Cellar damp/ mould issue

[bunters1976]

Hi

Short version - moved into new house with a cellar (one main section and then a small further section with outside wall). I believe it was an old coal a cellar.

Upon purchasing house appeared fairly dry. Took advice and bitchumen painted the walls to hopefully create a dry usable space. This was approx 8 weeks ago.

Since then there has been a lot of damp especially on the smaller section with the outside wall. In there the room has gone really mouldy on all walls but not the ceiling. There is some drains on the other side of the outside wall but

I left a dehumidifier on and it filled a builders bucket in 2 days and was still going.

There is no ventilation as the original chute has been boarded up so I was thinking maybe condensation could be an issue but seems an awful lot of water?

I have added some photos.

If anyone has any ideas or advice that could help, that would be much appreciated.

Thanks

 

[flameport]

Painting walls and running dehumidifiers in a underground cellar will achieve nothing.

All cellars are damp and mouldy.
There are ways to convert them into usable rooms, but this will be thousands of pounds at least, five figures would not be unheard of.
Most people have better things to spend their money on.

 

[bunters1976]

When I said useable... I meant as storage and not covered in mould. Is this possible without spending a fortune?

 

[EFLImpudence]

Is this too obvious?

 

[DaveHerns]

It would make an ideal coal cellar!

 

[bunters1976]

The waste pipe for the sink was leaking causing the water on the outside on the photos. Fixed that but still have approx 2l every day from the dehumidifier. Seems very strange as it's been so dry.

 

[IWalkLikeHimaMartian]

The waste pipe for the sink was leaking causing the water on the outside on the photos. Fixed that but still have approx 2l every day from the dehumidifier. Seems very strange as it's been so dry.

2l of water per day from any above ground room would be about average.

 

[bunters1976]

O OK. So potentially no major issues then. Thanks I didn't realise that

 

[IWalkLikeHimaMartian]

Run your dehumidifier in an average above ground room for a couple of days for comparison.
Keep the windows closed.

 

[mattylad]

Ventilate the room, it will improve.
If your going to store stuff in there ensure it is well wrapped up in sealed containers.

Stuff in my cellar is ruined because I didn't...

 

[Doggit]

Cellars are strange places. They were never intended for serious storage of anything that couldn't handle moisture, so were never designed with any consideration.

Unfortunately, you've painted the bitumen on, so you can't determine if, or where, the damp areas are. The floor very likely doesn't have a dpm in it, and the walls will have earth behind them, but if you're lucky, it's dry earth, and so will the walls be.

The cellar will be colder than the upper floors, so the 2ltrs per day may well be normal, and you just need a low power fan at one end to take create an air flow, and take the moist air out.

But if the floors and the walls are damp, then you'd need a liquid dpm on the floor, and a simple screed on top of it, and another coat of bitumen on the walls, then sharp sand on top of it before it dries, then you can put a couple of coats of waterproofed cement on top of it.

Anything beyond a simple fix, will as Flameports has suggested, cost a great deal more.

 

[IWalkLikeHimaMartian]

Ventilation can help, if it is a steady airflow over the surfaces. If it is not, it will only work if you are doing other things in conjunction.
If you are replacing air in the cellar that is about 75%RH, with air from outside that is about 85%RH, without warming the air in the cellar, that ventilation is not only pointless, it is counterproductive. It is why empty, unheated houses suffer from damp in all rooms. It is not because all the walls are leaking.
Ventilation works when you take in air from outside that is probably about 85-95% RH, and warming it up to lower the RH, and to increase the capacity of its moisture retaining capabilities. Then expelling that warm air with its extra retained moisture. Repeating the cycle ad infinitum.

If the air that you bring into the cellar is from the other living areas, it will usually be warm air, but with an RH of about 60-75%.
Introducing that into the cellar, to cool down (and lose some of its moisture retaining capacity), and the result is obvious.

As I posted sometime ago, take a cold glass of beer and watch the moisture form on the outside of the glass. I can guarantee it is not because the glass is leaking!

Mold caused by damp on cellar walls is often through condensation caused by the moisture in the air, in contact with the colder walls and floor.
Ventilation and heating can reduce that condensation/damp/mold. So can dehumidifiers.
As I posted, and subsequently deleted (you can thank woody), over a period of time condensation will lead to the walls/ floor absorbing moisture.
It will take another period of time, using ventilation/heating or a dehumidifier, to reduce the moisture in the air, and subsequently in the fabric of the building.
It is why buildings that have been flooded take so long to dry out. It is not just the air that needs to be dried. But the only way to 'suck' the moisture out of the fabric is to dry the air.

Think about damp timber, and how that timber is dried, over time. Or what happens to it if it is allowed to retain that moisture. (excluding the use of a kiln. You cannot put the building into a kiln!)
Think about corners, spaces in subfloors etc that do not get a sufficient airflow.

If you are using a dehumidifier, you do not want ventilation.