Condensation/Damp in house?

[Bailes1992]

Looking for some advice as I know there is lots of tradesmen on here.
I'm an almost qualified electrician myself.

I have a 2 bedroom end of link/terraces house. It's a late 80's typical timber framed house. We have central heating but we don't use it much.

The roof is in good condition with no leaks.

At night all the doors are left open in the house.

We have issues with walls (especially in the bedroom) and the windows getting soaking at night. During the day we lock the windows so they are all open ajar to try and get some airflow through the house but still having issues.

There is little to no ventilation in the house which I think is a big contributor. Thus why we lock all the windows open ajar.

Our bathroom doesn't have an extractor and my missus showers with the window and the blinds shut which I'm sure exasperates the problem.

So where do I start? I have thought about buying a dehumidifier to run for a few hours every day but I think that solving the issue is a much better idea.

I think an extractor fan or two in the bathroom would work wonders but would have to fit them on a time clock and a 3 pole contactor so they don't come on at 3am.

Is it just a case of increasing airflow through the house?

Any advice welcomed.

Bailes.

[benczuk]

I assume the bedroom is small?

It is amazing how much water you exhale / sweat at night. You need to generate some air flow though the bedroom. leaving the door open is a good start but with nothing stiring the air the moisture has no where to go. We had to fit a vent in the wall of our previous house to provide some through flow to reduce the problem. A vent downstairs to allow air in would help even more. It didn't fix it entirely but combined with a repaint it made sufficient difference to stop the mold growth on the ceiling.

[trufflehunt]

Airflow, plus switch the heating on, you know you want to.

Not sure I understand your comment about the extractor fan. As I recall, there are about 3 basic types (?),
in ascending order of cost...

1. bogstandard switch on/off.
2. As 1. with adjustable timed number of minutes from switch on.
3. fans with almost silent motor.

[Welly]

Heating will raise the dewpoint temp in the house, I recommend leaving the heating on all day long; use a programmable digital room stat to regulate the temperature all day. Ours starts at 18 deg, then 19 and finally rises to 20 at 3pm. The 'fabric' of the building needs to be kept warm and then the heating will 'top up' to the required temperature as and when. This is more efficient than having the heating on once in the morning and then again at night and more comfortable too. I've been running my heating all day long for 11 years and my gas usage is quite low, certainly below average.

You need to extract from the Bathroom, you might be able to fit a ceiling-mounted fan and discharge the air to the Gable Wall (using insulated flex though) look for a Centrifugal Fan rather than an Axial as they shift more air and are quiet. Our is switched separately so we use it whilst showering and then leave it on for a while after. You can get some with run-on timers and humidistats but they can play up and be annoying.

You might be able to use a heat recovery trickle vent unit in the bedroom, extracts air but transfers the heat into the incoming air, very quiet and provides plenty of air changes in the room.

The walls shouldn't condense, this shows the surface is too cold, there might be a path for outside air to find its way into the cavity behind the plasterboard (maybe from the roof space) so worth checking.

[Bailes1992]

I've turned the heating on and fitted a thermostat on the weekend.
Had it on since 8am and things are finally drying up. I think I'm going to have to leave it on all the time.

I'm going to get an extract fan ASAP I think. I'll install it off the lighting with a timer and a timeclock & 3 pole contactor so it won't come on between lets say 9pm and 7am.
How easy is it to fit a vent in the soffits? Save me drilling another hole in the wall.

How expensive are the heat recovery systems?

[Welly]

If you can get a 100 x 100 plastic tumble drier wall vent it comes with a 100mm dia spigot on the back to accept the flexi duct, you might be able to squeeze on into the soffit and pointing down.

Not sure how much the heat recovery vents are now bit they've been around for years so should be economical enough. I'd look at this last because you'll need a fairly hefty hole through the wall for it.

[Doggy]

We have extract fans in both shower cubicles, using standard 100mm circular ducting, (I will fit the external covers one day).
12V axial fans running off combined transformer / timer unit, switches off 10 mins after the lights.

FWIW we run our gas c/h for two 30 or 40 minute 'bursts', timed for when I get up and some hours later when Mrs Doggy joins the land of the living. Afternoon / evening warmth is provided by a woodburning boiler stove.

Our cooker extractor's also piped outside - I had hoped its 150 mm circular duct would make for lower noise levels, but it doesn't

[rwb]

I've always found a dehumidifier to be essential. I always run mine over night.

[Welly]

We use a dehumadiddyfier for drying washing in a room but it does a good job of collecting warty vapour from the whole place, currently about 2.5ltrs per day.

I think there's a figure somewhere that we produce about 17ltrs of water vapour each day at home. Or something.

[gumby6371]

Not quite the same but a similar question;
My shed is a 4 metre by 3.5 metre brick building with a tin roof and suffers badly from condensation through the winter months.
I have managed to acquire some very large used pallets (4 metres long) and a roll of the thick plastic sheet FOC and was thinking of putting in a false ceiling using the salvaged timber and the plastic as a thermal/moisture barrier.

If I install the ceiling in this order;
wood then plastic with an 8" cavity where the existing joists are then the tin sheet, is that likely to cure/minimise the condensation? The tin sheet is the heavy grade almost square corrugeted stuff.

The other option is to remove the tin completely and have a wooden roof with roofing felt but that requires a dry day when I'm not at work which don't seem to come along very often.

thanks in advance and apologies to Bailes for the post hijack.

Gareth

[lozz]

if you have C/h and your radiators are located under window's. you couid add some vents there made of plastic..easy to install B&Q etc.