Roughcast Garden Wall

My new home has a boundary wall of bricks covered with roughcast. The previous owner painted it for selling so it looked quite smart last summer, but has used the wrong white paint which washed off over the winter, and what hasn’t washed off is a sort of flaky powder. The roughcast seems sound though. There are moss patches as shown in the photos too. Could anyone advise me about what to do with the wall? I’ve read lots of conflicting advice about wire brushes, power washers, herbicides and paints and would be glad of recommendations on how to treat this wall. The side of the wall which faces the house is much worse as it doesn’t get sun, but I’d prefer the outside didn’t look as much of an eyesore to passers-by.

 

Hi @Scotmac if you use a rough brush on the wall, you can get off bigger moss patches. Bleach is also good for dealing with algae - I was recommended to spray at 1/3 bottle strength on my house walls, leave for a couple of hours, then spray clean water. Not good for nearby plants though!
To repaint, Sandtex is good - applied with shaggy roller designed for rough cast

 

Hi,

No painting expert, but suggest you avoid heavy cleaning like a power washer or wire brushes as you may damage or lift off the roughcast.

We would use a safer product like Algon to clean off the moss/algae and then try a paint like genuine Sandtex which we have used on our garage for many years.

One thing not made clear, on the other side of the wall is the ground level the same as yours ? If its higher then you could have a problem with the damp coming though the wall, are there any weep holes near the bottom ?

Algon Patio Cleaner - Algon Organic Path, Patio & Decking Cleaner

 

Hi @ricky101, thanks for your reply. That’s good advice about gentle cleaning and makes sense. The garden is slightly higher inside the wall, and slopes down to the wall. It’s mostly laid to grass. There are no weep holes that I can see, but outside the wall is poorly maintained pavement. I think water would drain across the pavement from weep holes.

 

My house actully has a similar finish, I've always used Sandtex smooth finish on it and it lasts 10 yrs or so.
I think you can get stabilising solution if the surface is chalky/ powdery.

Obviously if water is coming into the wall from the other side you may have a problem getting anything to stick.

 

There is a product known as Snowcem plus which is cement based, not plastic, and which allows damp strata to breath. It was the original replacement for whitewash , and used extensively on concrete block structures before marketing with sheepdogs became popular....
Snowcem Plus - Northern Paints & Coatings

 

I used snowcem years ago, not sure what the plus bit means but back then it was kind of powdery after a while, you didn't dare lean on it.
Hopefully they have overcome that problem.

 

Apologies @CarolineL , your post didn’t show until later. The front of the wall abuts the pavement, which is holey and weed riddled. The garden on the garden side of the wall is higher than the pavement on the outside, and I’ve just inspected it and found there are no weep holes. On the outside of the wall, where the garden slopes down on the inside, the roughcast has come off and the bricks underneath are covered in moss and look damp. I think I’ll have to get someone in to look at it, as it’s a very long wall and I’d like to save as much of the roughcast as I can.

I’ve used Algon a few years ago on patio slabs, so I’ll try that first on the moss. Sandtex is a masonry paint I’ve used before, so once I’ve had the wall looked at I can use that. I hadn’t heard about stabilising solution @pete, so I could have a look at that once I’ve had a go at scrubbing with a brush. I just wonder if the wall would need to ‘breathe’ though.

Thanks for the advice - I’ve got lots to think about

 

You can get Santex in a Breathable.

Masonry Paint | Exterior Masonry Paint | Sandtex

 

Thank you, @ricky101

 

Wickes appear to have stock of the Santex Microseal breathable paint and also bottles of Santex Fungicidal Solution and , if needed, Stabilising Solution.

Sandtex Fungicidal Wash - Clear - 2.5L | Wickes.co.uk

 

Oh great, I can get them all in the one place - thank you