Newly converted cellar and damp

[Bluestar23]

Hi,

We have just had our cellar converted.
It is unusual in the fact that we have 2 terraced houses joined together.
This means to get from one cellar to another a doorway was created.
This has been there since I moved in over 20 years ago. I always used the first cellar for storage but never the second as there wasn't a light in there.

The configuration is stairs down into the first cellar.
Then the doorway was made into the second cellar coal storage so it's a small passage into the second cellar.
These are 2 bed terraced houses joined together so they're really not massive!

It's never been more than a little damp down there in all 20 years so we've had it tanked, a small window in the furthest cellar, fan inbetween and a further fan in the first cellar.
We didn't feel the need for a pump due to the lack of water.

The main work was completed in the cellar in February by a local company who have a proven record of conversions.
We've then painted, joiner has put in skirting board etc, one side has a vinyl tiles and the other has just had the carpet laid.
There is electric heaters in each room.

And now we're essentially done it feels that there is an issue with air flow as we are getting some slight patches of damp on the walls in the second cellar . It's from the room as it's on surfaces rather than the fabric of the walls. A white fuzzy covering in particular areas of the basement.
We've put the dehumidifier down there and it's registering over 80% humidity which is higher than when it's in a room with wet washing!
The carpet is dry and there's no visible wetness.
There doesn't appear to be any issues in the first cellar.

The first cellar has a solid floor and there was a chest freezer. It was one we've had for years down there and we realised it was leaking so it was removed a week ago. Floor wiped dry and all fine.
The condenser drier is also down there but we've not been using it as we only really do in Winter.

Any suggestions please!

If you only removed the leaking freezer a week ago you need to dry it out. You can get drying products, dehumidifier, heaters, they need to run 247 for a while. Also you can buy gel/crystal things that can help.

Put in the dehumidifier. A lot of people have them in above ground rooms. My son put one in his flat because of the drying washing issues. Cellars are problematic too.

Tanking it might be trapping the moisture in now, whereas before it was 'breathing' (if it's an older house they need to breathe).

You've created this problem by tanking (I assume this involved concrete) and putting down vinyl tiles and other non-breathable materials.
Victorian houses need to breathe, especially in cellar rooms. Think: bare bricks with lime mortar; lime plaster; exposed brick, flagstone or terracotta floors. Breathable materials only.
This group might be able to help you: https://www.facebook.com/share/JEy1oRodXVFNWgA8/

Okay, so it seems that by trying to create a dry space we've made it worse!

Looks like we're about to enter into a lengthy battle with our cellar to keep it usable as extra family space.

The first cellar seems to be fine so far.

The dehumidifier is already down there but only in one side. We were using the spare bedroom as the 'drying room' for washing and wanted to move it down there. Which may not work quite as we planned.

Thank you for the feedback.

We haven't tanked our cellar for this exact reason, that we are worried about it stopping the building breathing

This might explain what is happening and why https://www.kezzabeth.co.uk/2020/11/why-your-cellar-walls-need-to-breathe-and-why-were-not-tanking.html

The more I read the more I think 'oh dear!' face-palm.
Our house isn't big, posh or worth much money but we have made so many changes to the house.
When I bought it in 2001 as a 21 year old it was very badly converted from 2 to 1 house with 2 sets of stairs (1 unused) , blocked steps to the 2nd cellar to create a cupboard, front door straight from street into the kitchen odd configuration upstairs with walls put up badly.
So over the years we've removed stairs, changed the cellar cupboard to a downstairs toilet, had a loft conversion and finally the cellar conversion.
I have a feeling all of our changes rendered some of the original purpose of the design of the houses.
Many years ago there was government funded damp proofing work in the area which blocked air bricks up. I was about 25 I reckon at the time and had no idea what issues I was causing!
So to be fair we've caused more issues but my poor house was probably already there in that respect.
We don't have many issues but have to be mindful air flow around windows, curtains etc