Rendering over new blockwork

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User___removed

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anyone got any idea what the recommended time is to leave new blockwork before render
I thought I read somewhere 4 weeks?
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Mortar is pretty much set after a week but reaches full strength after a month.
 
I've rendered plenty of block houses with sand and cement.
Normally they would have sat for 2-3 weeks while the roof and slates get fitted. I can't see you having any problems.
It's not as if they will build the whole house in one day then tell you to render the next.
 
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I meant you are increasing your chance of cracks somewhat if you are gonna go on it that quick, especially single skin block tied into a timber frame.


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I find with most timber framed houses that they do crack more than a cavity build. Some people let the scratch coat sit for a week before finishing but I've seen it finished the next day to avoid high suction on large areas.
I have never had a problem with rendering using 3+1 scratch coat and 6 sand 1 cement + half a lime top coat.
 
You might be OK after a day Bobby who knows for sure?
Ultimately though, you've two separate lots of shrinkage & settlement in the timber & block.
However if I was under pressure I'd probably be on it after a week, full mesh??


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If you wanted to be really thorough then use a moisture meter and wait until the mortar is within 20% of the block moisture content.
 
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