white chalky substance on walls

soffie

hi guys. we had this problem last winter, around Feb time this year, we had the house repointed and problem seemed to go. however it now appears to be back. i am wondering if this is just a 'winter'/mould issue instead of damp? the substance is chalky white and the outside walls have no visable issues (as above all repointed last year) so no gaps in mortar etc and when done the membrane was in tact.
the substance i could not wipe off with a finger but when i took a wet wipe to it it dissappeared easily enough.
just need advice on how to clean the area so if it is white mould (is it?) it doesnt come back, any treatments/solutions to stop this?
i was also considering put a water repellent on the outside bricks but again aren't sure if this is the issue anyway?
thank you very much in advanced.


*to add the substance is at the bottom of the wall just above skirting board. im just worried whats wrong since we had all outside repointed etc..

societys_child

Sounds like efflorescence.

Salts drawn to the surface as the wall dries out. When it gets wet it's drawn back into the masonry etc.


Plenty info and pics on the web.