damp cellar in house thats been unoccupied - possible remedies

Suekeendiyer

I have purchased a flat that has a decent sized cellar. Cellar has been tanked in the past but is now showing signs of damp. Smells damp, there is mould on some of the walls, but the concrete floor and ceiling are both dry, and the walls are not wet to touch even after rain.
Having read a lot about how difficult it is to get a truly independent damp survey I was wondering if it is worth trying some low tech remedies first to see if it is a problem caused by the place being unoccupied and unventilated for 7 years.
I was going to firstly put a dehumidifier in the cellar, and let it run for some time, and also strip off the existing wallpaper then treat the walls with a good quality mould killer. At the same time leaving windows on ground floor open to allow airflow. I might also at this stage install a window fan to increase air flow as that will not cost much.
I am renovating the rest of the place so there is time to see if these measures work. Does anybody have any further advice on what to do.
The property is an old style terraced house that has been converted into flats. There is no sign of damp anywhere on the ground floor.
I am wanting to use the room as a games/tv room partly to prevent noise disturbing occupants of first floor flat, and also partly to allow more space on ground floor for kitchen/dining area.

FreeBear

A cellar should have several air bricks around the perimeter to allow air to pass through. A dehumidifier will help to reduce the damp temporarily, but long term, you need to fix the ventilation.

konark

A window fan would improve ventilation/ airflow.

Doozergirl

Cellars are supposed to be damp. Unless the previous owner spent a small fortune properly converting it to building Regulations standards (which it sounds like they haven't) then it is a damp cellar, not a TV room.

You have a lack of ventilation down there. As Freebear says, you need airbricks in there. If you have a wooden suspended floor, the joists will be susceptible to rot. The joists need to breathe, particularly, so cladding the ceiling in plasterboard isn't a great idea.

bxboards

I have a house with a couple of large cellars rooms and that can often have a musty smell, although its never wet inside as such. It was built circa 1780-ish in what would have been in the merchant's quarter of the town - that cool slightly damp area would have been ideal for storing food and other goods that might have perished pre-dawn of the invention of refrigeration.

So the dampness is normal really, these were never designed to be a habitable space.

An extractor fan can really help with the mustiness, and if your property is old its likely not have have airbricks. I've not sure if its practical to retrofit these? I'd see if you can fit a fan just below pavement level, it will need to be much heavier duty than a bog standard bathroom extractor fan.

They are techniques to turns cellars into habitable spaces, usually involving a membrane (Newton / Platon) etc and studwork. You might also need to consider how to remove any water that may enter behind the membrane, which would end up being trapped if you did this.

I'd look at ventilation first.

Doozergirl

It's entirely practical, and cheap, to retrofit airbricks.

It's also pretty unusual for an older house not to have airbricks because the joists will rot and the house would really suffer if it didn't. They were designed that way. It's far more common for them to have been blocked up by people who didn't know what they were doing.

bxboards

Doozergirl wrote: »

It's entirely practical, and cheap, to retrofit airbricks.

It's also pretty unusual for an older house not to have airbricks because the joists will rot and the house would really suffer if it didn't. They were designed that way. It's far more common for them to have been blocked up by people who didn't know what they were doing.

Even if the cellar area is entirely below ground? I'm struggling with this one a bit, as even if some of the existing cellar walls were replaced with an airbrick, I'm not getting how you'd get air circulating from the earth / soil etc outside.

Not dis-agreeing, just curious how an airbrick is going to work if you are below ground level in a cellar?

A year or two back I looked at loads of places with cellars, and the 'walls' of the cellar were constructed pretty much like you'd see a stone wall down a country lane, some you could barely stand up in, others had flights of stairs. But I don't recall seeing airbricks in any of them. One had some chains and manacles embedded in a stone which was a bit creepy, and another had a sump pump which must have been fitted years later.

Doozergirl

bxboards wrote: »

Even if the cellar area is entirely below ground? I'm struggling with this one a bit, as even if some of the existing cellar walls were replaced with an airbrick, I'm not getting how you'd get air circulating from the earth / soil etc outside.

Not dis-agreeing, just curious how an airbrick is going to work if you are below ground level in a cellar?

A year or two back I looked at loads of places with cellars, and the 'walls' of the cellar were constructed pretty much like you'd see a stone wall down a country lane, some you could barely stand up in, others had flights of stairs. But I don't recall seeing airbricks in any of them. One had some chains and manacles embedded in a stone which was a bit creepy, and another had a sump pump which must have been fitted years later.

The house above comes out of the ground. DPC should be two brick courses above ground level and joists should sit on. The joists of the ground floor simply have to be above ground level or they'd rot.

Sometimes the celaars can be vaulted with bricks over but I've seen holes with retaining walls dug against the walls to enable decent airflow through those.

Ventilation is essential in all houses. I think if you've been in cellars that have no airbricks then they've probably been blocked up or a modern system of managing ventilation has been put in cellar conversions.

trailingspouse

Personally I wouldn't waste money on a damp survey. You know that the cellar is damp, in fact it sounds like it's very damp - what is a survey going to tell you that you don't already know?

Soulginge

A continuous running extractor fan may be the way to go, something that is always drawing air through the room. You may even want to look at one that retains the temperature in the room by drawing slightly heated fresh air in while extracting stale air out.