Damp patch on external wall

[NathanBenn]

Hi Guys, I’m looking for some advice or what to do with the the below;

I’m having trouble with wetness/condensation around the air vent on my external wall in my hallway. The cavity wall has got insulation in it.
If I close the vent or open it I still have the same outcome and it’s starting to spread more around on the wall. Any advice on what I should do .. Can I block it up has it’s at the bottom of my stairs which is an open space? I have a window at the top the stairs which can be open for airflow.
The house is semi detached and the wind and rain hits this side of the wall where the vent is located (also wall is rendered and pebble dashed).
I have the same vents in my porch but don’t have the problem I have here in my hallway.

We recently moved in and the person who had the house before us had wallpaper on the wall and didn’t seem to have a problem and was a family members house so seems to be a new or existing problem only noticed since the winter months.

should I change the outside vent so stop
such breeze coming in from the wind?

any advice is much appreciated as unsure what to do.

 

[JohnD]

Stand back and take a wider pic of the corner, including both walls.

Also photograph the outside. Both entire walls. All the way up to the roof and down to the ground, including the gutters, downpipes, drains, manholes and paving. Outdoor taps, hosepipe and plumbing overflows. Porch roof and gutters.

Find and indicate on your photos the DPC. How high above ground or paving is it? Has it been buried, paved or rendered over?

Is the floor concrete? Where are the internal and external stopcocks?

BTW
Ventilation does not cause damp.

 

[NathanBenn]

Hi John,
Thanks for replying to my post!
I’ve attached photos of inside floor to ceiling and outside. DPC I believe is on show underneath the render..

 

[NathanBenn]

Stopcocks are located outside of drive and under kitchen sink. We just had these renewed as we done a full renovation in the house

 

[JohnD]

It'll be the downpipe, I think. Probably a leak, blockage, spill or splashing. Might be the gulley. The rainwater goods are very amateurishly put together and look unsatisfactory. I suspect the airbricks were added in an attempt to dry out the damp caused by the poor build.

Take some closer pics.

Relevance of the stopcocks is that the water pipe will run between them under the floor, and if leaking will cause damp, often in the hall.

 

[Koolpc]

No need for a vent (unless you have a gas fire etc). Take it out and make good.

 

[JohnD]

Sadly the rendered wall looks damp at the foot all the way along, and has been painted black at the plinth, usually a futile attempt to hold back damp. It might be that the concrete slopes to hold rain against the wall, but the dpc may well be bridged by the concrete raising higher than original ground level and there may be problems with drains leaking in the ground.

Search for the dpc. It might be visible beside or below a doorstep. Once you have found it, it will be at the same height all round the house. In a semi it will be the same as your neighbour's.

Do not allow anyone who sells silicone injections or ceramic tubes near your house.

 

[NathanBenn]

Stand back and take a wider pic of the corner, including both walls.

Also photograph the outside. Both entire walls. All the way up to the roof and down to the ground, including the gutters, downpipes, drains, manholes and paving. Outdoor taps, hosepipe and plumbing overflows. Porch roof and gutters.

Find and indicate on your photos the DPC. How high above ground or paving is it? Has it been buried, paved or rendered over?

Is the floor concrete? Where are the internal and external stopcocks?

BTW
Ventilation does not cause damp.

Sadly the rendered wall looks damp at the foot all the way along, and has been painted black at the plinth, usually a futile attempt to hold back damp. It might be that the concrete slopes to hold rain against the wall, but the dpc may well be bridged by the concrete raising higher than original ground level and there may be problems with drains leaking in the ground.

Search for the dpc. It might be visible beside or below a doorstep. Once you have found it, it will be at the same height all round the house. In a semi it will be the same as your neighbour's.

Do not allow anyone who sells silicone injections or ceramic tubes near your house.

Thank you, just to mention when I took the vent off lastnight I didn’t notice any wetness inside on the insulation in the cavity or on the bricks just on the internal side of the wall and the vent cover would be moist with condensation just thought I’d say if it’s releated. I’ll check the down pipe out and clear the drain just to make sure it’s flowing correctly

 

[JohnD]

I think most likely the water is coming from the downpipe arrangement, and will dry out once fixed. I wouldn't spend time on anything else yet.

Photograph the gulley. It might be brown glazed clay, liable to crack. Look for any signs of cracks, repairs or sinking.

 

[NathanBenn]

Thanks John for all your advice, I appreciate it!
I’ll look into the gulley!