Damp/Mould in Cellar after conversion

Just had our cellar converted we have painted the skirting boards and walls then noticed that mould hase started forming on both the wall and skirting boards.

Is this normal it seems to brush off but it smells and i presumed after paying for it tanking(membrane) we wouldn't have this problem.

Any help appreciated.

Andy.

Did you fix the skirtings with nails/screws, through the tanking system?

Hi Shytalkz

There are nails but i think they just go through the plasterboard the builders seem to have done a good job but then we noticed the 'green mould' type dust on the skirting and walls it dusts off but its the smell that worries me as well we dont want to keep painting the plaster as that i don't think will solve anything.

Andy.

If you have mould which brushes off, like you say, then you have a condensation problem.

If you had a problem with the tanking you would know about it

Cold bridges of the tanked walls and insufficient ventilation/circulation are the prime suspects for basements

Woody

whats the best course of action? the windows only have tricklers so i cant open them dehumidifier maybe or is there something else we could do.

Thanks

Andy.

Condensation is difficult to address. Have a read of the site FAQ on condensation.

Were the walls insulated?

If you have cold walls then you may face a losing battle. You need to heat the room to keep moisture in the air, and provide enough ventilation to circulate the air and prevent it from settling (condensing) on cold surfaces.

The exact specifics will be different for different rooms, so advice may be trial and error to see which works.

If you cant get any significant ventilation going, can't heat the room, and have cold walls, then I would look into a " Positive Pressure " fan system - this will pump air into the basement and around it and out through vents or the door.

These two come to mind, but there are others

www.nuaire.co.uk - Flatmaster
www.envirovent.com

You should be able to get a 60 day trial and a guarantee that they will (if suitable to the property) cure condensation problems.

As woody says, it's probably a condensation problem. Any conversion company worth their salt should know that ventilation is a key aspect of basement waterproofing. The standard for basement waterproofing (BS8102) gives 4 grades of dryness (see: http://www.cellars.co.uk/cellar-conversion.php)

1 Car Parking; plant rooms (excluding electrical equipment); workshops. Some seepage and damp patches tolerable.
2 Workshops and plant rooms requiring a drier environment; retail storage areas. No water penetration, but moisture vapour tolerable.
3 Ventilated residential and working areas including offices, restaurants, leisure centres etc... Dry environment.
4 Archives and storage requiring a controlled environment. Totally dry environment.

In a residential situation you are looking for at least a grade 3 environment which can usually only be achieved with ventilation.

It sounds like you employed a professional company to give you a dry basement. I'd say it would be reasonable to ask them to come back and install some ventilation/make good.