Damp patches on outside walls

sclare

I've just noticed large damp areas on the outside of my house, on two adjoining walls. Does anyone know what might be causing these? And what do I do next? There is a downpipe atthat corner but I don't know if it's to blame or if the damp is coming up from the ground. 
In the second photo, the patch stops at the top of the photo, and in the first it stops just before the upstairs window

MikeJXE

Over flowing gutter ?’

sclare

MikeJXE said:

Over flowing gutter ?’

World the patches not go all the way to the top of the wall if that was the case? I'd love of that was the reason, as it'd be quick to solve. 

It shows no sign of drying out though after yesterday's dry and sunny day

Albermarle

Overflowing gutter - if it overflowed on the external edge then it would tend to effect the lower part of the wall .

Also the weather has been very wet and if the wind was blowing a certain way it could have soaked the walls ? Just a guess?

MikeJXE

Simple to solve, have a look next time it rains 

sclare

Thanks all. My neighbour has just reported that he saw water gushing over the top of the guttering during the heavy rain, so we have confirmation. I'm glad it's something simple to resolve!

FreeBear

The shrubs will slow down the rate the wall will dry out. Quite possible the shrub roots have got inside the underground pipe and are the root cause of the blockage.

If you haven't got one, I'd recommend fitting a debris interceptor gully at the bottom of the downpipe. It will trap crud coming off the roof and give you an access point to rod out the underground pipe. Although, if you need a P trap, you won't get drain rods down, just a drain snake.