Skimming over SC render - how long to leave render to dry?

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looky

New Member
Hi, I'v got a couple of walls that I have been advised to sand and cement render to protect against damp.
It is a bit of an ordeal because where I removed two chimney breasts there are 2m wide and 7cm deep recesses, so I need to build out the recess until flush with the rest of the wall and then render the walls.
I want to know how long I have to leave the render to dry for before it is ok to skim over it?
Do I need to wait for the render in the recess to dry/cure before I start rendering over the whole wall?
 
Build it out 15-20mm at a time key well and allow to set over night.

Once the final coat of render is on and ruled flat. Devil float it up and leave for a week to cure.

Don't confuse set and cure. To very different things.

Most damp proofers will skim next or even same day. It runs a bigger chance of skim cracking or blowing off in sheets. Not always but can happen.


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Really? How do you justify the cost of replastering 3m2 20 miles away? Or do you not take them on?


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That helps. I have work for 3 dpc firms over the last 11 years. Everyone I have ever encountered skimmed same or at least the very next day. I thought everyone did till I came on here 6 years ago lol


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Thanks very much guys. That's really helpful, one more:
How long do you have to leave between render coats? The damp proofed said I need 2 layers, but where the chimney breasts were that will be 3-4 layers at least
 
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looky said:
Thanks very much guys. That's really helpful, one more:
How long do you have to leave between render coats? The damp proofed said I need 2 layers, but where the chimney breasts were that will be 3-4 layers at least
Click to expand...
orry, I forgot to add; there will be waterproofed added to the 3:1 s:c mix, does this effect curing time between coats?
 
You need it to set, so the last coat doesn't pull off with the weight of the next coat. That will depend on suction etc. The waterproofer will kill the suction. So once the scratch coat is on, the next coat will hang for ever if you put it on the next day.


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So a coat a day and I should be good? I don't know what hanging or lashing is.
Thanks again for the help
 
Have always put a drop of water proof in the top coat, Devil float it and skim the next day, the water proof stops it from sucking in to quick on lager walls, especially if you have left them for a while.
 
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Two days is plenty ,I have skimmed the next day but normally I leave it two days ,over here it's mostly sand and cement then skim over I'm at it 26 years never had a problem
 
looky said:
Hi, I'v got a couple of walls that I have been advised to sand and cement render to protect against damp.
It is a bit of an ordeal because where I removed two chimney breasts there are 2m wide and 7cm deep recesses, so I need to build out the recess until flush with the rest of the wall and then render the walls.
I want to know how long I have to leave the render to dry for before it is ok to skim over it?
Do I need to wait for the render in the recess to dry/cure before I start rendering over the whole wall?
Click to expand...

The correct answer to your question is 6 weeks. But f**k that 3 days to a week no problem
 
carlos said:
That helps. I have work for 3 dpc firms over the last 11 years. Everyone I have ever encountered skimmed same or at least the very next day. I thought everyone did till I came on here 6 years ago lol


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Click to expand...
Yep I've laid on three coats and skimmed all in one day ,lovely cos it slows skim setting time never had any separation or cracking either i think due to the slower and more even drying time.
 
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