Blown plaster caused by disintegrating brickwork

Phil Addison · 2017-05-17T16:31:10+00:00

Back to DIY after a long break and I'm easing in with what should be (have been!!) a simple job, redecorating the spare bedroom. However, after steaming off the old wallpaper I discovered some very large swellings of the plaster. By large I mean about 9" to 12" diameter and protruded about an inch at the centre from the surrounding flat wall surface. On investigation with hammer and chisel I found several soft bricks where the surface in contact with the plaster had disintegrated to powder, and this had expanded behind the plaster blowing it off. I've hacked out the softest stuff and after 1/4" to 1/2" deep reached reasonably sound brick, although still soft, i.e. I can scratch a line into it with the edge of a cold chisel. The wall is the end wall of a Victorian extension, single skinned about 12" thick. So far, on a section of wall 8'6" high by 3' wide, I've uncovered 4 of these crumbly bricks. I suppose they are from a stock of sub-standard bricks that the Victorian builder used up, a few into each wall. The bricks of course are imperial 9.5" x 3.25". The question now is what to do about it. I'm wondering about a) cut out the complete bricks and replace with good ones, b) Chisel off as much soft stuff as I can, and refill with cement mortar, c) Drill a few holes into them and inject silicone waterproofing. Followed by a new scratch coat and plaster skim, having hacked off all loose old plaster, which probably means all of it! Suggestions as to the root cause and how best to fix it gratefully received! There are photos on my OneDrive site: Phil

May 17, 2017 23 Replies

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Phil Addison 9 years ago

Yes, I thought it an excellent guide too.

I had noticed the existence of mortar guns before but assumed they were a gimmick. From what you say I'm very tempted to get one as I also have a garden wall in need of pointing as well as these blown bricks.

Has anyone got any specific brand recommendations? Google/eBay brings up

Everbuild at about £30, Roughneck and Faithfull at about £20-£25, Hilka £15, Silverline £10 (isn't that Aldi brand?).

Roughneck seems to have most sellers.

Phil

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newshound 9 years ago

One of those things you might not use often, but when you have a use for it, it is quicker and more effective than "trowelling", particularly for filling deep holes completely.

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tabbypurr 9 years ago

gimmick. From

need of pointing

I wouldn't use one for this. Why? they're rather fussy about the mortar mix , which will waste plenty of time. Then you've got to clean it out afterwar ds.

Silverline is not Aldi.

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newshound 9 years ago

I've had a couple, I doubt if there is very much to chose between them. One came from SF/TS and it certainly looks like the Roughneck pictures (< £20 from SF/TS/Wickes). You might be getting extra tools or nozzles with the more expensive one.

Silverline is generic, Silver Crest is a Lidl name.

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