damp stains on first floor exterior wall

[plcanonica]

Hi,
We've never had a problem with damp stains on walls in the year and a half we have owned our home, but this January several have appeared on the external walls on the first floor. The stains are on the wall of the house facing southwest, and the walls are solid brick. The outside is rendered and painted (but I don't know what with). I can see a few tiny hairline cracks on the external render. Can these stains be due to the large amount of rain over Christmas wetting the wall? Most of the stains seem to be below windows too. The windows are old, and the external wooden windowsills are fairly rotten as well. Could these have become soaked and helped the wet penetrate the wall?
What solutions do people suggest both to re-paint, and to prevent the problem in future?
Thanks,
Paolo.

 

[Chri5]

Sounds like the sills all need replacing, sometime you can get away with chopping areas out with a multitool and fabricating hardwood infills to replace the areas pulled out.

If water is sitting on rotten sills there's a good chance the water will find itself getting under the sills and in to walls.

 

[Chri5]

You could over clad the sills with PVC sheet and sealant, but that is a bit rough depending on your standards.
I tend to want everything original, not everyone does or cares about such stuff.