New external plaster cracking

[endamc]

Hi
I'm a builder and we've plastered sand & cement outside instead of k-rend or the like as we thought its the safest option to avoid any problems(or so i thought).
After a couple of months we noticed after rain the plaster would have a turtle shell effect as i would call it and now after 9 months even when dry theres same effect if you look long enough at it.
The plasterer used SBR as he said it would best mix to use.
Just looking somebodies opinion on it.
Thanks
Endamc

 

[Rigsby]

Sounds like crazing. When it is dry it looks fine then after rain and on drying out you notice crazes all over. I have had it but once painted the problem doesn,t show.

It can be down to several things. The 2 coats applied too soon and not letting the scratch coat dry out first. The render is too rich in cement or has dried too soon. A trowel finish on setting then lightly sponged. Soft sand used instead of washed plastering sand.

If you painted it the first coat will show the crazed until dried then it should be ok. If the cracks are visible when dry then consider a thin coat render over the top fully meshed with a synthetic finish. You can get equalising paint and synthetic finish that can go straight on top and is crack bridging.

 

[DannyMac]

A picture would help here.