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Rob70

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hi, not being in the trade myself, I thought I'd ask you knowledgeable guys on here.
I had a scratch coat applied to my single storey kitchen extension which seemed fine. The guy who done it never came back to app,y the top coat 6 months later I got someone else to do the top coat. They asked me what strength scratch coat had been used but I didn't know.
He done the top coat but after about 4 weeks it started blowing and cracking badly, with large sheets of scratch coat and top coat literally falling off in one down to the breeze blocks.
He came back to look and said it was down to the scratch coat not adhering, whereas someone else said the top coat he put on was way to strong and has pulled off everything.
I would really appreciate your thoughts.
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Normally the scratch coat is a stronger mix than the top coat. As you've had 2 different people do both coats this can cause a problem as the second guy wont know how strong the scratch is. Also the scratch may not have a waterproofer in it which allows the topcoat to cure rather than dry. If thats the case it will suck the moisture out of the top and may not adhere properly finally your scratch coat doesnt seem to have enough of a key to it. Hard one whos to blame although if i was the second guy id be reluctant to take the blame but this would have been explained before I started
 
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Well the scratchcoat looks well and truely on there. Breeze blocks are high suction so im.guessing when he topped the render it went off very quickly. This will result in whats happened there as there is no suction control
 
Should have SBRed the scratch coat 4-1, couple of coats.

That top coat looks strong, 3-1 I reckon, too strong.
 
beddy said:
Normally the scratch coat is a weaker mix than the top coat. As you've had 2 different people do both coats this can cause a problem as the second guy wont know how strong the scratch is. Also the scratch may not have a waterproofer in it which allows the topcoat to cure rather than dry. If thats the case it will suck the moisture out of the top and may not adhere properly finally your scratch coat doesnt seem to have enough of a key to it. Hard one whos to blame although if i was the second guy id be reluctant to take the blame but this would have been explained before I started
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The scratch coat is always stronger than the top coat not weaker,?
Also if the scratch coat has been on that long it should have a coat of pva/Sbr before top coat goes on
 
Thanks for your input guys. Not looking to blame anyone, just curious as to what has happened. I know people done like finishing other people's jobs.
 
Rob70 said:
Thanks for your input guys. Not looking to blame anyone, just curious as to what has happened. I know people done like finishing other people's jobs.
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looks like its a hack off and re do... if you let us know hwere you are maybe someone from here could help :D
 
Ah right somebody else finished it?? Looks crap and better it fell off if you ask me get a professional next time?
 
The scratch looks like it's full of pit/play sand, very weak and very thin with no key.
Take the lot off and pay another person to do it again.
The 2nd bloke can't be that good by going over what's there anyway.
I'd say no straight away knowing there is a risk it could come off after I'd gone over it.
 
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