Cracks on scratch coat?

Members online

Davis99

New Member
Hi. Wondered if I could get some advice.

I decided to have the front of my house sand and cement rendered as the brickwork was a bit tired.

The guy put on mesh and then the scratch coat. As the day progressed it got very very hot. He tried to keep it wet, but since he finished that coat, quite a few vertical stretch cracks have appeared.

He is doing the top coat next week as it has rained none stop recently. Although there are cracks it feels solid and he said the top coat will be fine.

I am a bit worried as the cold weather will be coming in soon,

Is it going to be a problem as he said not to paint it for 6 weeks.


Thank you for any advise.
 

Zanzibar26

Member
Its not ideal, and doubt he will give it another scratch. If its sound shouldn’t be an issue. What finish are you having? Id have concern if it was a float finish, not so much if it was pebble dash
 

Rigsby

TPF Special Forces
If it appears to be solid then crack on. The cold will be ok, safer than too hot and the damp air will help curing.

even painting will be ok, just needs a few hours to dry so pick a couple of dry days..
 

Rigsby

TPF Special Forces
Jewson Plastering sand I think. No idea what other stuff was put in. It seems solid. Just unnerving seeing all the cracks.

under the metal meshing was it brick or block with suction or did he treat it with anything? Are the cracks small and more horizontal than vertical?
 

Davis99

New Member
under the metal meshing was it brick or block with suction or did he treat it with anything? Are the cracks small and more horizontal than vertical?
It was old brick. I'm not sure if he put anything on. There were a lot of screws and washers holding it down. The cracks are ALL vertical. No horizontal ones.
 

devneydutch

Active Member
Put some pictures up so we can see what your talking about. I would paint on red grip/sbr slurry before the mesh.
 

Davis99

New Member
diamond pattern or rib mesh? both are a poor spec.as is sand and cement . there are a lot better systems available.

Diamond pattern. The guy has done good work in the past. I guess if when the 2nd finish coat is done and it starts cracking up, its the old fashionable grey facia boards to cover it all up. <sigh>.
 

malc

TPF Special Forces
Diamond pattern. The guy has done good work in the past. I guess if when the 2nd finish coat is done and it starts cracking up, its the old fashionable grey facia boards to cover it all up. <sigh>.

that will crack alright! as the temp. alters the metal will expand and crack the render.
 

Davis99

New Member
Put some pictures up so we can see what your talking about. I would paint on red grip/sbr slurry before the mesh.
I tried to take a pic of the worst bits.

render1.jpg
render2.jpg
 

bof

Well-Known Member
that will crack alright! as the temp. alters the metal will expand and crack the render.
Never had an issue malc , steel has the same expansion rate as concrete
My only issue is customers won't pay for stainless, just have to take care with trowel and float
 

malc

TPF Special Forces
Never had an issue malc , steel has the same expansion rate as concrete
My only issue is customers won't pay for stainless, just have to take care with trowel and float

the EML is fitted to close to the brickwork therefore mortar can not get round the back of the lath for its key.
we have not used metal lath for 30 years, there is no need to use metal with the fibre mesh that can be buried into the polymer base coat a far improved system.
 

bof

Well-Known Member
the EML is fitted to close to the brickwork therefore mortar can not get round the back of the lath for its key.
we have not used metal lath for 30 years, there is no need to use metal with the fibre mesh that can be buried into the polymer base coat a far improved system.
Didn't notice mesh too tight , but as I said , done right should have no problems with expansion ,
stopped rendering over 25 years ago but would probably still use eml as you have fixings for extra security

Old (ish ) dog etc lol
 

Kinkyboy

Well-Known Member
the EML is fitted to close to the brickwork therefore mortar can not get round the back of the lath for its key.
we have not used metal lath for 30 years, there is no need to use metal with the fibre mesh that can be buried into the polymer base coat a far improved system.
Agree malc,why use eml when you can bed fibre mesh into the scratch coat! Far superior and easier and cheaper and quicker!
 

Mouldyoldspudgun

Well-Known Member
Sand and cement shrinks anyway, your first coat is to make it all one suction for the top coat, which in theory shouldn’t crack but a lot of people ( I can’t call them spreads) use s**t sand or are sold crap sand without them realising
 

Rigsby

TPF Special Forces
Thats shrinkage cracks. Either too much suction or the heat. Tap it and if it isn’t hollowthen let it fully cure for at least 14 days preferably a month then carry on.

I have seen worse.

Strange why he would use mesh on brick. If it was smooth faced or painted then yes but a bit out of date and ott.
 

Davis99

New Member
Thats shrinkage cracks. Either too much suction or the heat. Tap it and if it isn’t hollowthen let it fully cure for at least 14 days preferably a month then carry on.

I have seen worse.

Strange why he would use mesh on brick. If it was smooth faced or painted then yes but a bit out of date and ott.

Yes, when he put it up the weather turned from ok to blazzing hot, so he couldn't stop half way through. Its been 3 weeks now and he's coming back to do the top coat next week. The cottage is old with 1930's brick and lime mortar joints. I guess the mesh was used because of its age. The cracks were defiantly caused by the hot day. I have done the tap test. If feels solid, no hollowness. Just worry when the top coat is on the cracks in the scratch coat will come through. I have a plan B with the grey cladding, but still a waste of money if it fails.
 

Kinkyboy

Well-Known Member
Yes, when he put it up the weather turned from ok to blazzing hot, so he couldn't stop half way through. Its been 3 weeks now and he's coming back to do the top coat next week. The cottage is old with 1930's brick and lime mortar joints. I guess the mesh was used because of its age. The cracks were defiantly caused by the hot day. I have done the tap test. If feels solid, no hollowness. Just worry when the top coat is on the cracks in the scratch coat will come through. I have a plan B with the grey cladding, but still a waste of money if it fails.
If its sound and not hollow then it will be fine,if it was hot your bound to get some shrinkage cracks.it will be fine
 

Rigsby

TPF Special Forces
Yes, when he put it up the weather turned from ok to blazzing hot, so he couldn't stop half way through. Its been 3 weeks now and he's coming back to do the top coat next week. The cottage is old with 1930's brick and lime mortar joints. I guess the mesh was used because of its age. The cracks were defiantly caused by the hot day. I have done the tap test. If feels solid, no hollowness. Just worry when the top coat is on the cracks in the scratch coat will come through. I have a plan B with the grey cladding, but still a waste of money if it fails.

You have left it to cure so it will be fine.

Are you going to paint it? Jub make a siliconed paint that has some stretch in it or better still apply an acrylic or silicone render finish 1.5mm. Plenty of stretch there.
 

Davis99

New Member
You have left it to cure so it will be fine.

Are you going to paint it? Jub make a siliconed paint that has some stretch in it or better still apply an acrylic or silicone render finish 1.5mm. Plenty of stretch there.
Thanks.

I was told not to paint for 6 weeks.

Should I add some of that clear weather proofer in the meantime when its had the face coat?
 

Rigsby

TPF Special Forces
Thanks.

I was told not to paint for 6 weeks.

Should I add some of that clear weather proofer in the meantime when its had the face coat?

Yes leave it 6 weeks but do not use that clear stuff it’s water repellent but it doesn’t know the difference between wet water and wet paint, it will repel both.
 
Top