Damp

Enaghan01

I am renting out a house that was built in 1986 and recently it's starting to show signs of damp. It's causing me a lot of grief because I try to be a good landlord and this is 1) a health hazard and 2) just looks bad. It is a detached dormer with insulation in the cavity walls, feck all insulation in the roof. There is no ventilation in any of the rooms except an extractor fan in the kitchen and bathrooms. The only room that does not show any damp is the one with an open chimney in it. This leads me to think that ventilation is the problem but that's just a guess on my behalf. I'd like help with two things.

1. Any general advice you can give

2. Are there any experts that I can get to look at this? I understand that I would need to pay for this but if they can guarantee to fix it for me, I think that it would be worth it

Kashkai

For a start, try putting in vents in all the rooms. It'll mean drilling through the walls but this should have been done at the time the house was built (although I had a friend whose builder just screwed vents to the internal walls without actually putting a hole through to the outside).

Open the windows as much as possible to let air flow through the house.

Get a dehumidifier to suck the water vapour out of the furnishings.

Don't let (or at least try) tenants dry clothes on radiators

If these don't work, then perhaps your problem is more serious like a leak somewhere or even a defective damp proof course.

Enaghan01

Thanks Dave, I was thinking I will have to try that and see what happens but I didn't just want to put a hole in the wall either. I hear there are clever vents that open up when the humidity reaches a certain level, they open to allow warm air out and cool air in. Does anyone have any experience of using these?

RKQ

Prosperous Dave is correct.
Why not try the least evasive options first i.e use a dehumidifier to suck the water vapour out and prevent tenants drying clothes on radiators.

If there is a visual improvement then the problem is caused by condensation and a lack of proper ventilation.

Have your considered investing in a Heat exchanger and ventilation system?
It might be a good option. Naturally you should also greatly increase attic insulation levels.

I've seen wall vents that can be closed in the vent but theses are expensive. Drilling 100mm dia. holes is easy enought but will involve filler and painting.

Enaghan01

Yeah, I would consider mechanical heat recovery ventilation (I think that's what you are suggesting) but the house is not airtight so I'm not sure about how good this would work for me. Would it just be pumping out hot air and driving up the gas bill?

Also, cost is an issue. I've seen quotes for 10 / 12 grand, can't really afford that at the moment. I was hoping that individual vents in each room might work out cheaper. I had read about individual vents that have a heat exchanger in them but don't know how well they work or if there is anyone in this country to ask.

It's very hard to get impartial advice

RKQ

Enaghan01 wrote: »

. I was hoping that individual vents in each room might work out cheaper. I had read about individual vents that have a heat exchanger in them

I'm getting confused as you said earlier you didn't want to drill holes!
Airtightness is not the issue - an airtight house must have a mechanical heat recovery ventilation (MHV) unit because it has no natural ventilation - because its airtight!

An ordinary house can have a MHV unit. The mechanical heat recovery ventilation takes away warm stale air and pumps in clear external air. Ideal for removing condensation. This fresh air is heated on the way in by the heat from the old stale air, in the exchanger.
It has nothing to do with airtightness.

The quotes you got seem high. I'd get 3 reliable quotes.

Enaghan01

Ok, I was under the impression that a house had to be airtight before you could install a MHRV unit but what you say makes a lot of sense. It would be ideal for my purposes. I must look around at the weekend. Do you know of any examples of people who have retro-fitted a MHRV to an existing non-airtight house?

Millie

I have a problem with dampness on one wall in my bathroom.
So am I better to have the window open as much as often or try and keep the heat from the rad in to help???

RKQ

Millie wrote: »

I have a problem with dampness on one wall in my bathroom.
So am I better to have the window open as much as often or try and keep the heat from the rad in to help???

If its condensation - leave a window open slightly during the day. Close the window at night and let the rad continue to dry out the room. Open the window when you use the shower / bath - or immediately afterwards.

Has the bathroom got an external wall vent?

If its severe condensation, then a mechanical ceiling extractor fan will help.

Depending on which wall is wet and where its wet, it could be a leaking pipe.

Millie

Thank you very much!