cracks in exterior render

[Frankiebaby]

I have recently noticed some exterior render cracks that may be causing damp on an interior wall. The cavity has been filled with injected insulation and I cannot be really sure if the insulation is acting as a bridge within the cavity to carry water to the interior wall. I have bought some filler that claims to resist cracking and shrinkage but it needs to be applied to a dry surface. As we are now well into quite a wet October it is very unlikely that the surface will be dry enough to apply the filler. I have filled one of the cracks before with a sand and cement mix but it always cracks again thus the reason for wanting to use a filler that is flexible. Any suggestions?

 

[ree]

How old is the house?

Render is typically applied because of some underlying difficulty.

A Pre-cav insulation survey should check:
why has the wall been rendered?
Any cracks present?
Any bulging present?
A Boroscope view into the cavity looking for bridging debris and snots on the cavity ties - are ties present - in what condition?
Any existing damp on internal walls?

How soon after rain does the internal damp show? Does it have a wall pattern?

Pics of outside and inside will help us to help you.

There are many similar posts on here and in the plastering forum if you search.

 

[JohnD]

no reply yet?

 

[Guitar_man]

You would be surprised how much water can be trapped behind and enter through cracks in render. The building acts as a sponge and sucks it in. You need to cut a 6 inch channel along the crack and rerender it. If the crack is bad apply a wire mesh before you apply the mix. Obviously knocking off and redoing the whole wall is the preference option. Filler or silicon never works.