s cinder block

[sarahjane 10]

Does anyone on here have experience of plastering on to 1930s cinder block (internal wall).

I am renovating my bathroom and when taking off the old tiles it pulled off some of the underlying plaster and also what I think is sand cement render (or possibly browning) from the orginal, crumbly, cinder block.

I had the holes filled in and the walls skimmed but when I tried to tile it pulled off the new skim (which hasn't adhered to the original s/c rener (or browning) and pulled off the s/c (or browning).

I have tried a number of tests with tiles on the various surfaces I now have on the wall since and nothing is working.

I think I am going to have to remove everything back to cinder block and wondered if anyone had any experience of platering on to this stuff and could tell me the best plaster to have put on to it.

I believe spraying the blocks with water then applying thistle hard all plaster, follwed by a skim of the multi finish might be the best bet, buit am nervous about the level of suction of the blocks.

 

For information: plaster boading or aqua boarding is not an option as: (a) there isn't enough room - i ony have a 71cm space and the bath is 70cm wide, and (b) the cinderbock can not be screwed in to.

 

Any thoughts?

Oh and the tiles weigh 16kg per sqm, just for info.

Thanks

Sarah

Edited August 17, 2012 by sarahjane

[handypandy 14]

Was the wall given a minimum of two coats of PVA prior to the filling & skimming ?

 

Also, may be best to try a powder tile adhesive and mix it yourself, rather than the tubs of ready mixed as it does tend to have more suction.

Edited August 18, 2012 by handypandy

[spider1 11]

Was the wall given a minimum of two coats of PVA prior to the filling & skimming ?

 

Also, may be best to try a powder tile adhesive and mix it yourself, rather than the tubs of ready mixed as it does tend to have more suction.

 

Yes the wall should have had a couple off coats of pva prior to skim . Try getting skim off if its loose and make sure sand and cement is firm on wall . If not take that off and give wall 2 coats of pva prior to re plaster.

[spider1 11]

Was the wall given a minimum of two coats of PVA prior to the filling & skimming ?

 

Also, may be best to try a powder tile adhesive and mix it yourself, rather than the tubs of ready mixed as it does tend to have more suction.

 

If skim is loose it will have to come off no other way. Then make sure sand and cement is stuck solid on wall if not this will have to come off. Same as handy pandy says all surfaces will have to have 2 coats of pva prior to re plaster and skim. Tiles are to expensive to buy and put on to mess about with. Why not have a look at alternative to tiles now on market. Dont like them myslf but i am old fashioned . Same procedure would have to be followed regardind plaster. Good luck.

[sarahjane 10]

Hi

Yes, the wall had two costs of pva before it was skimmed.

Were the skim was loose it is now off.

I now have some bits of wall down to cinder block, some with s/c render (or browning, not sure) on (although its very dusty/sandy) and some with the original plaster on from years ago.

I think the sand cement is going to have to come off completely, but am nervous about what will actually hold to the cinder block as that itself seems so fragile.

Some people have said don't pva on to cinder clock, just spray with water the use hardwall plaster, and some are saying pva then plaster.

Just not sure and can't stand to waste too much more money.

 

I did buy bagged adhesive for the tiles....in fact i've done the test tiles with both tubbed and bagged. The other problem I am having is that the bagged stuff isn't sticking to the back of the tiles.

 

It seems to be one problem on top of another.

Sarah

[spider1 11]

Hi

Yes, the wall had two costs of pva before it was skimmed.

Were the skim was loose it is now off.

I now have some bits of wall down to cinder block, some with s/c render (or browning, not sure) on (although its very dusty/sandy) and some with the original plaster on from years ago.

I think the sand cement is going to have to come off completely, but am nervous about what will actually hold to the cinder block as that itself seems so fragile.

Some people have said don't pva on to cinder clock, just spray with water the use hardwall plaster, and some are saying pva then plaster.

Just not sure and can't stand to waste too much more money.

 

I did buy bagged adhesive for the tiles....in fact i've done the test tiles with both tubbed and bagged. The other problem I am having is that the bagged stuff isn't sticking to the back of the tiles.

 

It seems to be one problem on top of another.

Sarah

 

Seems like you are going to have to take it right back to original . Dont know any thing browning wont stick to. Ask a bulder for a quote for to sort prob out . If wall is unstable it may latting and plaster boarding.

[sarahjane 10]

Thanks Spider1.

Browning is something else I thought of too.

It's so frustrating.

So far I have spent money on having it plastered in the first place, and waster money on three types of adhesive, lost £60 of tiles and months of work.

The whole thing is starting to send me mad!

Sarah

[spider1 11]

Thanks Spider1.

Browning is something else I thought of too.

It's so frustrating.

So far I have spent money on having it plastered in the first place, and waster money on three types of adhesive, lost £60 of tiles and months of work.

The whole thing is starting to send me mad!

Sarah

 

Crikey this should should not be a complecated job. Dont suppose its worth while you getting plastrerer back as he sounds usless but you could try. Tell him skim is coming off see what he says . You did let skim dry before you started tiling didnt you.[ goes white]

Edited August 18, 2012 by spider1

[retired 10]

PVA it and try using Thistle Bonding as a backing coat. Sticky as hell and a dog to use but works. Skim with finish.

 

Sand and cement is what tilers used in the old days but with no skimming, just slightly keyed. To strong for direct application onto your blocks.

[sarahjane 10]

I've had the plasterer back. He says it isn't worth skimming again as it will just come back off.

He says he can do whatever i want him to do but I don't even know what to ask for which is why I'm asking on here.

It's a right performance.

Once person told me I might as well take the whole wall out and build a new one!

 

The skim wal left for 4 weeks before i started tiling on to it.

[Mayfield 10]

Have you had an asbestos report carried out as asbestos use to be mixed with plaster?

[sarahjane 10]

No asbestos report but there isn't any original plaster on. It's a sort of sand cement or lime stuff.