Dampness

[Troll]

Well that looks quite clever.

I guess only a professional will be able to fit that.

Looks a simple enough device - if I read that correctly it's pulling in air from a vented loft space and pumping it into the stairwell to aid circulation - can't work out if the wall units are powered but assuming they are:

Negatives

• need to check your loft ventilation is OK
• You're pumping in cold air and extracting warm air to the outside - expensive in the winter
• Need to check the noise level of the unit esp. if running through the night

But installation looks within the capabilities of a comptent DIYer

[xoggoth]

Hygroscopic cement? Maybe pointing needs redoing or cover with some moisture resistant stuff.

Technically a 'dry' wall could be regarded as one that is not subject to active water ingress; in other words it doesn't contain free moisture. However, in practice, it could be damp solely due to hygroscopic moisture, ie, water that is solely being absorbed from the atmosphere.

Distribution of Moisture and Soluble salts

[wurzel]

Appreciate the info.

Couple of follow up questions:

1) Did Peter Cox charge to come out and assess your problems?
2) You say you are going to install the extractor yourself - did you buy the unit from Peter Cox or do you know of somewhere else to get one? If so, do you have a link and is it just a case of an electrician being able to install it?

1) No, it was free of charge
2) Haven't bought the unit yet. Their quote was for an Envirovent Humidistat Filterless Extractor & all the electrics plus core drilling through a 2.5 foot wall for the outlet pipe. Seems it can be bought for less than £200 quid link