Moisture in house

Further to my thread of a month or so ago about insulation, heat transfer systems, fighting condensation, some friends gave us the loan of a dehumidifier. We've been running it in various areas of the house for about a little over a week:

The bathroom/back bedroom area put out about 4L in about 12 hours. This area is roughly 14 sq m

Our MBedroom, with all the condensation probs and black mould from last year put out about 2L over 12 hours. This room is roughly 20 sq m

The main living area, which is lounge/kitchen (about 50 sq m), put out 8L in 12 hours!!!

I'd expected more from the bathroom area, as it's in a cooler part of the house, and that's where everyone (4 people) showers.

I know the dishwasher can fog up the windows, especially when it's cold out, fairly quickly. We do have an extractor fan over the stove, and that has helped very noticeably, at keeping cooking moisture out of the house, and vented to the outdoors. I can boil a pot of potatoes or pasta without fogging up the whole room now.

So, given that it's been a cool and damp summer, I had also expected more moisture than a NW summer, but I am really astounded at just how much moisture is in the air in our house!

I'm going to run the dehumidifier again for a day when we next have a NW wind blowing, and see what I get.

Still, we need to find a way to not live with so much moisture in the house (or is this just normal??!), as it does affect my sinuses and lungs and my DH has had flare ups of his asthma, which hasn't bothered him in years. (Could also be the dust of Chch, as I know I really get plugged up when I have to go into town....)

Andrea, Don't forget the body give off several Litres per day, Insulation and air changes are the most important. The higher humidity in the house the harder it is to heat.

Also watch your power bill rise with humidifier on for several hours per day.

Yeah, we figured that it was going to cost about $4-6/day to run the thing for 24 hours, if we chose to do so. What are the options? Chronic health problems? Forgot about the body giving off fluids, but would it be several liters a day in just perspiration??

Andrea;410113 wrote: Yeah, we figured that it was going to cost about $4-6/day to run the thing for 24 hours, if we chose to do so. What are the options? Chronic health problems? Forgot about the body giving off fluids, but would it be several liters a day in just perspiration??

Respiration (breathing) and perspiration is generally regarded as being responsible for 1 - 1.5 litres of moistre per person per day.

I have a dehumidfier that I no longer use. When I first moved to Waikato (from Canterbury) I was amazed at the humidity - summer and winter. Then I was living in a small, brick house. Now I am living in a bigger wooden house and have far less of a problem. Even running the dehumidifier all day I barely got more than a cup of water.

I notice that having a woodburner really dries the house out in winter.

Andrea, what is you home built of. The older wooden homes have better breathability compared with modern homes where everything is sealed. Location of the house can affect moisture levels, eg is it sited over underground water courses. There a whole bevvy of issues but if you are growing mould on walls then either you need to ventilate better, use the dehumidifier, look at whether you need to insulate your underfloor etc. eg if you are located over damp ground then there are many litres a day rising up into your house and plastic sheeting on the ground can do a lot to elimate that.
I would be getting an expert in to look at the situation, we dont really have all the facts to help you without seeing your conditions
If its affecting your health then obviously something needs to be done

A couple of observations here:
1. unless your house is hermetically sealed you will not be able to reduce inside humidity below the level of outside humidity - NZ has a very humid climate so you will always be able to extract plenty of water from it - the cheapest way to ensure that your inside humidity is not higher than outside is to open a window
2. Warm air can hold more moisture than cold air - hence you getting less water from the bathroom in a cold part of the house than from the warmer living room
3. generally speaking condensation is the actual problem that causes mold etc - condensation happens on surfaces that are colder than the surrounding air - e.g. windows, outside walls and the business end of a dehumidifier - this can be helped through double glassing windows either with real glass or with much cheaper 3M window film and by insulating the walls

It's an old wooden house - wooden frame, wooden weatherboard siding. No underground water, except maybe more than 300m deep. The underside of the house, that we've been able to see anyway, is pretty dry. There was a wet corner when we first moved in 8 years ago, but that was a downpipe going nowhere but flowing under the house, and that's been long since fixed.

What type of expert would one use to help 'diagnose' this kind of problem?

By better breathability, are you meaning that this is a boon or a curse?

We've put double glazing in most of the house. Couldn't afford the two big front windows, so have left those till we can. Supposed to be getting a quote on them next week, as a matter of fact! If that's too dear, then will go with the window film. The double glazing has made a huge difference where it's been put in so far. We intend to do traditional batts at some stage when the budget allows, but it would mean re-siding the whole house in order to do it properly with a damp-proof membrane...

We'll get a handle on it, just will take time.

Thanks for all the replies.... very good points to consider.

it's been a very humid summer.. perhaps it's just that..

I did the air foam insulation (goes in through little holes) for my house and found it very worth while and much less hassle than re-siding the walls.

Andrea, its better that houses breathe rather than being hermitically sealed.
I also live in an old turn of the century cottage and last year i got underfloor insulation and ceiling insulation. I used to get condensation on the windows but not any more. The whole house felt different, i could feel the effects immediately.
Look up the building institute on the net and home insulation as well, there are govt subsidies for that. I know in auckland we have a building advisory centre and its possible other areas have the same where you can ask these kind of questions

We put an HRV system into a small 1960s weatherboard bungalow once. Had no insulation anywhere when purchased and no double glazing. Was heated with a woodburner.

We had weaping windows in winter. Got the blow-in insufluff (sp?) into the ceiling and the HRV system - and no more weaping windows. The HRV takes warm air from the ceiling and transfers to the house - it made a real difference to maintaining a slightly higher temp as well.

Wasn't cheap but it did what they said it would - so we were happy.

do you find the house is drier in winter with fires going?

We were thinking more along the lines of a simple heat transfer system, just taking the excess warm air from the lounge/kitchen, where the Osburn 2400 lives (and is really overkill for this little house, but it was here when we moved in), and ducting it to the bedrooms. DS's bedroom, directly across from lounge, hardly ever gets damp in winter, however the two bedrooms on either side do. It's not major, compared to a lot of what I've seen in others' homes, but then again I'm home most of the time, so the fire is going 24/7 in winter. The woodstove is the only source of heat, and the house is usually quite comfortable in winter, unless we get a long stretch of near freezing temps. Then the bedrooms do take longer to warm up in the mornings, and there is more condensation on the windows.

In thinking back to last winter, due to a new cat who was terrible for peeing in our bedroom, we kept the door shut most of the time. That could very well be why all the mould behind the dresser and bookshelf. We've since figured out that cat is ultra-fastidious, and if his litter box is kept clean, he uses it rather than elsewhere in the house.

I know people say to leave windows open in winter, at least for a wee while, but except for the bathroom, I can't bring myself to do this, as we get quite cold here in winter, and it sets up nasty draughts all over the house.

Kind of a vicious cycle we've got going...