hairline cracks in render

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neradv

neradv

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can anyone give advice on a problem concerning external render, I have hired plasterers in to render a timber frame extension I have built for a customer, the external covering consists of 12.5mm ply, building paper, EML, scratch coat render of plastering sand, bit of sharpe sand and OP Cement with waterproofer and plastisizer, after two weeks of rendering being finished, have started to notice hairline cracks are appearing, some 3mm wide others smaller and they all seem to join in a craze type effect, any ideas, cheers
 
.what strength were the mixes, how long between coats, was an air gap left behind the scratch, any fibres used ,any mesh used,was it kept wet or at least protected from sun ?
 
the mix was 4:1 top coat was done after a few days when dry, used metal lathe straight onto building paper on ply, shaded from sun, left to dry naturally
 
You should have had battened the ply,then eml over the battens with the breathable behind it,leaving an air gap,should of left a week between coats,and kept first dampened,although most of us don't,second coat should of been weaker with lime also in my opinion, @essexandy @ superspread @Arti
 
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johniosaif and ryanswart has hit the nail on the head , and should be 3 coat on eml anyway, and you dont need waterproofer and a feb
 
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over mixed and over plastisized render has the same integral strength as angel delight . You should of had the eml on the battens with the building paper under the eml , you should done 3 coat render spread over at least 3 weeks render fibres also in the first 2 coats wouldnt of hurt , 4-1 ,5-1 and 6-1-1 would of been about right mixes wise and i would of gauged the mixes in a bucket so theres no room for error .
 
during the war , it was allways 3 coats , a pricking out coat followed by a ruled stratch coat then a ruled top coat and now theres a new product on the market called rib lath :RpS_thumbup: thats even better than eml
 
Im suprised they didnt go for a render carrier board and a thincoat render with a timber frame
 
jesssop said:
if you said that to a builder round here they wouldent have a clue what your talking about
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I dont either, i just have breakfast with Rich Lord now and again and he enlightens me.....................:RpS_thumbup:
 
Plaster sizer and waterproofer in the same mix !!!!!!!!! they would work against each other as one puts air/bubbles into the mix and the other tries to get rid-of the air bubbles .....lol builderssssssss
 
gooner59 said:
Plaster sizer and waterproofer in the same mix !!!!!!!!! they would work against each other as one puts air/bubbles into the mix and the other tries to get rid-of the air bubbles .....lol builderssssssss
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Lol ,ninety percent on here do the same.
 
gooner59 said:
Plaster sizer and waterproofer in the same mix !!!!!!!!! they would work against each other as one puts air/bubbles into the mix and the other tries to get rid-of the air bubbles .....lol builderssssssss
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2 posts to go :RpS_thumbup:
 
gooner59 said:
Plaster sizer and waterproofer in the same mix !!!!!!!!! they would work against each other as one puts air/bubbles into the mix and the other tries to get rid-of the air bubbles .....lol builderssssssss
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Freeflo does both :RpS_thumbup:
 
Hi rib, no one wants to pay for it tho.

did a 2 coat over EML with fibres last year ( customers budget) over painted flaky brickwork.

disagree about them strengths , scratch 7/2 with fibres, rub up 5/1/1, waterproofer in both coats. A couple of fine hairlines and that's it.

fixed EML on with millions of fixings, then " pulled " the mesh out to give some space for scratch to get behind. Job done, cash in pocket
 
irish_spread said:
Hi rib, no one wants to pay for it tho.

did a 2 coat over EML with fibres last year ( customers budget) over painted flaky brickwork.

disagree about them strengths , scratch 7/2 with fibres, rub up 5/1/1, waterproofer in both coats. A couple of fine hairlines and that's it.

fixed EML on with millions of fixings, then " pulled " the mesh out to give some space for scratch to get behind. Job done, cash in pocket
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So you 1st coat 3 and a half to one cement ? sharp sand ?
 
Yep.
Soft washed, selco sand. Painted brickwork, no suction, just mechanical. 2nd coat made flexi with lime. W/proofer in 1st coat reduces rapid set of second coat. Little bit of sharp would help though.

in Ireland the sand is a lot coarser but lovely to use. Mainly concrete blocks there but very very rarely see any cracking
 
church said:
thx mate handy to know :RpS_thumbup:
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Not saying I'm 100% correct mate. everyone has their own methods but works for me. Did the job last summer and drove past last week and saw 2 hairlines bout 1/2 metre long where she had put drilled new down pipe and a PIR.
would have preferred 2 scratch coats but she's thinking of selling soon and didn't want to pay the extra. Told her it would sound blown but she could show pics of the drilled and plugged EML to the surveyor
 
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