Plastering concrete ceiling

[Biglou]

Hello to all, hope im not posting to many topics on here to be deemed over enthusiastic!

My mate lives in a flat and the whole ceiling was covered in like horrible polestyrene things all over it, all glued on.

I was wondering what would be the best course of action to take to re-plaster a concrete ceiling would be?

Strip off ALL the horrible old polestyrene stuff. (i mean every last bit)

Then mix up some pva with abit of sand in it and pva the whole thing and leave for 24 hours? The ceiling is smooth and flat so would this sand in the pva give it enough of a key to stay up there?

Or would a spatterdash coat of sand/cement/pva be the order of the day?

And then re skim with multi finish? Ive already read that you can re-skim right onto render, so im assuming this applys for a ceiling aswell? Only gravity has a much bigger pull on a ceiling! So i dont want to risk anything!

OR would it be better to batton out the ceiling and then plasterboard it?

As you may imagine im trying to just improve my knowledge of backrounds and things like that ect, as that is where you never stop learning!

Any advice would be very helpfull and very much appriciated. Has anyone come across this situation before (im sure they have).
What would you do?

Thanks again everyone.

Lou.

 

[roughcaster]

It's not a problem plastering onto a concrete ceiling. You would have to make sure all the remnants of polystyrene, glue etc were removed, as you said. After the prep, give the ceiling a PVA,, then a couple of tight coats of bonding coat plaster, "while the pva is still tacky",, let it set up, then 2 coats of multi. I repeat again though Lou,, use bonding coat plaster first,, then multi finish,,, and keep making sure the pva is not drying out as you spread onto it.
We plastered over many a poured, mass concrete ceiling when i worked for firms at the local RAF base,,, did them all the way i mentioned above,,, cement rendered a lot of them as well.

 

[Biglou]

Hi roughcaster, many thanks for your helpfull reply.

Thats really usefull advice . Bonding, then finish.

So if it was already cement rendered and not concrete, would you be able to skim directly onto the cement render?

Or is it always best to do give it a coat of bonding first so its really tough?

Thanks very much, ive read alot of your other posts aswell R/C. You are very experienced.

 

[roughcaster]

You can skim directly onto un-painted cement render without any problem at all, depending on ability. If it was painted render, you would need to prep/pva it first.

Bonding coat is ideal for plastering onto any prepped/pva'd concrete surface/ lintels, etc. The reason for the bonding coat first, then the multi is, it's a prepared surface, an undercoat for the multi finish. If there are any bad or uneven areas/joints in the concrete ceiling itself, multi on it's own would not be a good idea,, whereas bonding first, preps the ceiling/wall for the multi. I never plaster/skim any wall/ceiling without using bonding coat first,, then multi.

 

[Biglou]

Thanks roughcaster.

You information is priceless.

 

[Nige F]

It's not a problem plastering onto a concrete ceiling. We plastered over many a poured, mass concrete ceiling when i worked for firms at the local RAF base,,, l.

Typical Brylcreme Boys wanting plastered bunkers