Damp patch on wall

[bobbarnes]

This is an exterior wall of a victorian terrace. The wall has been rendered and has a hair line crack that runs a good portion of its length and which has been there for about three years. The damp patch appeared about 3 months ago.

Any suggestions on fixing this? Does it need to be treated from outside and inside? Does the plaster have to removed down to the brick work on the inside and a seal applied?

It's only 12 inches square at the moment and only very very slightly damp. The colour change (light brown) is the worst aspect as we speak as its in a very prominent position on a magnolia wall.

A quick lick of paint in the room only covered it for about a week.

 

[marshman]

have you checked outside for lose pointing or a leaking gutter dripping on the wall.

 

[bobbarnes]

I shouldn't write things in a rush - don't think I explained this very well.

The exterior of the house has been completely rendered and this has the hairline crack.

The damp patch is showing on the interior side of this wall ie in our bedroom.

Just looked at it again and it's only a few inches across. I'm assuming it's coming though the crack and then the wall. In the past I've painted the crack but now it has opened up so I'll give it some another go although I presume this is not an "ideal" fix.

 

[jbonding]

has the rendering been recently done? if not it sounds like you might have a structural problem. is it above a window or door?