Efflorescence Problem

[John Smith Esq.]

Hi everyone,

Our new extension was finished in September and there are a lot of salt crystals coming through the mortar joints below the DPC. To the point of being all fluffy. I keep brushing it off from time to time with a hard brush, but it soon comes back and even when removed, leaves a somewhat unsightly white colour. It doesn't seem to be on the bricks themselves and not above the DPC yet. I assume it is because off all the moisture from the ground. Questions from me:

a) will this process ever end?
b) is there anything else I can do?

Thanks

 

[Odds]

You can buy treatment to spray on an affected area but check inside to see if any damp issues are present.

 

[stuart45]

It's probably lime run off. It looks similar to efflorescence, but being lime when it carbonates it can be harder to remove.
It's quite common with engineering brick walls, as the bricks send most of the water into the joints rather than absorbing some. Free limes are a by product of the OPC hydration, and engineering bricks are usually laid with a stronger mix, so there is more of it.
You are better to remove it before it carbonates, or it could need acid to clean then.

 

[^woody^]

Fluffy=efflorescence.

 

[John Smith Esq.]

Fluffy=efflorescence.

Is there anything I can do other than keep brushing it off?

 

[^woody^]

Is there anything I can do other than keep brushing it off?

Not really, as once salts are activated, future moisture evaporation brings them to the surface. The process is generally seasonal and random, and can take a very specific set of circumstances to occur - therfore may not occur all the time or every year.

Standard advice is dry brushing only, no chemicals and no water. Eventually, the causation salts are extinguished, but how long that takes will be unknown.

 

[John Smith Esq.]

Not really, as once salts are activated, future moisture evaporation brings them to the surface. The process is generally seasonal and random, and can take a very specific set of circumstances to occur - therfore may not occur all the time or every year.

Standard advice is dry brushing only, no chemicals and no water. Eventually, the causation salts are extinguished, but how long that takes will be unknown.

Thanks.

Is this common and normal, or indicative of something not done right? Just wondering as I am planning to replace the outer skin of bricks on another part of the house so could try to do things differently for that.

 

[^woody^]

It's a phenomenon, so occurrence can be random. The salts may be in certain clays or sand, but may remain effectively dormant.

Saturation of stored materials, and the tops of part built walls is a significant cause, so there is good practice for that.

Also, voids in the wall from either furrowed or part filled joints, and unfilled frogs which hold water and when that begins to move out, can activate salts.