Skimming sand and cement render

[noodles]

Hi

Had quite a bit of experience now solid plastering with hardwall and skimming and skimming plasterboard. I have plastered the kitchen walls with sand and cement, in places it needed to be built up significantly approx 1 1/2 inch to get them level and would have been a fortune in hardwall. I did a a 4:1 scratch coat with waterproofer and 5:1 top coat levelled off with a straight edge. The original walls had a bit of penetrating damp.

Anyway a few questions if I may:

1. I levelled off with a straight edge it has left a surface that would give a good key but is slightly dusty now it has dried, should I have closed it in with a float (or devil float) or is this only done on exterior render?

2. As s/c shrinks how long is recommended before I can skim remembering the render is quite thick do i just wait 1mm/day?

3. Obviously the wall surface will be really dry and as said slightly dusty, should I just wet down or treat it like a reskim with 5:1 pva to seal then 3:1 pva and wait to go tacky before skimming?

I am thinking that using pva in this case is incorrect because waterproofer is in scratch coat then the only way moisture can escape is through the surface, but would be unable to because of the pva?

Any help would be really appreciated and thanks in advance

 

[johniosaif]

You should of floated with a devil float, leave for a week to cure before skim. Pva should not be needed, slightly dampen is enough in most cases. You would of been better floating it with the same mix , it becomes one coat anyway unless curing time is allowed between coats I learnt this from essexandy but keep that between us.

 

[spunky]

if you havent used waterproofer in the top coat you want to use pva, treat it like youre doing a reskim over unpainted walls

 

[Mikey2184]

Should of added lime to the mix as well on old buildings helps with the movement and stops as much cracking mix should be 9 sand 2 cement 1 lime and a good half a cup of waterproof .
If your dubbing that much out in sand cement the lime also helps you with the workability of the sand cement .

 

[nickelarse]

you should of asked those questions before you did it!