Curing spalling bricks with render?

[deano]

Have been asked to look at rendering a whitewashed brick wall that is spalling. It's a freestanding external wall, no buildings either side.

The bricks have been de-facing for some time and are getting worse so the owner wants a cosmetic revamp in the form of a flat coat render... finish coat over a scratch coat.

It's a problem I see a lot and wondered the best method of going over this with render and ensuring that the blowing does not continue in the future to ruin the new work.

The wall is topped with soldiers (in black, atop standard reds) and I was thinking about putting a run of coping stones along the top with overhanging drips to keep water away from the render.

What else can I do to guarantee that the render doesn't start blowing away in the future... as has happened in my own garden (grrrr)?

Aside from the copings, any additives / pre treatment recommends?

Tnx deano.

[The Natural Philosopher]

USE a STRoNG render and add proprietary water proof coating before painting.

Wont be any good if the damp is rising tho.

[Dean Heighington]

PVAing the render before painting? I did this in my own garden and the render blew over time and I assumed it was because the PVA and the paint wasn't letting the moisture out by allowing the render to 'breathe' Admitted, I didn't have copes along the top but given that the wall is freestanding and water can permeate through from the other side, is it wise to prevent it escaping through the new side with a waterproofing coat prior to paint?

What I need is a Gortex paint :)

Or did I misinterpret your post?

Of course! Hadn't considered that- will need to get my damp meter on it and check for a dpc which I doubt they incorporated!

[Andrew Gabriel]

It's impossible. Either the wall was built with wrong class of bricks (too absorbant for an outside wall), or it's simply reaching the end of its life.

You may be able to slow it down, but you can't stop it.

I would remove any loose brick faces. You could cut out and replace any really bad bricks, but that might be a never ending task.

Capping, with a good 1" overhang each side including a drip channel.

Anything you do to try and waterproof it tends to be more effective at keeping water inside the brickwork than it is at preventing it entering.

[Tabby]

Pva falls apart when it gets wet for long.