Damp, condensation and PIV units

[Deleted 198600]

Ok, first off, apologies if these questions have been answered elsewhere. Just spent the morning looking for a topic which did, but couldn't find one.

Moved into house (1930s build) in August, so this is our first winter here. Since around October time, we're noticed the windows were constantly covered in condensation on the inside and that some of the (external) walls were cold and showing mild signs of damp. This has meant that some of the draws we have backing onto external walls were found to have clothes which were infected with mildew and had to be thrown away.

We made some adjustments, such as getting a new extractor fitted to the bathroom (which is located in the centre of the house), we started opening windows, drying off excess water, keeping doors open where possible to allow circulation and installing a PIV unit, at the suggestion of a damp proofing expert who'd also put a damp course along the side of the house. We dry clothes in the house, but we do it downstairs, in the kitchen with the windows open.

Although the problems were mostly confined to the upstairs, the wall which ran under the stairs was also showing signs of damp on the inside.

However, the problems still exist, albeit to a lesser degree. The walls are still cold and show signs of moisture and the windows still get condensation. I'm stumped. We don't have trickle vents, but would that really make much of a difference?? In no other house that I've lived have I needed to go to so much effort to stop this from happening. We even (finally) unloaded some books which have been sat in boxes in the living room for a couple of months, and a couple showed signs that they been effected by damp...so what is going on?? javascript:emoticon('')

 

[JohnD]

You say you drape wet washing around the house. A load of washing can hold as much as two litres of water. If you sprayed that over the walls, would you expect your house to get damp? Buy a tumble drier.

 

[Deleted 198600]

Hi John

Like I said, the only washing we hang up is downstairs, with a window open. I don't think that is the problem. We wake up in the morning (washing or no washing, to find the same issue. I understand that we (humans) can cause condensation, but this is ridiculous. Like I said, I've never had this problems before in any other house

The gutters and downpipes are not really an issue from what I can see, and neither is the water lying on the ground. We had a water meter installed around about Sept/October time

Cheers

Matt

 

[JohnD]

when you have the taps turned off, does the water meter still move (indicating a leak)?

water vapour is lighter than air, so it moves upwards in a house.

 

[Deleted 198600]

I preempted what you were going to say about the water meter went out for two hours today and it didn't move, so I guess we don't have a leek?

Will try putting the washing in the conservatory (no space for tumble drier), see how we get on, but still not sure how this would contribute to signs of damp in bedroom. Could it be a structural problem? When I used to live at home, 5 of us in the house, never had any problem. Now two of us (different house of course), you'd think it'd be easier to control the variables, but that's not the case as everything we try doesn't get roof of the problem

 

[JohnD]

have a look under the floor. If it is wet from leaks or rain penetration, the vapour will rise up through the house. Also look in the loft for rain leaks. A leak can also be from a waste, soil or rainwater pipe, which will not show on the meter like a leak from the incoming main will.

You options are either find the sources of damp, and correct or reduce them; or increase the ventilation so that the water vapour gets out.

Cold damp air from outside contains less water than warm dry air from inside, so ventilation will always reduce damp (yes, this is true).

 

[Deleted 198600]

Thanks John, much appreciate your views on this.

We had a damp expert look at under the house before moving in as the building survey suggested. This was because they weren't sure if the air bricks were providing enough ventilation. He actually said that all things considered, it wasn't in a bad way at all, and his only recommendation was to have a damp proof course, which we have.

Could the problem be coming from the chimney perhaps? We're having a new roof put on this week (weather permitting), and part of the work involves some minor repair work to the chimney. Apparently the flashing is a bit loose and the flaunching has come away a bit. The bathroom roof does have a bulge near to where the chimney is located too

Matt

 

[JohnD]

if the house has been neglected, then with all this rain, there could be penetration especially from leaky gutters, downpipes and gullies. Walk round the house to ensure that paths and patios slope away from the house to take rain away. Yes, look at flaunching and flashing round the chimney, and any bay or porch miniroofs.

 

[AronSearle]

Assuming it is not a leak (doesn't sound like it) Ventilation will only do so much.

//www.diynot.com/forums/building/condensation-discussion.350716/

TLR cold walls, cold windows = cold surface = condensation.

Opening the windows doesn't solve that issue, it just reduces it, by reducing the air temperature and the temperature gradient between the air and surfaces, as much as removing "excess" moisture.

Your options are......

Cavity insulation will help if it is an option, and/or otherwise external insulated rendar, as well as better windows, and ensuring they are fitted with thermal breaks so that heat can't get around the frame. Essentially bring the house into the 21st century and ensure the internal surfaces are warm.

You could of course just leave loads of windows open, leaving the house nice and draughty and cold, just like they did in the olden days.

dehumidifiers, probably a few of them running 24/7 so as to excessively dry the air.

 

[Deleted 198600]

Apologies for not responding previously. I think the windows could be the issue, or maybe even defective render as both of these were highlighted as in need of TLC according to the building survey report.. We already have the cavity walls insulated see.

Have bought a few of those little boxes with crystals in that soak up moisture and they seems to be working in reducing the remaining condensation for the time being, so will stick with that until we can afford to upgrade the house.

Thanks both for the advice, much appreciated