damp on interior walls

[treesntrees]

What can I do about damp and mould on interior walls of mid terrace house. I had damp penetration on exterior walls treated and this seems to be effective and there don't seem to be any leaks to account for the damp. I know the tenant takes pride in keeping the new central heating at a low temperature (understandably) and I think he is taking my advice about leaving the window open a crack in the room where he dries his laundry. I have provided him with clothes horses so he doesn't use the radiators and there are two extractor fans in the kitchen. The only thing he doesn't do is open his curtains in rooms he isn't using. Is there anything else we can do?

Are the windows open every day? When he dries his laundry is the window only open a crack? The windows need to be regularly open and open wide, even in colder weather. Most mould problems are due to tenants simply not heating or ventilating properties sufficiently. Does the bathroom have an extractor fan? Does the flat have a tumble drier? Perhaps he could buy a dehumidifier and run that to keep the moisture content down. If you think about how much water comes out a tumble drier if you just dry e.g. a duvet cover it's not surprising that opening windows a crack simply isn't sufficient.

When you ask what YOU are going to do about the problem, I think the question should be what is HE going to do about it?

Wet washing draped around a house is like throwing buckets of water at the walls.

If the occupant won't use a tumble drier or a washing line, the home will be wet.

If the bathroom has an extractor fan, washing can be hung over the bath with the door and window shut and the fan running. A typical extractor will run for about 50 hours on 12p worth of electricity, so cost is not a reasonable objection.

If the fan is worn out and noisy, get a new one with a ball-bearing motor. Some very good fans are now available.

Piglet I will suggest he uses the bathroom for drying. The fan was put in two and a half years ago and is pretty quiet. I know he is concerned about costs after running up debts years ago during a Psychotic Episode. He has started using the outside line when it is not raining so a small step.I have also advised him to move a bookcase and a settee away from the damp walls. I doubt if he would use a tumble drier even if there was room for one.
Unexpected I didn't want to invite attacks from the Landlord haters by asking what the tenant can do. He has been my tenant for four years now and I have seen quite an improvement in his mental health. He now asks for advice with regard to what he can do to address property issues and pays his rent on time so I try to help him all I can as to my mind he is a good tenant.

Could you get him a dehumidifier? To run one of those with a drying tent for washing would be fab...

random he is very concerned about his electricity costs so I don't see him being willing to use one of those. Thanks though.

OP, I think you are obviously a very good landlord and you don't want to upset the tenant's mental equilibrium but you need to find some way of making clear to him that ultimately mould and damp problems will be at his expense (as they are caused by his actions not by any structural defects in the house). The cost of putting those right at the end of his tenancy could far outweigh electricity costs over a period of time, to turn up the heating or run a dehumidifier.