efflouresnce in wall beside chimney

[do_it_yourself]

Hello,

im trying to find the source of the wall salts that come and go 'weather permitting'. i have traced the 'salts' to the centre of the chimney breast, that meant to me it was the lead flashing.

I went up on the roof to inspect and it all seemed ok, i even noticed the salts coming through the rendering on the chimnet stack ABOVE the flashing.

I cant for the life of me work out where the damp is coming from, so my questions is..... is it possible that rain coming down the chimney could be at fault???? if so how can i fix this, as we frequently use the fire.

or:

can rain directly penetrate through the render of the wall?

please help.

 

[justlead1]

Hi
Difficult to be specific with out history of building. It is standard practice to fit chimney DPC's (Tray) during construction in the area where i work. I have had problems with staining. On investigation over a number of years, the common denominator seem to be the sand used in the construction has been exposed to sea salt, as a result it reacts with lead/masonry causing this problem. Rain / misty conditions soak into the chimney allowing the reaction to take place. If the chimney is rendered and can be painted without looking out of place, this will help, or several coats of transparent sealer if brick or stone.

 

[do_it_yourself]

cheers mate,

so the rain down the chimney pot is prob not the case?

more chance of it being penetrative damp? I suppose a few coats of sealer wont do any harm.

 

[do_it_yourself]

double post