Render staining, build design fault or something else?

[Bri44]

Hi all.

After some advice.

My render has terrible staining after it rains. It is Green, Black, Red, and rusty colour.
Is this due to faulty render?
Render not applied correctly?
Lead not treated on the ledge?
No draining on the ledge?

I have looked at other houses all within 100 metres of mine. They are older than mine and all face the same way. They have only minor dirt stains. I took some pictures to compare just after it finished raining.


My house.




Nearby houses.

 

[KenGMac]

Bri44, good evening.

In images 3, 4, 5, posted, the ones that are close ups, appear to indicate what was a common problem in Scotland which is that the sand used in the render mix contained a form of Coal? it is called Lignite or "soft coal" or " brown coal"

If you have a close look, at the images, you will see a small dot of [fairly] intense black spot, from this [spot] there is a downward triangle of a dark colour.

What is happening is that there is a tiny inclusion of lignite, this material is being "attacked" by the rain water, the lignite being very soft will "bleed out" and cause the triangular staining on the surface of the render. The staining is persistent and will not wash off with more rain.

Ken

 

[Bri44]

Thanks for the reply Ken. Is there any fix for this?
The developer has said they are going to repair cracks, clean render and then paint it.
Not sure if this will prevent the cracking and staining in the near future.