High Humidity in my house

[Surface Tension]

So far we're at.

Get the poly down in the crawl space.

Close off the basement windows to the crawl space.

Give that a week and check humidity in crawl space and each level of the house. Note that if be nice to have some days without rain.

Lets see what happens then and take it from there.

Get the kitchen fan vented outside.

If your stove is on an outside wall it is not hard to do.

If the stove is on an interior wall it becomes more involved and could be to the point not worth it.

[Mnfisher]

Yes, I will close off the crawl space this afternoon. I will probably leave it closed a couple of weeks then get back to everyone. Humidity in the crawl space was 56% this morning using just one of those cheap Hygrometer's, not the one with the beam from the lumber yard. That is similar to the rest of the basement and just slightly above the upstairs. Still some steam on the windows, but not on all of them. My other humidity gage says the outside humidity is 36%...kind of hard to believe given the wet conditions outside. I thought it would be higher.

My kitchen vent is on an inside wall so don't think I'll monkey with venting it outside right now but wouldn't hesitate in the future if I thought it would help.

I'll get back to everyone in 2 weeks. Thanks for your comments. Jim

[BobT]

Another thought.

Water vapor inside your home will condense on the windows if the window temperatures are below the dew point. If you are already experiencing problems I would suspect that your windows are very poor insulators and heat loss is very significant. A good quality window today should provide a better insulating quality. Triple panes, Low-E glass, and the interior filler gases that are used should provide better insulating quality allowing the interior windows to stay warmer than the dew point except on the coldest days of winter perhaps.

[muchowja]

When my brother in law built his house five years ago he did not turn on his air exchanger right away. When it got cool out he had a condensation problem on all of his windows. The water actually ran down the windows. He used quality windows (Andersen) so quality windows was not the issue. After he turned on the air exchanger the problem was gone within 24 hours. Most air exchangers are also heat exchangers so much of the heat in the air that is going out is transfered to the air that is coming in.

[Fredd]

Our house is ten years old and we have six in our family (lots of vapor from respiration). I did not put house wrap on my house because I did not want it too tight. I need to keep the heat/air exchanger running on low usually to keep my windows (Andersen's) from condensing. We also make sure to leave the shades cracked at night and will leave the furnace blower on continuous if we are having problems.

[upnorthvoice]

Another thing you can do is run a bath fan continuously for a few days to see if that improves the condensation problem. If you get less moisture on the windows a air exchanger will probably take care of your problem. Like someone said leave the blinds up from the bottom overnight a inch or two to let air movement help with the moisture. Some builders are only using bath fans that run constantly as moisture control and air exchanger as code allows it and its $2000 cheaper. You just have to be sure that it doesn't create negative pressure.

[Mnfisher]

BobT: Except for one double hung window ( I think there might be a separate problem) I don't have trouble with moisture unless the temp gets below 32. I have a couple of different types of windows in the house (not exactly sure at this point what kind but I will find out). I think the windows are ok, but not sure at this point.

upnorthvoice: I like your idea of running the fan continuously for a couple of days and see what happens, but will have to wait until the temps get below freezing again...I am pretty much "on hold" here until I see what covering up the vents from the crawl space to the basement will do. I know I need to do something though. My wife and I both suffer from allergy and sinus symptoms. I know the higher humidity is not healthy.

[upnorthvoice]

Mnfisher, I have a cabin in Itasca county with a crawl space. When I close the exterior vents in the fall, usually around mid October, I turn on a electric baseboard heater in the crawl space, this dries it out to less than 50% humidity. I have 6 mil poly on the dirt floor and nailed to the foundation with fir strips to seal the edges. Just a couple of ideas for you to try.

[BobT]

Quote:

My wife and I both suffer from allergy and sinus symptoms. I know the higher humidity is not healthy.

Hmmm. I don't know anything about those kinds of problems but for some reason I would have believed just the opposite to be true. Dry air would seem to be a bigger problem than moist air. I know I can sure breathe easier when the air is more moist....to a point I guess. Dry air dries out my sinuses something terrible. It has also been shown that increased humidity is beneficial for resisting cold and flu viruses. That's one of the reasons we're more bothered by these during winter than summer, I think.

[mn_bowhunter]

High humidity promotes mold growth, which can be circulated in the HVAC system. Mold can cause sinus infections that are pretty nasty.

[Mnfisher]

Back again! I covered the two vents from my crawl space to my basement for 2 months. I had been waiting for the outside humidity to go down which it really didn't do until the recent cold air. Covering the vents did not seem to make a difference in the humidity level in my house. I uncovered them again and still no difference so unfortunately, I don't think it is the crawl space. The humidity levels have dropped with the cold weather to approximately 45% in the basement and 32% upstairs (with a portable dehumidifier running constantly. Prior to the cold weather the humidity was running 55% in the basement and 40% on the main level, definetely too high. The windows still have moisture on them. I have all double pane windows anywhere from 18 years - 5 years old. I have combination storms on dining room, bedroom and bathroom windows. They have moisture on the inside of the storms. The other windows (without storms) have a small strip of moisture running along the bottoms of each of the panes (double hung).

Today a heating guy came over. I do not have a vent pipe bringing in outside air to my 85% efficient furnace which is 13 years old. He said we should try it (6" vent bringing in air to the cold ducts). He is not sure that will help. With moisture on the storms of most of the windows, he thinks warm air is escaping and condensing on the storms.

I'll post again after the vent has been put in and let everyone know if that helps. He wants to try that before thinking about an air exchanger. Thanks for all the previous comments. Any further comments/ideas is still appreciated. Jim

PS....On the plus side....the ice is 5-7" thick and the fish are biting! I caught 6 crappies and a nice 16" walley on rush today...midday at that!

[reddog]

Humidity wont go down outside, because it gets cold out. I looked up Glenwood Mn (random choice) and the temp is -3 and the humidity is 69%. Its not uncommon to see 75 or 85 %RH in the winter. The reason cold outside air dehumidifies a structure is because when you bring 1 cu ft of -3 degree air with 69% rh, into the house, it warms up to 68 degrees. When it warms up, it expands. The amount of h20 molecules that made 69% rh remains static. If that 1 cu ft of air expands to 3 cu ft of air at room temp, the rh is approx 23% for 3 cu ft of air. Hence the natural dehumidification in the wintertime with air leakage. It doesnt matter if the leakage is accidental (windows, doors outlets, can lights, attic bypasses, etc) or planned (fresh air intake to your furnace as suggested) The principle is the same. Cold air dehumidifies.

Moisture does not like being in a gaseous state. It wants to be solid, either in water, or ice. When it is in a gaseous state, it is constantly seeking out a condensing surface, whether thats your windows in the winter, your copper pipes in the basement, behind the insulation in your rim joist, or your cocktail glass. It wants to be in a solid state and will work 24/7/365 to find a condensing surface.

With that said. The dehumidification you wrote about today is because of infiltration. 45% in the basement and 32% upstairs still leads me to think the problem is based in the lower level. If the humidity was generated upstairs, I think you would be able to see that on the humidity levels. This time of the year, your house acts like a large chimney with the delta T (temperature differential) that is being imposed on it. You are looking at a dT of about 70 degrees, depending where you are. This dT imposes a huge amount of "stack effect" on our house. Air rises, right? If the moisture was generated on the main level, I would think that your basement would show up as the lessor of the two humidities for two reasons. The first, is that it is being generated there and typically wont migrate downward with the stack effect. The second, is that typically the lower the air leakage is in a house, the stronger the draw into the house because of stack effect, so your probably getting a pretty good amount of dehumidification from air leakage, but still carrying 45% RH

Enough of the physics for now.

What kind of ductwork do you have in the basement? Is it in the floor system?

Sump basin anywhere?

Excessive amounts of plants, or firewood stored in the house.

Moisture on the storms, is definitly air leakage from the inside getting to the condensing surface.

But, air leakage is your friend now, because with that air leakage comes dehumidification.

You said you have access to a hygrometer. Take a sheet of paper and make a column for date, time, location, RH, and temp,(both indoors and outdoors) Make a column for every room in the house, and monitor it. Make a special column for your furnace vents in each room also. You dont have to turn the furnace on, just turn the fan to on when you check each vent for RH and Temp. If the furnace is running, thats fine also.

This should allow you to eventually come up a diagnosis of where the humidity is being generated and hopefully a plan of attack for how to manage it.

[Mnfisher]

Reddog, Thanks for the helpful information. I have a regular forced air propane heating system with both hot air and cold air return piping....typical metal piping. 3 bedroom 1300 sq ft...with an additonal 300 sq foot 3 season porch that is open to the kitchen/dining all year long. Sump pump in basement...with a wooden cover. Washer/dryer in basement vented to the outside. We got rid of most plants a year ago, only two of us now and we have a bathroom exhaust fan installed a year ago. I will "borrow" that digital hygrometer again and take some readings like you suggested within the next few days (in between ice fishing) and get back to you. If the humidity is generating from the basement, a cold air intake to the cold air vents should help shouldn't it? Could my windows be defective? They are double pane well known brand name windows. Porch: 1991, (no storms); dining room, bedrooms, bath: approx 1999 (new combinations 2 years ago; living room: larger double hung, and stationary center window with double hung on each side..no combinations. WE have the one dehumidifier running year round, basement in summer and upstairs during winter. Seems to help some. Thanks again...Jim

[Fisherman For a Lifetime]

reddog, you rock - my Fiance has the same problem in her house thet we'll sell in the Spring...

My house is very similar also.

Will be watching this thread closely, thanks.

[reddog]

Im out in South Dakota hunting, so I dont have alot of time, but....

Cold air intake to the return air, in my opinion would be a bandaid. Would it decrease the humidity? Sure it will. Will it cost you more in energy consumnption, yes.

You windows are probably not defective. Your house generates too much humidity, is the problem.

Finding the problem, can be a troublesome task.

Is there any exposed concrete in the basement? Another thing youy can do to get some diagnosis is to take a patch of plastic and tape it to the floor(all 4 edges) and find out how much hunidity is coming thru the concrete.

[acman2u]

Mnfisher,

Just to understand, did the hvac guy reccomend a cold air or combustion air? New code requires a combustion air supply to provide adequate air for proper combustion, older houses did not need them as they "leaked" air, now with the tightness of the houses we need combustion air to the mechanical room. I would also lean towards an air to air but something does not seem right in your situation, your level of RH is just too high. Did the service person check to see if both your furnace and water heater were drafting correctly? Quick check for water heater is to light a match, blow it out, and quick hold it at the vent for the water heater to see if the smoke goes up or into the house. when furnace is running can you feel hot air near top front of the furnace in front of the draft diverter. The level of humidity really points me to your equipment.

I hope this helps, please post back as you get more info.

[Mnfisher]

Reddog; I have painted all of my blocks and floor with a waterproofing paint. There does not seem to be any moisture coming in. I'll try the plastic to the floor trick. I used to have a lot of moisture come into the basement before I put up gutters and did a little landscaping with rocks around troublesome areas and have had no visible moisture since. I recently removed some sheetrock from two walls in one room in the basement. There was mold on the inside of the sheetrock but I think it was pretty much contained, if that is possible. That was in the room that I had water come in several years ago. We are situated on a hill but with lots of swamp land surrounding us. Soil is a lot of clay. The local lumberyard owner said I could dig down around the house about two feet, spread plastic, then some rock? and try that rather than dig all the way to the footings, but that is a lot of work too. I'll keep you informed and thanks again so much for the advice.

[Mnfisher]

acman2u: I didn't see your post until I responded to Reddog. I think the heating guy recommended cold air, but I will ask him. Maybe because our home is older, codes would be different and we wouldn't need the combustion air. I'll ask him to check the hot water heater and furnace when he comes back. Thanks

[Mnfisher]

Update on my humidity problem: The heating guy installed a 6" cold air intake directly to my cold air duct. That seemed to help the windows that were showing moisture strips on the inside but has not completely taken the moisture away. I could open up the damper a little more, but the furnace is already running more and I can just see those $$$ going up the chmimney. It is better though.

The windows with combination storms on them are the same. Much fogging/moisture on the inside of the combinations. Heating guy can't figure out why. It seems that warm air is escaping through the double pane, double hung windows that were installed about 6 years ago. I wonder what a Low E type of combination would do? I suppose it would prevent cold air from coming in, but it would seem that the same problem of moisture escaping from the inside would still be a problem. Any comments?

Would knew Low E triple insulated windows be helpful? They are not cheap but I would consider them if I thought it would take care of the problem.

The "Psychrometer" I was using to measure the humidity had a low battery (didn't find out until the day I had to return it) so don't know how accurate the humidity readings were. They seemed to vary from 30 % to 45 % both up and in the basement, not extremely high, according to the heating guy. You don't want it too dry in the winter I guess. I will try the "Psychrometer" again in a couple of weeks with good batteries!

Happy Holidays to everyone!

[MNice]

The heating guy installed a 6" cold air intake directly to my cold air duct.

Check with the furnace manufacturer. Newer furnaces will not let you do this, because the heat exchanger is not designed for the cold shock of all that out door air. Check the manual, many will have a statement to limit the temp. of return air to around 55-60 degrees.

[Mnfisher]

I don't have an air exchanger. The furnace is 13 years old and 85% efficient, I believe.