New Barratt homes covered in 'black mould'?

[GreenDragone]

Daily Fail article here

Anyone here who really knows their stuff regarding house render? I was shocked at these pictures in the news tonight. These houses are only 6yrs old!! I query it because I live in a rendered house which needs painting from time to time (about every 10yrs) but it's never looked like this & I live in a filthy major city. What do you think the real cause is? It doesn't look like 'iron stain' from pebble dash. Could it really be only from condensation? Barratt are having nothing to do with it apparently. No surprise there.

No idea but following as I always wonder when I see it..

There are houses like this local to us. They are right next to a bond warehouse which stores whisky and apparently that's what causes it

I would say that your pictures show something environmental rather than anything Barratt has done (or not done)

it looks to me like the paint is eroding away and the render is showing through. Probably caused by incorrect preparation or skimping on coats.

Is that the side that gets rain blown on it?

on the gable walls, that is. The black stub walls are very strange. Has anybody been standing flowerpots or plant troughs on them? I see not all the walls are marked.

I had an idea about the stub walls - the porch roof above dripping onto them. The porch roofs appear to have no guttering. The stub walls themselves have convex tops so you couldn't stand a plant-pot on them. I wondered if the gable walls were north facing as that can make things worse.

I have seen countlesss houses like this in Cornwall. The salty sea mist attacks the paint. There are specialist paints that greatly help with this but it is unlikely a major builder will use them due to cost.

We had a similar problem with our paint when a small builder built just 12 houses where we are in Cornwall. It is cutting costs and, of course, the owners do not know what they have done so a few years later the mould appears. Ours was actually more red/grey mould but looks similar. The only thing to do is go back to basics. Clean it off. Use a strong anti fungal cleaner and base coat and buy the best anti fungal paint you can get. Then do two coats.

As ours is a town house, we decided to clad the top two floors so we now only have to worry about the ground floor external paint which we can easily reach. Several other houses had cladding right from the start, and they were perfect after 10 years. The painted ones all have problems. So far, we still a have a good finish. On paint and cladding.

I've also seen this next to a bonded whisky warehouse.

I'm also guessing it could happen next to a busy road with dirt from exhaust pipes.

Just wanted to help with any concerns over this staining. please visit our website for additional info if required (algoclear.com).
The staining is an algae called trentpohilia sometimes called red algae, the red is a beta carotene thrown out by the bacteria to protect itself from UV.
The problem is environmental - not a failure of the render or coatings. It's becoming more common as home insulation is improving - we all know what happens to a surface when one side is warm and the other cool, the perfect breeding ground for bacterial growth. It's easily solved using a non-invasive DDAC (Do not use bleach). There will be a local contractor who can solve this for you - always ask for copies of safety data sheets of products they are using to ensure it's safe, bio-degradable, sustainable and guaranteed not to adversely affect any materials, products, coatings or sealants used in construction - if they can't do that find someone else.

The bacteria you mention is often called "angels share", common around brewery;s and distilleries.

external your post makes perfect sense. The render on those houses isn't damaged, the mould is superficial.