Brickwork


On the front of the garage conversion, where the garage door was bricked up, the lower courses of brickwork are beginning to show a white deposit - rather salt-like - on them. It seems to occur in the lower half of the wall (unless it's rising - though a DPC was put in), which is a red brick, as opposed to a normal (yellow?) brick on the upper half.
The mortar seems very firm, so I am a little stumped as to what this is. Is it normal? Building work was done about 9 months ago.
Cheers
JW
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John Whitworth wrote:

That's normal John and it's simply the 'salts' coming out of the brick.
I've seen this dozens of times on newly built walls of clay bricks, and it can be quite unsightly - and a right PITA to get rid of - if that is at all possible!
Cash
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Cash wrote:

It's posh name is efflorescence, as said already it is dissolved salts coming to the surface and then the water evaporates leaving the white stuff. If you wash it off all you do is dissolve it and it soaks back into the brick only to come back. Best is to rub it off with a stiff dry brush from time to time. I have a patch of this on my house and the house is 18 years old, so don't expect it to go within a month or two.
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I saw a newly built block of apartments in Shrewsbury recently and all the brickwork had this stuff all over it. A lot of new brickwork seems to be affected by it, did the exceptionally cold winter have anything to do with it?
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Thanks guys. A relief that it's normal then. Definitely is just the red brick that's doing it. It's actually hidden behind our beautiful collection of three wheelie bins, so not a major issue. I wouldn't have been able to hide a fallen-down wall though! :-)
Cheers
JW
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If that's the only place, it could be caused by rain splashing onto the wall from the top of the wheelie bins, and then drying out, carrying salts with it.
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Andrew Gabriel
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writes:

Could be - I'll never find out I guess, though, as there's nowhere else to put the bins. Need to build a garage for them! :-D
I will try dry brushing it off, and see what happens.
JW
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A wire brush may leave a metalic finish on the brickwork. A bristle brush is worth a try, but I'd not be too hopeful.
I'd try an acid. You could try a bit of clear vinegar on a small area to see if it dissolves in acid - brush in, wash away, and leave to dry. If it works, then move on to brick acid, unless you have loads of vinegar to use and it worked quite quickly (again, test a small area to make sure it doesn't damage any finishes). Beware of acid handling (splashes, washing it away and neutralising the area).
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Andrew Gabriel
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Andrew Gabriel wrote:

Andrew,
Over many years, I've been involved with literally dozens of walls showing this phenomena (and my ears bent many times by irate householders) and no matter what was tried, we never found a permanent cure for it - though it will lessen of its own accord over many years.
I've even had the odd wet-behind-the-ears, new Clerks of Works (who really should have known better) nagging me about the bloody stuff on the odd occasion - and boy am I glad that I have now retired from the aggro of it!
Cash
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On new builds, it's usually caused by the bricks having got excessively wet before use and/or having been left in contact with the ground, and it should not reform once the brickwork has dried off and the efflorescence gone. On older structures, it's caused by a steady migration of moisture through the brickwork.
The other factor is the type of bricks used. Bricks are classified in many ways, and the two key ones here are the frost resistance (absorbtion), and the salt content. Traditionally, garden walls have required best specification here because they are exposed to the weather on both sides, and have no continuous source of heat for drying out. Compare this with house bricks which are only exposed to the weather on one side, and have a continuous source of heat leaking out of the house to dry them before the moisture soaks in very far, and you can see they don't need to meet such stringent requirements. (In practice, garden walls are often built with the same bricks as the house, but with a significantly shorter life expectancy.)
What may be happening as building regs tighten up on heat loss is that bricks which would once have been fine for the outside walls of a house providing there's some heat loss, are no longer adequately protected against moisture effects given there's now almost no heat loss through walls. That's something to consider before lining the inside of your Victorian house with insulation, but it also demands higher quality bricks for new builds, and I'm not convinced this is always taken into account.
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Andrew Gabriel
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