Layers Falling Off Brickwork

[Bert]

Our house was built about 30 years ago with London Windsor bricks. Even with cavity wall insulation it seems that enough heat leaks out to keep most of the bricks from freezing in winter.

However, the chimney area is showing signs of frost damage, with thin layers falling off. (We have not lit a fire this winter). There are a few bricks on the wall of the unheated garage that have lost slivers of brick, and the garden wall has similar damage.

Could you please advise what is the best thing to do to prevent further damage - would Thomson's Water Seal be any use? I believe that this has to be reapplied every few years. Is there a once-and-for-all treatment?

Is there any method of repairing the damaged bricks? - I would doubt it, but you never know. When we had double glazing installed the fitters made "repairs" to the corners where the thick wooden sills were removed, by some sort of red brick coloured paste, which set. Unfortunately the colour match was not good.

Why is it that houses built 100 years ago do not have this sort of damage?

[The Builder]

There's been a lot of this for the past few years. On render as well. It's a combination of lots of rain (soaking the brickwork), followed by periods of diabolical temperatures. The face of the brick "blows".

Masonry follows a continuous cycle of rain/ evaporation by air-drying/ more rain etc etc. I can only imagine that at times, evaporation can't keep up with the rain.
Rarely seen in some very old bricks unless they're laid as garden paths, where they stay wet and sheltered from drying air. They often blow in this situation.

I don't know, so I'll take an educated guess that old bricks were handmade, and turned out of a wooden mould ready for firing. Faces were natural. Often cut with a wire (as per a cheesewire) (Hence "Wirecuts") They had no decorative face applied to them, so nothing to de-laminate.

Modern bricks often have a common "core", but different "slips" are applied to give countless varieties in colour/finish etc. I would guess that's the bit that blows off.
Just a guess. I'll have to do some research :o)

Cutting the affected brick out and replacing is the only way.

Silicone-based products like Thompson's are ideal for chimney stacks. I've used it myself. Not as good as a rebuild of course, but certainly better than porous masonry.

It's not as onerous as you might think to cut out brickwork. If you don't have an angle grinder to cut the mortar joints, then make lots of holes with a masonry drill... until they all join up.

[bushbaby_de]

We've got exactly the same problem in my 10-year-old house, not with the house bricks but with the garden retaining walls and steps. I've got a builder coming round to cut out the front brick course and replace them with 'full engineering bricks' apparently! He said there was a way of treating them to prevent more damage, or that individual bricks could be cut out and replaced, but we've decided to go with the re building option since its such small segments of wall anyway.