What's causing this?

[SirGalahad]

There is damp, condensation forming on the outside wall around an air vent that sits under the kitchen. The kitchen floor is above the air vent and the vent is accessible via a hatch in the cellar.

 

[Madrab]

Don't mean to be ignorant but no-one on here will be able to tell you, it's an impossible question to answer without being there. If there isn't anything obviously leaking onto the wall internally then unless there's something above it that is leaking down onto it then without being there it would be impossible to tell.

 

[GoodDIYjob]

IS this the same wall as this post.

What's causing this?

There is damp, condensation forming on the outside wall around an air vent that sits under the kitchen. The kitchen floor is above the air vent and the vent is accessible via a hatch in the cellar. The sink is directly above that.

www.diynot.com

From both photos it seems most likely to be condensation, especially as it seems to taper out towards ground level. Extreme cold air meeting warmer (moist air) condenses around the air vent. Is there cross ventilation under the floor, i.e another vent on another side, is it damp under there humidity wise. You said you run a rad in the cellar?

Edit: Assuming no plumbing fault, leaking drain or gulley or water service pipe or sink....

 

[SirGalahad]

IS this the same wall as this post.

What's causing this?

There is damp, condensation forming on the outside wall around an air vent that sits under the kitchen. The kitchen floor is above the air vent and the vent is accessible via a hatch in the cellar. The sink is directly above that.

www.diynot.com

From both photos it seems most likely to be condensation, especially as it seems to taper out towards ground level. Extreme cold air meeting warmer (moist air) condenses around the air vent. Is there cross ventilation under the floor, i.e another vent on another side, is it damp under there humidity wise. You said you run a rad in the cellar?

Edit: Assuming no plumbing fault, leaking drain or gulley or water service pipe or sink....

Yes the same post - not sure why I posted twice, can mods merge posts.

There is no plumbing fault as none of the pipes run next to the wall, there are droplets on the wall - like dew collecting.

The cellar runs the length of the property front to back. At the front of the house at cellar level there are 2 brick vents to let in air and in the back there is a coal chute so there is air flow. This is access under the kitchen, I have left the trap door open. Not sure how to resolve this if its condensation.

 

[SirGalahad]

IS this the same wall as this post.

What's causing this?

There is damp, condensation forming on the outside wall around an air vent that sits under the kitchen. The kitchen floor is above the air vent and the vent is accessible via a hatch in the cellar. The sink is directly above that.

www.diynot.com

From both photos it seems most likely to be condensation, especially as it seems to taper out towards ground level. Extreme cold air meeting warmer (moist air) condenses around the air vent. Is there cross ventilation under the floor, i.e another vent on another side, is it damp under there humidity wise. You said you run a rad in the cellar?

Edit: Assuming no plumbing fault, leaking drain or gulley or water service pipe or sink....

I run a dryer in the cellar but that vents out via the coal chute.

 

[GoodDIYjob]

Yes the same post - not sure why I posted twice, can mods merge posts.

There is no plumbing fault as none of the pipes run next to the wall, there are droplets on the wall - like dew collecting.

The cellar runs the length of the property front to back. At the front of the house at cellar level there are 2 brick vents to let in air and in the back there is a coal chute so there is air flow. This is access under the kitchen, I have left the trap door open. Not sure how to resolve this if its condensation.

Ok. Is it only now, with extreme cold that the problem has arisen? Does it go away?

I run a dryer in the cellar but that vents out via the coal chute.

Ok. Have you checked that the hose is intact and exhausting all moist air to the exit of the chute?>

Edit: Q3) how saturated is that ground under there near the wall with the carpet and where is the DPC level in brickwork? Top of the vent probably? Is there a DPC evident.

 

[SirGalahad]

Ok. Is it only now, with extreme cold that the problem has arisen? Does it go away?




Ok. Have you checked that the hose is intact and exhausting all moist air to the exit of the chute?>

Yes not seen it before. It's definitely more noticeable now during the winter.

The hose is intact and there is possibly some air escaping. I have a small window in the cellar - would opening that during the day help or will that just bring in more cold air?

 

[GoodDIYjob]

Yes not seen it before. It's definitely more noticeable now during the winter.

The hose is intact and there is possibly some air escaping. I have a small window in the cellar - would opening that during the day help or will that just bring in more cold air?

Mmm. yes ok.

The window. You could definitely try to open, for some more air exchange. And assess what happens. Closing for late afternoon / evening/ night time. See if it improves at all with the air exchange. The air will be colder but may be dryer than the air in the cellar.

A hygrometer, to measure humidity may help as well to understand how damp the air is. On my #6 Q3) i added some questions which will have missed your reply.