Damp room under stairs

[themoo]

I would be grateful for any advice on how to handle this. It's an unventilated little cubby hole under stairs and the damp gets bad as you can see from the black mould which I cleaned off a couple of months back.

It gets flooded when the rain is really bad, but I've put sandbags up which helps hugely. However this does seem to make the damp even worse! I've got a dehumidifier in at the moment.

The porch outside has an air brick in it so if I put something like that in will that do the trick?

I would really like to sort it out.

Thank you!

 

[endecotp]

It's an unventilated little cubby hole under stairs

Those are external stairs, right?

Does it open into the porch, or into the inside of the house?

It may be unrealistic to expect it to be dry.

 

[themoo]

Thanks for your reply. Yes, they are. It opens into the porch. I was wondering if a ventilation thing / airbrick like the one in the porch might help.

 

[endecotp]

If it were mine, I'd probably only try to store wet / outside things in there, e.g. that mop, wellies, gardening things etc.

I suppose a vent might help a bit, but the surfaces are always going to be cold so any moisture is inevitably going to condense.

Taking the door off, so it is just an alcove in the porch, would also increase air circulation.

 

[themoo]

Thanks. That is really helpful. I could take the door off, and if it doesn't make any difference, I could put it back on. I was also thinking about putting a dehumidifier in there - one of those rechargable ones which you just have on all the time. I've got boxes with damp crystals in there which do make a difference.

 

[Paulintheprocess]

From the pics it looks like a mix of water ingress and trapped moisture. The sandbags stopping flooding help short term, but they also stop airflow, so the space never really dries out, which is why the mould keeps coming back.

An air brick or vent to the outside could help, especially if it gives cross ventilation, but it won’t fix active water getting in. I’d be looking at redirecting water outside first if possible, even a small channel or better fall away from the doorway can make a difference. Inside, keeping that area clear, running the dehumidifier after heavy rain, and using mould resistant paint once it’s fully dry can help manage it. Long term, ventilation plus stopping the water at source usually works better than sealing everything up.

 

[themoo]

Thanks so much for your insight! The building is in a bit of a "dip" if that makes any sense (will take a photo) so I am not sure how to divert water away as it gathers in a little channel at the base of the building. I didn't know you could get mould-resistant paint but I will be investing; stupid question but can that go directly onto the walls as they are or do I have to clean all the mould off? (I clean it regularly but the bits you can see on there are stained)