What to do with this external wall?

[robodelfy]

Hi, I noticed under my bay window outside it sounded hollow. Then I chopped off what you can see in the photo. But it doesn't seem like proper render, more like filler or something. It's white and a little bit soft/chalky.

It seems to be only under the bay window, the rest of the house is fine.

But I am planning to paint soon and need to sort this patch out. I've messaged quite a few renderers and most just said 'i don't do that kind of thing!'

One guy said it's not scratched so can't really just render over it. But he didn't suggest what I can do

So I'm a bit lost. Any ideas? The green underneath is solid but smooth, so mayb that can't be rendered

Thanks

 

[Alastairreid]

You can scratch whats left after removing the loose stuff with a grinder then prime with some cement powder and sbr.
Let dry and patch as required...looks like snowcrete and white sand.

 

[robodelfy]

You can scratch whats left after removing the loose stuff with a grinder then prime with some cement powder and sbr.
Let dry and patch as required...looks like snowcrete and white sand.

Thanks, I'd not heard of snowcrete

So the green stuff underneath appears to just be paint on closer inspection. The rest of the house is also this colour under the current layer of paint. But whats confusing is how under the bay window they used this filler/snowcrete stuff before painting. Why would they do this?

The green surface under the filler/snowcrete seems ok, like it could just be painted straight over!

I'm wondering if I can just chip it all back to the green, and paint directly over. I just want to know why they skimmed over it in the first place. Maybe they didnt know what they were doing, just seems very odd. And it failed in places

 

[Alastairreid]

Snowcrete is just white portland cement.
They have rendered over the green stuff without prepping or undercoating...was always going to fail.

 

[robodelfy]

Snowcrete is just white portland cement.
They have rendered over the green stuff without prepping or undercoating...was always going to fail.

Yeah but why would they bother when they could have just painted over it? Like the rest of the house was just painted over and is fine. there must have been a reason!

 

[stevethespreader]

I'm wondering if I can just chip it all back to the green, and paint directly over. I just want to know why they skimmed over it in the first place. Maybe they didnt know what they were doing, just seems very odd. And it failed in places

thats what i would do

 

[azzzaoo6]

You could use external polyfilla then sand it down to match level of old and then paint it £10 a tub.

 

[Harry Bloomfield]

You could use external polyfilla then sand it down to match level of old and then paint it £10 a tub.
View attachment 233133

In my opinion, that would only put the job off for a while. I would expect more of that coating to come adrift, exposing more of the green. It needs to all be removed, the green surface abraded to give a proper key then redone.

I would doubt just removing it and repainting would work - it was obviously recoated (badly) by a previous owner for a reason, the reason will be hidden damage to the render at the moment.