Who can solve my home's moisture problem?
November 3, 2013 2:51 PM Subscribe
I have an unusual house, a winterized cabin that's fairly tightly sealed but with a crawl space beneath and no attic (cathedral ceilings). The whole space is heated with one propane stove, the kind with the fake logs and real flames, which is quite nice; a large ceiling fan on the second floor helps move the air around. I have had moisture problems -- condensation on all windows in the winter, mildew growing on certain furniture, books, shoes, etc. for the entire time I've lived here, but it seems like it's been getting slowly worse. Given my unusual HVAC set-up, what kind of specialist should I call to diagnose the problem? I know I could just buy a dehumidifier but I'd rather get to the heart of the problem.
You can install a crawl space moisture barrier yourself, but you also need ventilation for your tightly sealed house. Here we do it with vents; where you are it's more typical to do it with mechanical ventilation. See here and here. The ventilation is critical; the damp air needs somewhere to go.
posted by DarlingBri at 3:08 PM on November 3, 2013
posted by DarlingBri at 3:08 PM on November 3, 2013
Combustion creates moisture. Are you sure the stove is venting properly?
Also consider a waste heat recovery device for warming up the incoming air when you add the incoming ventilation.
posted by flimflam at 3:17 PM on November 3, 2013 [1 favorite]
Also consider a waste heat recovery device for warming up the incoming air when you add the incoming ventilation.
posted by flimflam at 3:17 PM on November 3, 2013 [1 favorite]
Best answer: 1) First, reduce the input of moisture into the conditioned space.
Moisture barrier between the ground (damp) and crawl space. This is top priority and anyone reasonably competent can do this for you. Use heavy gauge plastic and seal to the crawl space walls. This will likely make a very big difference.
Is the propane stove vented to the outside?
If you don't have good bathroom and kitchen vent fans, install them - much of the moisture in your house comes from cooking and showering. HVAC person.
Otherwise, the big sources of moisture are people, pets, and plants.
2) Ventilate
Either plain mechanical ventilation or a heat recovery ventilator (so you don't lose all the energy in your heated air). A competent HVAC person is a good idea for this, but such a person can be difficult to find.
If you don't want to take these steps on your own without an assessment from someone, I would look first for a competent energy auditor. They tend to understand moisture and ventilation issues and they can test your house for airtightness as well, which may factor in to your ventilation solution.
posted by ssg at 3:20 PM on November 3, 2013 [4 favorites]
Moisture barrier between the ground (damp) and crawl space. This is top priority and anyone reasonably competent can do this for you. Use heavy gauge plastic and seal to the crawl space walls. This will likely make a very big difference.
Is the propane stove vented to the outside?
If you don't have good bathroom and kitchen vent fans, install them - much of the moisture in your house comes from cooking and showering. HVAC person.
Otherwise, the big sources of moisture are people, pets, and plants.
2) Ventilate
Either plain mechanical ventilation or a heat recovery ventilator (so you don't lose all the energy in your heated air). A competent HVAC person is a good idea for this, but such a person can be difficult to find.
If you don't want to take these steps on your own without an assessment from someone, I would look first for a competent energy auditor. They tend to understand moisture and ventilation issues and they can test your house for airtightness as well, which may factor in to your ventilation solution.
posted by ssg at 3:20 PM on November 3, 2013 [4 favorites]
Sounds like an unvented propane heater to me. The same thing happens when people use those portable propane heaters indoors -- they put out huge amounts of water as a combustion byproduct.
posted by Dip Flash at 3:48 PM on November 3, 2013 [1 favorite]
posted by Dip Flash at 3:48 PM on November 3, 2013 [1 favorite]
Best answer: Hey chowflap! You might want to check out an energy consultant from Mass Save. They can come in and do an energy audit for you. I've lived in places with the mold on the shoes and books, and it's NO FUN AT ALL!
I would start with them, and if they don't help, I would ask around to my neighbors at the local corner store and see who they recommend for HVAC and similar problems, because if you have them, chances are your neighbors have them too. Just be glad you don't have snakes in your bedroom like I used to!
posted by Marie Mon Dieu at 5:16 PM on November 3, 2013
I would start with them, and if they don't help, I would ask around to my neighbors at the local corner store and see who they recommend for HVAC and similar problems, because if you have them, chances are your neighbors have them too. Just be glad you don't have snakes in your bedroom like I used to!
posted by Marie Mon Dieu at 5:16 PM on November 3, 2013
Seconding Dip Flash and others. If your propane stove isn't vented outside it's most likely the source of your moisture problems. In a tightly sealed space un-vented gas appliances can also produce dangerous levels of carbon monoxide.
posted by islander at 5:35 PM on November 3, 2013
posted by islander at 5:35 PM on November 3, 2013
Your need new or better insulated windows. The warm moist interior air encounters the cold glass surface of your windows and condensation occurs [like a cold bottle of beer on a hot summer day] which then evaporates with the heat. You have an engine to generate humidity. Living spaces need to be evenly insulated.
On the cheap and ugly you can buy window shrink film but what you really need are better insulated windows.
posted by vapidave at 5:43 PM on November 3, 2013
On the cheap and ugly you can buy window shrink film but what you really need are better insulated windows.
posted by vapidave at 5:43 PM on November 3, 2013
To be specific, propane is C3H8. When combined with oxygen (5 O2) it breaks down into 3 CO2, 4 H2O, and heat. You don't generally notice the H2O thanks to the heat, which turns it into steam. That's the steam that's condensing all over your house.
posted by waldo at 7:31 PM on November 3, 2013 [1 favorite]
posted by waldo at 7:31 PM on November 3, 2013 [1 favorite]
Response by poster: My propane stove is vented outside. It has a stovepipe similar to a woodstove's except it only goes up a few feet and then takes a right angle to the outside. Could it still be producing steam into the living area? I have bathroom fans (the one in the full bath is on a timer and stays on for 90 minutes) and a range hood, though they don't seem to have much draw. And I believe I have a moisture barrier, but it might be somewhat compromised at this point.
posted by chowflap at 7:56 PM on November 3, 2013
posted by chowflap at 7:56 PM on November 3, 2013
I came here to say it's the heater, but you say it is vented (flued?) to the outside? I would double-check that, and that no combustion gas is entering the house. If you need gas heating, you need a flued heater.
Having replaced an unvented LPG/propane heater with a flued one, I can happily state that the reduction in steamed windows/mildewed ceilings is remarkable.
If that is not the source of your moisture, then I am out of experience/knowledge to assist, sorry.
posted by GeeEmm at 8:45 PM on November 3, 2013
Having replaced an unvented LPG/propane heater with a flued one, I can happily state that the reduction in steamed windows/mildewed ceilings is remarkable.
If that is not the source of your moisture, then I am out of experience/knowledge to assist, sorry.
posted by GeeEmm at 8:45 PM on November 3, 2013
I don't know if this will solve your problems (it doesn't address the source), but renters with moisture problems in Switzerland (the buildings here are often very well sealed) are strongly suggested to ventilate their apartment 2 times a day by opening all (or many windows) for 10 to 15 minutes.
It is a bit sad to see all that warm air leave your building, but you might want to try it for one winter to see if it brings any improvement. It is stated/believed here that 2x 10 to 15 minutes is much more energy efficient than leaving windows open all day.
BTW, I find the fresh cold air in the morning super refreshing. I also love to look outside my open bedroom window first thing in the morning to get a feel for that day's weather (snowy, rainy, sunny - whatever).
Good luck!
posted by jazh at 1:27 AM on November 4, 2013
It is a bit sad to see all that warm air leave your building, but you might want to try it for one winter to see if it brings any improvement. It is stated/believed here that 2x 10 to 15 minutes is much more energy efficient than leaving windows open all day.
BTW, I find the fresh cold air in the morning super refreshing. I also love to look outside my open bedroom window first thing in the morning to get a feel for that day's weather (snowy, rainy, sunny - whatever).
Good luck!
posted by jazh at 1:27 AM on November 4, 2013
fairly tightly sealed
Is not healthy. Every enclosed living space should have some ventilation. In my flat in Sweden I have the old-fashioned double-paned windows, but there are holes drilled around the frame to let fresh air in. You can close these when it's really bitter cold outside, but otherwise a bit of fresh air circulation is vital.
When I lived in London in an old flat with double-sash, single-pane windows in front of which you could feel a breeze, it seemed insane. When I asked the landlord why, he remarked that the climate was damp in London and without that ventilation mold would be all over the walls. "Put up some heavy curtains, but don't try to seal the windows."
So "tightly sealed" is the wrong answer. Even if you put in a decent flue, you still have to have holes to the outside somewhere so that fresh air can be drawn in. Open one of your windows a crack and that will make all the difference.
posted by three blind mice at 7:19 AM on November 4, 2013 [1 favorite]
Is not healthy. Every enclosed living space should have some ventilation. In my flat in Sweden I have the old-fashioned double-paned windows, but there are holes drilled around the frame to let fresh air in. You can close these when it's really bitter cold outside, but otherwise a bit of fresh air circulation is vital.
When I lived in London in an old flat with double-sash, single-pane windows in front of which you could feel a breeze, it seemed insane. When I asked the landlord why, he remarked that the climate was damp in London and without that ventilation mold would be all over the walls. "Put up some heavy curtains, but don't try to seal the windows."
So "tightly sealed" is the wrong answer. Even if you put in a decent flue, you still have to have holes to the outside somewhere so that fresh air can be drawn in. Open one of your windows a crack and that will make all the difference.
posted by three blind mice at 7:19 AM on November 4, 2013 [1 favorite]
If you live in MA and the house gets moist enough in the winter to grow mildew, I would have to think there is some kind of water intrusion going on. Leaky roof or pinhole leak in a water line, or a crawlspace that is literally swampy.
posted by gjc at 8:08 AM on November 4, 2013
posted by gjc at 8:08 AM on November 4, 2013
Is your bathroom/shower properly vented?
Do you use an aerating shower head to reduce water usage? Those can put a lot of water into the air. (There are other low-flow shower heads that are not aerating.)
posted by alms at 10:40 AM on November 4, 2013
Do you use an aerating shower head to reduce water usage? Those can put a lot of water into the air. (There are other low-flow shower heads that are not aerating.)
posted by alms at 10:40 AM on November 4, 2013
Response by poster: I do live in MA, but my house is essentially in a forest, and the land is very sandy (so I've been told). Showerhead is not aerated. Again, the propane heater is vented; I have carbon monoxide detectors on each floor, and they've never gone off. I think the home is too tightly sealed, so I'm concerned about getting a "seal your home's envelope!" person here.
I do appreciate all of the answers! I really wanted to find out what sort of tradesperson would be the right one to come look at the problem and suggest solutions. Anyone know?
posted by chowflap at 12:54 PM on November 4, 2013
I do appreciate all of the answers! I really wanted to find out what sort of tradesperson would be the right one to come look at the problem and suggest solutions. Anyone know?
posted by chowflap at 12:54 PM on November 4, 2013
Response by poster: Actually, now I see ssg gave me the answers I needed. I might as well start with the (free) Mass Save folks. Thanks, best answerers.
posted by chowflap at 12:56 PM on November 4, 2013
posted by chowflap at 12:56 PM on November 4, 2013
Good choice! Don't worry, any competent "seal your home's envelope!" person is actually a "seal your home's envelope AND ventilate for proper air quality (including moisture control)!" person.
By the way, there is no such thing as too tightly sealed, despite what many will tell you. As tightly sealed as possible, plus mechanical ventilation (preferably with heat or energy recovery) is much better than hopefully somewhere around the right amount of ventilation (but in reality too much or too little depending on changing variables). You will never get a leaky house with a reasonable natural ventilation rate on both a calm late fall day and a blustery night in the dead of winter.
Green builders build houses that are sealed much tighter than any winterized cabin ever will be and then install mechanic heat recovery ventilation for great air quality. This is a good problem to have!
Good luck, let us know how it works out.
posted by ssg at 1:19 PM on November 4, 2013
By the way, there is no such thing as too tightly sealed, despite what many will tell you. As tightly sealed as possible, plus mechanical ventilation (preferably with heat or energy recovery) is much better than hopefully somewhere around the right amount of ventilation (but in reality too much or too little depending on changing variables). You will never get a leaky house with a reasonable natural ventilation rate on both a calm late fall day and a blustery night in the dead of winter.
Green builders build houses that are sealed much tighter than any winterized cabin ever will be and then install mechanic heat recovery ventilation for great air quality. This is a good problem to have!
Good luck, let us know how it works out.
posted by ssg at 1:19 PM on November 4, 2013
I really wanted to find out what sort of tradesperson would be the right one to come look at the problem and suggest solutions.
We went through half a dozen trades people trying to figure out our bathroom moisture problem. A couple of contractors, a mold specialist, an HVAC person, and a plumber or two. We got a bunch of suggestions that we implemented, but none of them fixed the problem. I finally got the idea on my own to replace the shower head, we did that a couple of days ago, and it seems to be working.
The moral: a trades person may or may not be able to figure this out for you.
posted by alms at 1:58 PM on November 4, 2013
We went through half a dozen trades people trying to figure out our bathroom moisture problem. A couple of contractors, a mold specialist, an HVAC person, and a plumber or two. We got a bunch of suggestions that we implemented, but none of them fixed the problem. I finally got the idea on my own to replace the shower head, we did that a couple of days ago, and it seems to be working.
The moral: a trades person may or may not be able to figure this out for you.
posted by alms at 1:58 PM on November 4, 2013
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posted by Exchequer at 2:55 PM on November 3, 2013