High Humidity in my house

[Mnfisher]

Hello! I have been having problems with high humidity for a few years. I use a de-humidifier all winter but still does not solve the problem. Lots of moisture on windows, when the temp gets below freezing, especially in 4 season porch addition with crawl space. There is a poly moisture barrier on the additon dirt floor (block walls with styrofoam also). Moisture seems to be starting in the basement. Plastic helps on the inside of the widows. Humidity running 59% in basement and 53% up stairs. Have installed bathroom fan, more installation in attic new windows, painted basement walls and floor Any ideas? I know many things can be happening. Does anyone know an expert in this kind of thing in East Central Minnesota that I could get a professional evaluation from? Thanks for any help. Jim

(I will be gone thru Tuesday so won't be able to respond or answer any questions).

[Tom7227]

Could you have a leak in the exhaust of the furnace, water heater or dryer? Something this persistent has to be coming from a fresh source of moisture. Try putting a CO2 detector down theree and see if it lights up. Then inspect the vent lines of all the stuff down there and see if you find any leaks. Other thing could be a bad draft on someething that allows the exhaust to back up in the basement.

[BobT]

Sounds like your home is newer and very air tight. It's not uncommon to have to put in an air exchanger in this situation. One small dehumidifier may not be enough to keep up. My brother-in-law had to do that to protect his Anderson wood frame windows from rotting.

[norm25]

For me if I don't run my air to air exchanger in the winter my windows would be completely iced up on below zero days. Problem is I installed the exchanger and almost all the windows in my residence are rotted out on the interior. I have electric radiant heat. You did not specify the age of your home or heating source or what type of system of heating you utilize, that will aid in answering your question.

[Mnfisher]

Thanks for the replies so far. I have a Co2 detector upstairs in our bedroom and it has remained at 0. I will try moving it downstairs to see what the reading is. The house is 35 years old with no moisture barrier on the inside of the exterior walls. When we had steel siding installed 18 years ago, they put a barrier on the outside. We have forced air propane heat. Water heater is propane also. I have considered an air exchanger. The furnace is 13 years old. Even though the house is older, I consider it pretty air tight, but maybe not. 2x4 wall construction. Good windows, good insulattion in the ceiling. Thanks, Jim

[BobT]

I don't know much about LP heating systems or water heaters so this may be a silly question but are your furnace and water heater vented outdoors or inside? If inside, I'd suggest venting them outside. The exhaust from LP will contain high amounts of H2O.

Also, I assume your clothes dryer (if you have one) is vented outside.

[BobT]

Quote:

For me if I don't run my air to air exchanger in the winter my windows would be completely iced up on below zero days.

Maybe I'm wrong but that sounds backwards to me unless your exchanger also has a humidifier. The way I've understood is that the colder the air becomes outside, the less water vapor it can hold per cubic unit. That's my understanding of how an air exchanger works. When a house is too air tight, the air inside can become too humid. An air exchanger brings in dryer outside air and exchanges it with humid interior air.

My understanding is that when you warm cold air up, the relative humidity will drop because as the air gets warmer its capacity to hold moisture goes up. The dew point of outside air in mid-winter is very low so when you bring it indoors, there's less moisture to condense on the windows.

[Surface Tension]

If you have a lot of moister on the windows with humidity levels at 53% your windows are no good. An old single pane with a storm window is enough of a thermal brake to not have any condensing. Depending on how leaky that window is, you might see a little condensation on the storm but not on the interior glass.

To the original post.

Look for ways to reduce the humidity your putting into the air.

Most obvious is the shower and bath. The exhaust fan in the bathroom should help but if your turning it off right after a shower you still going to have a large amount of moister left in the bath room. Run the exhaust fan longer.

Kitchen, an exhaust fan vented outside there while cooking is going to help a lot. Use covers when boiling water.

Just remember, when that fan is pushing indoor air outside, outdoor air has to be coming from somewhere. If a house is tight, back draft from the furnace or water heater is a concern.

So we know the humidity in the basement is 59% and humidity upstairs is 53% now tell us the temps upstairs and downstairs.

During summer are you using an air conditioner? The cooler the air the less moister it can hold. Also as the warm humid air inside passes through the air conditioner it condenses and is expelled outside. Your dehumidifier is taking water out of the air but it is putting heat into your room. So use the air conditioner in the summer. If you can't get the humidity down in the winter then use the dehumidifier.

If it ends you house is tight then you'll look at an air exchanger just to get the stale/unhealthy air out. You'll still need to reduce the obvious high sources of humidity.

How do you find that out. A home analysis is the only way to know for sure.

[Mnfisher]

The furnace is vented to the outside. Not sure about the LP hot water heater. Dryer is electric and vented outside. Windows in main house are newer and I have installed new combinations almost 2 years ago. Porch windows,(addition was built in 1991)always have had moisture on inside of windows that drips and causing middle sils? to turn black. Have sanded and revarnished a couple of times. A couple of local people have not seemed to be too motivated to help solve my problem. Who in the area can do a complete Home analysis?

Thank you. I really appreciate the good comments. (Will be gone now until Tuesday PM)

[archerystud]

I had the exact same problem.

We had an analysis done by the gas company and they told me they had good news and bad news. The good news was that I had the spent the least of anyone in my neighborhood on natural gas. The bad news was that I had spent the least of anyone in my neighborhood on natural gas.

Our house was built in 85 but we have resided and put in new windows and now my house is sealed up pretty tight. The problem is that this can eventually lead to a mold build up in the walls and then you will have big problems from what I was told.

I saved up for a year and put in an air exchanger and we really don't have any problem with water build up on the windows.

The analysis was done by the gas company (I believe) and it was free.

[Jim916]

We had a problem with moisture on our windows too. We had bad windows to begin with and 5 windows ended up cracking from the ice build up. The windows lasted 10 years in a new house. The window company had also gone out of business in that time. We put new windows in and a year later we put an air exchanger in and it pretty much solved the moisture problem.

Like they say if you have moisture on the windows, you most likely will have moisture in places you can't see.

[Chad711]

If you do not have an air exchanger, you need one. common problem, and a properly installed HRV will do the trick. Be prepared to pay near $2000 for one though, they are expensive systems.

[mn_bowhunter]

It doesn't matter what you've got for windows if the humidity is 53% inside in the winter - you will get condensation. Like others have said, try to address the sources of moisture. How many showers per day in the house? Are most meals made on the stove? Think of all the places moisture could come from and try to eliminate them. I'd also add another dehumidifier in the meantime to keep from destroying the windows.

[Mnfisher]

I appreciate the replies. I will talk to my propane guy to see if he knows someone who can give me an analysis. On October 9, I borrowed a digital humidity/temp instrument.

Outside: 47 and sunny. Humidity: 29%

Upstairs: Temp: 70 - 72 and Humidity 49% - 50%

Wall temps: 58 (3 season porch) - 68 degrees, ceiling temps: 61 (porch) - 68 degrees

Basement: temps = 66; walls 52 - 55, Humidity: 52 - 56%

The local lumberyard owner told me I need poly on the dirt floor of my porch addition and that it should be glued to the block walls. The block walls are insulated with styrofoam, but the poly is NOT glued to the walls. Would that make such a big difference?

[Surface Tension]

You said you've had this problem for a few years. What has changed, the addition with the crawl space? Its sounds like the crawl space isn't vented either. Yes you can be getting moister from there and it can go right through poly. What mil is down there now and is it at least weighted down around the perimeter?

[Mnfisher]

The addition was put on in 1991. We had a Fisher wood stove in the adjoining dining room/kitchen for a number of years which really kept the areas dried out but stopped using it about 10 years ago. The last two years, I've used poly on the porch windows, which helped. Poly on the outside did not help, but only helped on the inside which leads me to believe the problem is the humidity on the inside. Two years ago I put on new combination storms on the windows that were not two paned. I am not sure what thickness the poly is over the dirt floor in the addition and it is vented via two openings into the basement (where two small windows were before the addition. It is not weighed down in the corners but it looks fairly thick. Porch in 1991 with thermal windows, new windows, single pane with combinations in dining room, bedroom, bath in 1998? new thermal wndows in living room 2002? and new combinations on single pane windows 2007. So many changes it's hard to figure exactly when the foggy windows really started or started to get worse, but I'm thinking things went downhill after the addition in 1991.

[Surface Tension]

So you crawl space is not vented to the outside, rather it is opened up to your basement. I think I remember an earlier post of yours about that. Close that off for a week then measure the humidity in the house and then in the crawl space. It would be best to vent that crawl space to the outside during summer. I'll bet its damp under that poly too. Get the poly down so it is not letting moister out.

Right now we are in a limbo stage. Not that much heating going on, no air conditioning going on. Not to mention rain and %100 humidity. As the cooler temps come so will dryer air. Keep that crawl space closed off and see what happens.

Also run that bathroom vent and the kitchen needs a vent if it doesn't have one. If you need the air exchanger then so be it but don't get roped into one if you don't need it. Not only will it cost for install but your heating bill will go up as well.

[Mnfisher]

Thanks Surface Tension;

I will make sure my poly is sealed down and then close off the two screened areas to my basement. Today with the temp at 43, there is no moisture on my windows as usual. Two more questions: Wouldn't it help in the winter also to have that crawl space vented to the outside? My kitchen fan is vented internally, not to the outside. Will that make a difference?

I appreciate your help. I enjoy the Fishing Minnesota site very much. Good luck fishing!

[BobT]

If you have a crawl space under a porch or something, then yes, you'll want to install ventilation.

The kitchen fan being vented inside means that all it is doing is blowing the steam and excess heat from your cook stove around the room. Its only purpose is to improve the comfort of the cook. To get rid of the excess steam, you'll need to get it out of the house.

[Mnfisher]

If I install ventilation in the crawl space to the outside, should I block the current ventilation to the basement? Wouldn't ventilation to the outside allow a lot of cool air to come into the crawlspace making the porch a lot cooler too?

[WallEYES]

Depending on how big the crawl space add a couple of supplies(heat runs) and keep your forced air furnace fan running at all times to keep air curculating at all times. DO NOT add vents to the exterior to the crawl space....They do this down south and not made for northern climates. Another idea would be to get a 100cfm bath fan rated for continuous operation and wire it to an humidistat to rid of any moisure, also seal the poly.

[BobT]

I have to respectfully disagree.

Trailer house skirting is vented to control moisture. Likewise, all the literature I've read reagarding closing in under a porch, deck, or crawl space have always recommended insulating the floor above the area very well and venting to the outside.

What I read also recommended putting down a moisture barrier (heavy plastic for example) on the ground in the crawl space and covering it with clean sand. If you don't vent it somehow, you encourage molds, rot, and insect infestation.

If you are venting through the basement, I can see that you would not want ot vent outside, though.

[Mnfisher]

Yes, I am venting through the basement but wonder if venting outside would rid the area of moisture, sending it outside rather than into the basement and then into the rest of the house. BobT, I like your idea of venting to the outside as I know that trailer houses are vented this way. Insulating the ceiling (porch floor) of the crawls space makes sense to keep the colder air from penetrating the floor.

I like WallEYES idea of puting in a bathroom fan on continuous run, or maybe a high/low/off fan with switch upstairs in the porch. You would vent that directly outside wouldn't you?

[BobT]

I wonder what the cost would be to leave a fan running continuously in a bathroom. Not so much in terms of electrical use but heat loss.

Suppose you have a 2000 sq.ft. home with 8 foot ceilings and you run a bathroom exhaust fan at 50CFM continuously.

2000 * 8 = 16,000 cu.ft.

16,000 / 50 = 320 minutes

320 / 60 = 5.33 hours

24 / 5.33 = 4.5

You'd be exhausting the entire volume of air in your home about 4.5 times every day. Imagine what that might do to your heat bill. Might as well just open a couple windows maybe.

I suspect the negative atmosphere you'd create wouldn't be real pleasant either. Every nook and cranny would be leaking air into the home creating a very significant drafty feeling.

[Tom7227]

Bob's right about the continuous fan. Overkill. How about getting a timer for the bathroom fan like the one you see on the heat lamps? Only issue then would be to 'train' the folks in the house to use it.

But back to something in the first parts of the post. Right now my house has 53% humidity and I don't think that's a sign of anything other than that it is very humid outside right now. It's not cold enough to drive down the outside humidity and the furnace doesn't run that often to have dried out the house like in the winter. I'm not so sure this man's humidity levels are that far out of whack for the current weather conditions.