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Is a damp patch on the exterior surface of a brick wall a cause for concern? its on the extrior of the flat below mine. it on the wall where there was once a chimney breast long removed. (we looked at both flats and went for upstairs one the wall has a patch that looks like its had some work done before (black mortar) should i be concerned?

If it is on the exterior then I'd be wondering how the damp patch got there?

Is there a broken gutter near by or a blow off pipe for a boiler perhaps?

its on the gable end roughly circular and at person height no boiler near, or gutter could be wind blown i guess just an odd shape.

big bruv wrote:its on the gable end roughly circular and at person height no boiler near, or gutter could be wind blown i guess just an odd shape.

There are actually 3 damp patches that appear to be around and near air bricks, would this be warm damp air condensing on the cold exterior having escaped from the wall and condensing on the cold bricks? perhaps the reason for the air bricks?

Any chance of some pictures?

ultimatehandyman wrote:Any chance of some pictures?

Will try tomorrow too dark now the patch is about 3 feet high and 2-3 wide it was larger earlier so seems to have shrunk

Hi, I made it!
If its a solid wall?
Then you have two possibilities.
One, the rain has made its way through the wall and made it cold and damp, leading to interior condensation, usual thing cold internal wall attracts water vapour in room, water vapour condenses into wall and makes its way outwards towards the cold arriving at surface.
Two. Air bricks are making the surrounding wall very cold and internal water vapour is settling as above.
As far as you are concerned, nothing to worry about.
But, keep an eye on it, see if it disappears when the spring comes.
If you know the people have a word, they may not have noticed, or may have no idea what to do.
Probable best solution if penetrating damp, three coats of silicone paint to shed the rain.
If vents are not to provide air to a boiler, fire, hob or something then block them up, have a warmer room at less cost.
Perry

THe patch is mush smaller now its warmed a bit i think the vents are there to cure a previous problem there is an injected DPC and 4 air vents on the wall I think the wall is solid ie no cavity but its the gable end of a row of terraces so it must be double brick thick? I'll keep an eye on it hopefully nothing to worry about just never seen anything like it before

Its really quite common, used to happen a lot years ago before builders started using cement. That's why cavity walls became popular.These days due to using mortar that's gone off.
Perry

big bruv wrote:it on the wall where there was once a chimney breast long removed.

Is the chimmney properly sealed? or has the stack been taken down below the roof level?

gib_goblin wrote:

big bruv wrote:it on the wall where there was once a chimney breast long removed.

Is the chimmney properly sealed? or has the stack been taken down below the roof level?

WE had the unused flues capped about 9 months ago 4 flues 3 are capped and 1 has a gas cowl (used for kitchen extractor hood) it could be years of rain slowly coming out. it does seem localised to the air bricks vents so hope its nothing serious.

Hi new on the forum.

I have similar problem. The Damp patch seem to be getting bigger over past few years. It is near the roof and the pipe (drainage not the gutter drain) vent. I also have flu of the boiler 'poppint' out further to the top of the roof, but in the same line as th damp patch. I have the gutter cleaned regularly.
The damp patch has now reached the height of the bathroom window of my semi-det.

Any suggestion is greatly appreciated.