Can ventilation systems tackle damp in homes?

Damp in older buildings is often caused by an unawareness of how they are designed to work. Over the years the damp proof course can be built over or covered up outside, and on ground floors simply digging down against the outside wall(s), or chipping off roughcast covering the DPC, to reveal the damp proof slates or course can solve the issue. Injecting a damp-proofing chemical is usually a con.

Also in older properties, the inside of outside walls are often re-plastered with gypsum plaster which doesn't allow moisture to escape through the limestone mortar, whereas limestone plaster as originally used does.

And blocking up a chimney without a vent in combination with draft proofing is another problem!

Victorian 3 bed, solid brick walls. Windows all double glazed. Condensation and mould issue.
Yes, definitely support positive ventilation. Systems are now very quiet, operate in the background, also sense moisture (showering) and power up. We installed one in the bathroom and another to draw from the flat. The condensation and mould problem is gone. We took moisture content readings before and after. The content not really changed much, it is the air movement. We asked for a rent increase to cover the cost. The tenant very happy.
Installing these elsewhere, as yes landlords are the target for mould problems. We used Envirovent. There are others.

Reply to the comment left by TheMaluka at 27/04/2024 - 20:40
Doesn't that really only apply if they turn the heating down or off when they are using the dehumidifier?

Reply to the comment left by Beaver at 29/04/2024 - 10:53
The heating must be theromstatically controlled so any heat from all electrical appliances (fridge, television, dishwasher, dehumidifier etc) contributes to the overall heating of the property, the main heating source will just contribute a little less.

Dehumidifers are not best solution
both the bathroom and kitchen need extract fans -even if there are windows- these MUST exhaust the air to the ooutside so ducted in the kitchen is essential.

I am starting to put into my properties for the bathroom heat recovery units they a bit more expensive but as they reclaim the heat it encourages the tenants to leave them running longer infact in two of mine I have installed ones that run 24/7 at low speed with a humidity detector to raise rates when bathroom in use these units help the whole house and much more effective than mere dehumidifiers that tenants willl worry about the costs of running

If your tenants are complaining its hard if not impossible to heat the house/flat the problem probably is that there are draughts letting cold air in - pushing all the heat up to the ceiling but leaving the tenants with " cold feet" Check for draught especially under the front door/letter flaaps even light switches - get a candle and work all way round the flat yes even sockets etc

Reply to the comment left by blair at 03/05/2024 - 07:09
Which heat recovery units are you using?

We went to Positive Input Ventilation route. No more Condensation or mould. Envirovent, but there are others. I see Envirovent also do heat recovery

Reply to the comment left by Robert at 03/05/2024 - 10:30I suspect that because installing photovoltaics is just a box-ticking exercise from the perspective of EPC ratings, if you installed photovoltaics and it were possible to isolate the main electrical circuit from the positive ventilation/heat recovery ventilation system and use the PVs to power the ventilation system then the tenants would leave this on because otherwise they would receive no benefit. Anybody know if that is possible?

Reply to the comment left by Don G. at 28/04/2024 - 16:08
Your comment applies to stone-built properties using lime mortar. Even using midern vinyl silk or similar plasticised emulsion on the interior of outside walls is sufficient to prevent the walls 'breathing' in the way they were designed to. I learnt this the hard way in my own home!

As I understand Landlords are/have been made responsible for damp and mould. We sorted the condensation in 4 properties (Georgian, Victorian) with Positive Input Ventilation, placing one in the bathroom and another drawing from the property overall. They work quietly in the background all the time, or like in the bathroom, accelerate on sensing moisture. Result no condensation, tenants very happy, accepted rent increase to cover the cost. Done.