Why do bricks on walls go white /scale colour?

[ey143]

Could someone please explain to me why some very nice looking external brick walls, go white as if they were growing limescale, during certain times in the year?

How can this be prevented or if I was to have my own wall built, what precaution should I take to ensure that I use quality materials to prevent this from happening?

 

[PrenticeBoyofDerry]

http://www.ibstock.com/pdfs/technical-support/TIS-02-Efflorescence.pdf

 

[ey143]

Thanks for the link, but Im not sure it was if the PDF was that helpful. Kind of stating the obvious or mentioning general stuff. My neighbours wall (which suffers from this) is rock solid and looks good quality. I'm not sure if just "avoid dipping the bricks of not facing the wind" is the solution.

Can this be avoid by buying anything other than portland cement?

 

[tony1851]

You don't say if the neighbour's wall is newly built, or old.

If new brickwork, it would be normal for salts to form on the surface in the year or two after construction.

If it is an old wall, efflorescence can be an indication of dampness.

Usually, it's not harmful - just an aesthetic problem really.

 

[ey143]

Hi

The wall is about 7 years old and the white appears every year.

Thx.

 

[Joe Malone]

Was the wall built with a DPC? If not then it could be a continual problem with rising damp but this is unlikely unless the mortar mix was made particularly weak. New OPC mortar is generally impermeable to moisture for many many years. Also if this was the problem then you would tend to see the salts deposited as a tide mark at the damp apex rather than being a more generalised salt deposition. It is likely that you have salt in the building materials and there are lots of possible reasons for this. One common cause is bricklayers who add washing up liquid to their mortar mix to make it more workable. Washing up liquid contains salt as a bulking agent and will cause more problems with salt efflorescence.
There is little you can do besides brush the efflorescence off with a stiff brush as soon as it appears. This is important because the salt blocks the pores of the brickwork which ultimately leads to spalling due to hydraulic frost action.

 

[ey143]

Interesting thanks. Does the brick or cement type make any difference?

What is an ideal ratio mix for a strong wall - 3 to 1? We're taking down part of an existing wall at the moment to make way for a drive and the guy has said he has never come across a thick solid wall like ours before and has taken him a whole day to grind and kango through part of the wall we are keeping.