# Indoor humidity



## gma2rjc (Nov 21, 2008)

I don't know if this helps, but here are a couple pictures of the controller and humidifier.



















Barb


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## gotogregg (Sep 16, 2010)

Hey Barb,
This is a very interesting problem. I am very curious to what could be causing this. Your whole house humidifier is off and the damper is closed so it can’t be causing the humidity. It is also cold outside so you are running your heat, right? 
Is there water collecting on all the windows like in the picture of the patio door?
How old are the doors and windows and do they have low-e glass?
Is there any visible water damage to the walls or ceiling in your house?


Do you have gutters and are they clean, and are they frozen?


Do you have an attic? If you do have an attic have you checked it for water damage, temperature, insulation, or noticed any ice? Water could be seeping in through the roof and melting causing too much moisture in the house. Let me know the answers to these questions and I hope I can help. It is really weird that you are having a humidity problem in west Michigan during the winter.:huh:


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## LateralConcepts (Jun 6, 2010)

I'm interested to see the outcome of this as well. 

It seems to me that West Michigan would be naturally prone to higher humidity being near the great lakes (Lake Michigan).

You either need to increase the heat or remove the moisture

http://www.weatherquestions.com/What_is_dewpoint_temperature.htm

Is your furnace natural gas? 
What temperature do you keep the house at?
Do you have a wood stove?

I think you either need to burn a wood stove or install a dehumidifier.


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## oberkc (Dec 3, 2009)

I have always assumed that high indoor humidity was due to moisture in, under, and around the basement or foundation. Do you have a crawlspace? Slab? Basement? Do you see any signs of vapor barriers? is there any standing water visible under your house?

As others have asked, what are the conditions of your gutters (probably frozen right now)? Do you have good drainage away from the house.


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## gma2rjc (Nov 21, 2008)

gotogregg said:


> Hey Barb,
> This is a very interesting problem. I am very curious to what could be causing this. Your whole house humidifier is off and the damper is closed so it can’t be causing the humidity. It is also cold outside so you are running your heat, right?
> Is there water collecting on all the windows like in the picture of the patio door?
> How old are the doors and windows and do they have low-e glass?
> ...


_*It is also cold outside so you are running your heat, right?* _Yes, the furnace is set at 66°. It's natural gas.

The humidity outside right now is 34%.

_*Is there water collecting on all the windows like in the picture of the patio door?* _ None of the windows have condensation at the top of the frame. They're like the one in the picture below, except for a few older windows that have a lot more water on them. The newer windows, like the one in the picture have low-e gas in them. The older ones probably do not. 









This slider door was installed in 2004. The front door was replaced 1 year ago and the storm door, last month.

There is one window in the house that's probably from the 70's, when the house was built. Five windows are fairly new and 5 are less than 20 years old. I doubt that they have low-e gas.

*Is there any visible water damage to the walls or ceiling in your house? * No water on the walls and no longer any water on the ceilings. I had a problem with that last winter, but it was because of a lack of insulation in the attic, just inside the soffit opening and over the top plate. I fixed that in the fall and haven't had a problem with it since. Here is the thread that discusses that problem.

http://www.diychatroom.com/f19/help-water-droplets-ceiling-59049/

*Do you have gutters and are they clean, and are they frozen?* No, there are no gutters. 

*Do you have an attic? If you do have an attic have you checked it for water damage, temperature, insulation, or noticed any ice?* Yes, there is an attic. I went up there and sealed it 2 years ago and had cellulose insulation blown in. When I was up there before the insulation was added, I didn't notice any water damage and the sheathing looked alright.

Barb


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## gma2rjc (Nov 21, 2008)

LateralConcepts said:


> I'm interested to see the outcome of this as well.
> 
> It seems to me that West Michigan would be naturally prone to higher humidity being near the great lakes (Lake Michigan).
> 
> ...


*It seems to me that West Michigan would be naturally prone to higher humidity being near the great lakes (Lake Michigan).* We do get higher humidity during the summer, but I think any extra humidity in the winter turns to snow.

I don't have a wood stove. I wouldn't mind having one, but for now it's cheaper for us to use natural gas.


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## gma2rjc (Nov 21, 2008)

oberkc said:


> I have always assumed that high indoor humidity was due to moisture in, under, and around the basement or foundation. Do you have a crawlspace? Slab? Basement? Do you see any signs of vapor barriers? is there any standing water visible under your house?
> 
> As others have asked, what are the conditions of your gutters (probably frozen right now)? Do you have good drainage away from the house.


*Do you have a crawlspace? Slab? Basement? Do you see any signs of vapor barriers? is there any standing water visible under your house?* We have a full basement. We have never had any water issues down there, it stays dry. Our soil drains pretty well and the ground is sloped away from the house. I don't see any signs of a vapor barrier.


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## LateralConcepts (Jun 6, 2010)

> *It seems to me that West Michigan would be naturally prone to higher humidity being near the great lakes (Lake Michigan).* We do get higher humidity during the summer, but I think any extra humidity in the winter turns to snow.
> 
> I don't have a wood stove. I wouldn't mind having one, but for now it's cheaper for us to use natural gas.


It may turn to snow outside, but it's turning to condensation inside. Which means the relative humidity is 100%. The dew point then I'm guessing is about 66 degrees apparently. I'm guessing if you turn up the thermostat to 70, there would be a noticeable difference. Also if you have ceiling fans, run them.


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## DexterII (Jul 14, 2010)

Condensation, as you know, occurs where there is a temperature drop, so I tend to agree with Lateral Concepts; I would turn the thermostat up 4 degrees, and run either ceiling fans or room fans, for a week, and see if the situation improves. Also, since you have a basement, I assume that the ducts run between the joists, so I would check the ducts, particularly any end runs, to make sure that there is adequate insulation between them and the rim joists. Further, if your basement is finished, and if it is practical to do so, I would remove some drop ceiling tiles, or whatever other action may be necessary, in order to try to maintain as consistent as possible temperature between the living area and the ducts. Not that any of these by themself are necessarily long-term corrections, but it may very well begin to shed some light on the origination of your condensation problem, so that you can effectively address it.


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## LateralConcepts (Jun 6, 2010)

DexterII said:


> Condensation, as you know, occurs where there is a temperature drop, so I tend to agree with Lateral Concepts; I would turn the thermostat up 4 degrees, and run either ceiling fans or room fans, for a week, and see if the situation improves. Also, since you have a basement, I assume that the ducts run between the joists, so I would check the ducts, particularly any end runs, to make sure that there is adequate insulation between them and the rim joists. Further, if your basement is finished, and if it is practical to do so, I would remove some drop ceiling tiles, or whatever other action may be necessary, in order to try to maintain as consistent as possible temperature between the living area and the ducts. Not that any of these by themself are necessarily long-term corrections, but it may very well begin to shed some light on the origination of your condensation problem, so that you can effectively address it.


On that note, also make sure that there aren't any leaks in your dryer duct.


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## oberkc (Dec 3, 2009)

> I don't see any signs of a vapor barrier


Since you have a basemenet (as opposed to crawlspace) I would expect the vapor barier, if any, to be below the slab and on the exterior of the foundation walls. 

A basement may be "dry" but still humid. Do you have any idea what is the humidity in the basement. Do you run any dehumidifier? 



> Which means the relative humidity is 100%.


I believe lateral concepts is correct here, but suspect this is a very local (within milimeters of the window where air temperatures are much below the rest of the house) condition. I do not believe your house, in general, has near-100% relative humidity.

While turning up the temperature in the house reduces "relative" humidity, it does not remove any moisture (negligible affect on "absolute" humidity). I would therefore be surprised if this noticably reduces window condensation, since the temperature (and relative humidity) near the windows would be minimally affected by an extra four degrees in the rest of the house. 

As a point of comparision, my basement (ohio) has a relative humidity somewhere in the 70% range (higher in summer). Above ground, my house RH can get pretty low (sometimes below 30%). I actually run humidifier during the winter to keep it around 50%. These readings are based upon my thermostat and a wall-hanging humidistat in the basement. 

The fact that you are unable to get your relative humidity below 61% strikes me as indication you are getting moisture from somewhere. If the moisture levels were based purely on exterior air humidity, I would expect interior RH to be lower than that of the exterior due to the higher temperature inside. 

The fact that your RH is higher than outside leads me to conclude moisture is being introduced somewhere. You just have to identify where. Showers? Basements? Dryer vents? Standing water? Unvented combustion (gas stove? Vent-free fireplace?) Some combination?



> No, there are no gutters.


I cannot help but suspect you have high humidity in the basement. Water from the roof discharged near the foundation could contribute to this, even with good slope away from the house. I would be measuring humidity in the basement to find out.

Is it possible that your humidifier is malfunctioning? Can you turn off the water supply to the humidifier (if yes, then do so)?



> On that note, also make sure that there aren't any leaks in your dryer duct.


This strikes me as a good suggestion.


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## Ron6519 (Mar 28, 2007)

Do you have bath exhaust fans? Kitchen exhaust fans? Are they vented to the exterior? Where? 
Have you taken readings on each floor?
Have you taken readings at the vents?
The humidity controller could be bad. I'd try unplugging the humidifier completely.
Ron


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## gotogregg (Sep 16, 2010)

Hey,
I read the older post about the moisture on the ceiling and I think they are related. Is air from the soffit actually getting behind the vents that you added? Does your roof have venting at the peak, ridge vents or turbine vent? If not how does the air in the attic leave the attic?
I put 2 really basic pictures of how an attic should be vented. The air coming in from the soffit needs to flow all the way up. In your picture it looks like insulation is still blocking the airflow. Check your insulation for moisture. Check the nails coming through the roof for water. What is the temperature in the attic now? The only thing I can think of right now is that there is the moisture coming into the attic from outside isn’t venting out through the roof. 
Since there is no water damage on the walls the windows are probably not leaking. The condensation on the interior glass is normal with you humidity level because Low-E reflects heat. Let me know if any of this helps, I am still thinking of more possible solutions and asking some other people.-Gregg


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## 47_47 (Sep 11, 2007)

Ron6519 said:


> Do you have bath exhaust fans? Kitchen exhaust fans? Are they vented to the exterior? Where?
> Have you taken readings on each floor?
> Have you taken readings at the vents?
> The humidity controller could be bad. I'd try unplugging the humidifier completely.
> Ron


I'm with Ron, unplug or turn off the water supply to your humidifier.


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## Ron6519 (Mar 28, 2007)

47_47 said:


> I'm with Ron, unplug or turn off the water supply to your humidifier.


I suggested unplugging the unit from the electric. If the unit runs without water it might damage the motor.
Ron


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## gma2rjc (Nov 21, 2008)

Thanks for suggesting I clean the dryer duct. I haven't done that since last winter and I'm sure it needs it again.

The humidity in the basement is 57% and upstairs right now is 61%. I guess it's called a 'garden level' basement. The bottom of the windows are a little bit above ground level.

I found something that looks like it would turn the water off to the humidifier, but it doesn't stop turning. It's where the water pipe and a thin copper tubing meet and the copper tubing goes over to the furnace.

This is a picture of the stationary side of the slider door. It has no condensation. 









I wonder why there isn't condensation on both sides?

Is it possible that the seal on the sliding side is not keeping the cold air out like it should and is causing condensation to form when it meets the warm air at the top of the door frame.

The seal looks like it's still in good shape though.


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## gma2rjc (Nov 21, 2008)

Ron6519 said:


> I suggested unplugging the unit from the electric. If the unit runs without water it might damage the motor.
> Ron


Thanks Ron. I wouldn't have thought of that. I ran down there to unplug it and there isn't a plug coming out of it anywhere. There is only one outlet on that side of the utility room and the only thing plugged into it is for the little box that sits on the floor next to the furnace that pumps water to the sump pump, maybe when the central air is running.

Is it possible that the humidifier doesn't have to be plugged in?

Barb


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## DexterII (Jul 14, 2010)

It sounds like the valve that you have is very likely a saddle valve, and if so, it's not surprising that it just turns, and does nothing. See if you have another valve, upstreeam, that you can shut off. If not, you will want to address that as a separate issue, but in the mean time, as the guys suggested, unplug the unit. As for the air flow, warm air actually moves toward cold air, and warm air has the ability to hold more moisture than cold air, so it is when the warm air hits the cold surface that the condensation occurs. Not that we're going to have a science test, but it may help you to better understand what is happening. As for the difference in condensation between the fixed and sliding unit, it makes perfectly good sense. As someone mentioned previously (but I can't scrll back up to see who without loosing my text), you are quite likely dealing with a relatively small area of cold air, right at the doors and windows, so although you may not be able to feel the difference, there is enough to allow the condensation to form on one and not the other.


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## Ron6519 (Mar 28, 2007)

gma2rjc said:


> Is it possible that the humidifier doesn't have to be plugged in?
> 
> Barb


 It might be wired directly. The unit needs to atomize the water, so it needs electricity. My mother in law has it plugged into an outlet on the side of the furnace.
Ron


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## gma2rjc (Nov 21, 2008)

*Do you have bath exhaust fans? Kitchen exhaust fans? Are they vented to the exterior? Where? 
Have you taken readings on each floor?
Have you taken readings at the vents? *
The bath exhaust vents out through the roof. Kitchen exhaust vents back into the kitchen, but is hardly ever used. I haven't baked, boiled or cooked anything today.

The humidity at the vents is 57%, the same as the basement.

*I read the older post about the moisture on the ceiling and I think they are related. Is air from the soffit actually getting behind the vents that you added? Does your roof have venting at the peak, ridge vents or turbine vent? If not how does the air in the attic leave the attic?*
Yes, air is going up through those baffles. The insulation you see was stuffed in there to cover the top plate and to keep the cellulose insulation from blowing down into the soffit.

I ended up cutting out the bottom 6" to 8" of all of the baffles - the part that comes down over the top plate. The rest of each baffle is still in place in the attic.

The reason for this is that there is only 2.5" of space in the soffit opening between the sheathing and the top of the top plate. When the baffles were in place, that only left about 1" of space for insulation over the top plate. Post #28 in the other thread has a picture of this.

Cocobolo suggested using the core plast to allow air to flow up into the attic, but also leave room to insulate over the top plate. That worked really well because not only is there air flowing up through the core plast, there is also a small gap between the sheathing and the core plast. There's a picture of this in post #28 of the other thread also. 

All together, I believe there is about the same amount of air going up into the attic as the baffles were providing, because air is able to enter under all of the sheathing instead of just through the baffle. I hope I explained that right.

Thanks for posting the 2 pictures of how the attic should be vented. There are 5 square ridge vents up on the roof. 

The moisture on the ceiling in that thread was due to the lack of insulation over the top plate and over the drywall just inside the soffit opening. Now that there is insulation over all of that, there hasn't been an issue with condensation on the ceiling. I've been checking a couple times a day, just to make sure.

Barb


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## Jackofall1 (Dec 5, 2010)

I would say your door seal is leaking. Is it colder near that door section than the other? 

Can you measure the temp at that location and then compare it to the other side.


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## Ron6519 (Mar 28, 2007)

gma2rjc said:


> I'm trying to lower the humidity in my house and can't seem to keep it under 61%.
> 
> I have a humidifier attached to my furnace. The knob is turned to the off position and the damper is closed.
> 
> ...


 This could be a bad weatherstripping piece. Cold air is getting in and condensing on the door. 
Ron


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## gma2rjc (Nov 21, 2008)

Ron6519 said:


> It might be wired directly. The unit needs to atomize the water, so it needs electricity. My mother in law has it plugged into an outlet on the side of the furnace.
> Ron


I'll go down there and look above the furnace with a flashlight. The outlet the box on the floor is plugged into is on the side of the furnace. 

The only other two outlets in that room have the washer and dryer plugged in and the sump pump and the water heater (which is gas, but there is something in it that requires electricity). 

Barb


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## oberkc (Dec 3, 2009)

> I suggested unplugging the unit from the electric. If the unit runs without water it might damage the motor.


I am not familiar with this particular model, but, based on others that I have seen, I was also concerned about the possibility that water flowing through the unit, even if unplugged or turned off, could cause a rise in humidity. Perhaps unplugging AND shutting off water supply may be a good idea.


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## gma2rjc (Nov 21, 2008)

I don't know if these pics will tell you anything, but these are the only other wires I see.

















Sorry about the tape. The wires were sticking out away from the furnace and I was catching my sleeve on them when I walked past.

The wires under the tape lead down to the little metal box next to the outlet.









Barb


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## Ron6519 (Mar 28, 2007)

There should be wires coming out of the dehumidifier. Trace them to a source. It might be to the transformer next to the outlet. 
Tell us what you find.
Ron


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## oberkc (Dec 3, 2009)

> I don't know if these pics will tell you anything, but these are the only other wires I see.


That top picture is not of a wire, but of a water supply line. The little T-bar handle is the valve that would shut off the flow of water. If this small copper tube is the supply to your dehumidifier, I would shut this down (tighten, like a screw). Like Ron6519 said, however, it may be best to first wait until your unit is powered down.


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## gma2rjc (Nov 21, 2008)

It looks like these are the only wires that come out of the humidifier. I looked all the way around it and on top. One wire goes from that bundle of wires taped to the furnace, down around and behind the pipes and hooks into the transformer next to the outlet box.









The wire that runs off to the right, where the arrow points, goes up and over the top and connects to another wire on top of the furnace that leads to the controller.

















I opened the lid of the humidifier and didn't see any wires in there either. But I didn't pull the filter out to look for wires behind it.

Barb


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## oberkc (Dec 3, 2009)

I assume that the brass device attached to the bottom of the blue-and beige housing is the valve through which water and power flows. Follow the wire from this and temporarily disconnect. The plastic tube coming from the bottom (attached to the black fitting) is likely the drain. Do you see any signs of water here?


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## gma2rjc (Nov 21, 2008)

oberkc said:


> I assume that the brass device attached to the bottom of the blue-and beige housing is the valve through which water and power flows. Follow the wire from this and temporarily disconnect. The plastic tube coming from the bottom (attached to the black fitting) is likely the drain. Do you see any signs of water here?


*I assume that the brass device attached to the bottom of the blue-and beige housing is the valve through which water and power flows.*
Yes, I think the water comes from the copper tubing into that piece of brass and continues up through the black tubing. 

This is with the cover off
















This is with the filter removed.








It looks like the black tubing drops the water into the top of the filter and there are little pieces of plastic that help the water spread across the top of the filter so that it flows down evenly across the width of the filter. At the bottom, it looks like it drains into the tube that goes down into the pvc pipe.

I'm probably wrong though, because it seems like they could have skipped the brass piece and black tubing and just brought the copper tubing up to the top of the filter to do the same job the black tubing is doing. 

Everything in there was bone-dry. I didn't see one drop of water. 

*Follow the wire from this and temporarily disconnect.* I'm not sure if I'd be able to do that. I don't know anything about electrical wires and I'm afraid I would probably do more harm than good. But it doesn't look like there are any wires going up into the humidifier. 

The temperature in the house is 70° and the humidity is 63%.

Barb


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## cocobolo (Dec 16, 2008)

hmmmm....a perplexing dilemma indeed.

I see that nobody has yet mentioned that gas heat also produces water vapor. I have seen in the past where the difference between a gas heated house and either an electric or wood heated house - otherwise the same - had a substantial difference in the moisture content, or humidity level.

It has already been pointed out that warmer air will hold more moisture than cold air. Now let me give you an example to show how misleading this can be.

In my Whitehorse days, when the temperature would get down to bitterly cold, a humidity reading could be either zero or 100%. This is to illustrate that just the smallest amount of moisture, while the temperature is extremely cold, can show up as either reading. The fact is that the air was very dry. Air that cold simply freezes every drop of water, and at night with lights shining through the air, you can see tiny ice crystals floating in the air.

In your case, comparing the inside humidity to the outside humidity doesn't really mean too much. If the inside/outside temperatures were identical, then you would have a valid point of comparison. But at this time of year...

If you have a portable hygrometer, try taking readings at several specific places in the house. Start close to a heat outlet. Try right by the slider where the condensation is. Make a record of the temperature _at every__ location_ and check several times to find an average throughout the day and night. Somewhere in the house you should find a higher humidity level, and that is where you may locate your problem.

I think you will find it near the sliding door - which I doubt seals at all. Don't forget that sliders usually have a small air space all around them and are notoriously difficult to seal. With that much water on the top of the door, it seems obvious that there is substantial cold air entering right there.

If you have other options for entering/exiting the house, I might be inclined to seal up both the outside and inside of that door for the winter and see what happens.

To illustrate another point, right now our cabin inside is 67ºF and 53% humidity. It has been raining here for many, many days and there is water literally running on the ground everywhere here. We leave a kettle on the woodstove all the time to keep the humidity level up. It is the wood heat which keeps the humidity level lower, even though outside the humidity is 82%.

What you need to be looking for is somewhere that cold air is infiltrating the house. As you know I'm pretty familiar with all the work you have done up in the attic. I doubt that is the problem.

I should add that all the previous suggestions are indeed very valid, and I suspect you may end up finding more than a single source of this problem.

If I think of anything else I'll chime in again.


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## oberkc (Dec 3, 2009)

> Everything in there was bone-dry. I didn't see one drop of water.


It sounds like you have done enough to eliminate this device as a source of your humidity. No signs of water anywhere? Good!



> I see that nobody has yet mentioned that gas heat also produces water vapor.


cocobolo is correct. Combustion of hydrocarbons (gas, oil, kerosene)produces mostly CO2 and water vapor. This is why I had asked about gas stoves and gas logs in an earlier post (but apparently this was easy to miss). I would be more concerned about unvented combustion (stove, vent-free gas fireplace) than I would be about combustion where the exhaust gasses are vented to the outside, such as a furnace.


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## rodeo (Dec 1, 2007)

I have to deal with exactly these kind of moisture problems on a daily basis.
It is extremely frustrating to say the least. It looks like you have the obvious stuff covered like fartfans and a cement basement should be adequate.
Range hoods above the stove vented outside are supposedly even more important than bathfans but if you arent heating liquids much then you are OK there.

My main area of suspicion is your attic setup. Tell us more about how you sealed it. Did you lay visqueen plastic? What is your ceiling stackup? Is it drywall covering wood joists filled with fibreglass followed by a layer of cellulose? Although the styrofoam rafter chutes will enable venting of the sheathing, its also sealing off the rest of the attic so that moisture can rise up there causing a "backup" of humidity to build up into the rest of the house. If you also insulated the walls and did other things like new windows, this effect will be exacerbated. 

How about the walls? Is there visqueen in there? any other insulation upgrades?


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## cocobolo (Dec 16, 2008)

rodeo said:


> I have to deal with exactly these kind of moisture problems on a daily basis.
> It is extremely frustrating to say the least. It looks like you have the obvious stuff covered like fartfans and a cement basement should be adequate.
> Range hoods above the stove vented outside are supposedly even more important than bathfans but if you arent heating liquids much then you are OK there.
> 
> ...


Rodeo:

I can partly answer your question on behalf of Barb.

Let me say from the outset, that her house was built by an unscrupulous builder who cut more corners than you can imagine.

However, Barb has done just about everything that is humanly possible in that attic short of putting a whole new roof on. Unfortunately, she wasn't able to add a vapour barrier, and this was just one of many things that the original builder omitted.

If I had been his inspector, he'd still be in jail.

Right on top of the upper wall plate there used to be no insulation at all in many places, this has now been fixed via a combination of blown in cellulose, sprayed in foam and plast to permit airflow below the roof sheathing. We worked out the air volume, and the plast actually supplies as much (or more) than the previous system. That is no longer her problem.

One other thing that has come to mind is that the doors in her place get opened a lot due to all her little visitors. Whether or not this has an effect on the physical moisture coming inside I don't know...but it might. It wouldn't surprise me to find out that in wintertime quite a bit of snow would be tracked inside as well.

I honestly don't think it is as much a humidity problem as it is one of there being a very cold area or two where the condensation is forming. She used to have a far worse problem prior to doing the attic fixing.

Now it seems to be confined to just a couple of small areas. I believe that she will eventually find either some air leaks, or perhaps a small section of wall which is inadequately insulated.

Perhaps some sort of infrared meter aimed at each of the wall cavities in turn will show this up. It may be that a piece or two of drywall will have to be removed (or outside sheathing) to effect a repair if this turns out to be the case.

Basically, it goes back to the original builder. Barb has showed me any number of examples of his poor workmanship....but she is fixing all these shortcomings one item at a time.


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## rodeo (Dec 1, 2007)

OK, those new details help flesh out "the story" or better "the ghost."

So If you dont have a VB on your ceiling, then moisture will migrate its way into the attic. Air sealing and cellulose can stop most moisture migration but enough will still get through into the attic during the cold months and not have any place to go due to the attic being sealed below the rafter chutes.

IMO, for your location and setup - its better to not have a ceiling VB anyway - just a very good air barrier - which it appears you have done.

Have you thought about removing the rafter chutes and allowing the cold air to circulate throughout the attic and let the moisture dissipate that way? 
You will get some xtra windwashing on the cellulose which would reduce it R value some but other things can be done about that too.

BTW, air leaks like say a draft by a window dont usually worsen moisture problems - if anything they help a bit by allowing moist air to escape to the outdoors. Other types of air leaks DO worsen moisture problems like say an air leak exposing a dirt crawlspace to the upper floors via the stack effect - check for the same in your basement. 

Do you live near a lake? Do you have marshy swampy land close by? Just wondering how high up the ground water level is. Also what kind of soil? Sand? Clay? gravelly. All detail like this can be part of the puzzle.


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## oberkc (Dec 3, 2009)

> However, Barb has done just about everything that is humanly possible in that attic short of putting a whole new roof on. Unfortunately, she wasn't able to add a vapour barrier, and this was just one of many things that the original builder omitted.


That is good to know, but perhaps it is time to suggest an alternate view: the discussions about attics and insulation and vapor barriers are all interesting and worthwhile, but it does not (at least in my mind) explain the high humidity levels in the house. From my experience, interior humidity levels during the winter in Michigan (or Ohio, in my case) should be well below the measured levels of over 60%. 

Adding insulation and vapor barrier help minimize energy loss and air infiltration. However, I would expect that air inflitration would actually reduce indoor humidity in this case (winter, dry outside air). As pointed out, vapor barriers also prevent moist air from infiltrating the attic and structure, causing molds and other damage. 

This is all good, but there is still the question of where this interior moisture/humidity is coming from.


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## Jackofall1 (Dec 5, 2010)

How is the humidity being measured? 

Is the instrument anywhere near accurate?

If Barb is not adding humidity to the house I find it hard to believe that there is >30% RH, I would rather tend to believe that instrument being used to measure humidity is faulty. 

At 60% humidy and 65 deg F a window surface would only have to be 51 deg F to reach dew point, given some of the windows in this house are at least 30 years old I would think that they would be sweating to beat the band at 60% RH.

Check the temp at the point where the condensation is forming, my bet is the temp there is quite low allowing the surface to form condensation.


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## Jackofall1 (Dec 5, 2010)

Cocobolo said,

"I see that nobody has yet mentioned that gas heat also produces water vapor. I have seen in the past where the difference between a gas heated house and either an electric or wood heated house - otherwise the same - had a substantial difference in the moisture content, or humidity level."

To this I have to say---- Water vapor created by an indirect fired gas furnace is a product of combustion, if there are products of combustion reaching the heated space then the inhabitants have far more to worry about than moisture, first thing that comes to my mind is CO!!


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## rodeo (Dec 1, 2007)

"where this interior moisture/humidity is coming from"

if the structure is tight enough, thatll cause it - problyy not the case here

if there is no active ventilation system, that could also be enough to raise the humidity to levels like this. 

Are you noticing any mildew spots on the interior walls? Look especially on the bottom corners of rooms against an exterior wall. Another good place to look is in closets that abut an exterior wall especially if there are a lot of boxes stored in it. 

Unvented home designs can work but you need to have your game down 100% with moisture control. Otherwise, you need to vent it.


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## oberkc (Dec 3, 2009)

> if the structure is tight enough, thatll cause it - problyy not the case here
> 
> if there is no active ventilation system, that could also be enough to raise the humidity to levels like this.


Tight structures do not cause high humidity levels, they just keep humid air from escaping. The humidity still must be caused by something. There is something that is raising humidity levels inside the house beyond the ambient levels in the area. Is it your suggestion that normal conditions and activities are sufficient to raise humidity levels in a house to this level (over 60 percent) if not properly ventilated, either actively or passively? Does it concern you that many of the suggestions here are to further "tighten" the structure, further trapping humid air within the structure? My understanding is that most houses (at least those in locations with a real winter) need to have humidity added in the winter.

One source of humidity not mentioned here, but present in all houses: the occupants (think car windows in the winter).


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## gma2rjc (Nov 21, 2008)

Jackofall1 said:


> How is the humidity being measured?
> 
> Is the instrument anywhere near accurate?
> 
> ...


*How is the humidity being measured?
Is the instrument anywhere near accurate?* 
This is what I'm using to measure. 









One part of it (not in the picture) measures the temp and humidity and is meant to be outside so it can send the information inside. But I have both parts in the house still. I got it a couple weeks after Thanksgiving. I think it's accurate. I have nothing to compare it to though.

Here is a picture of the oldest window. I set the instrument on the window sill and it reads 59.7° F, which is about 7 to 8° lower than the rest of the room, and 69% humidity.









Barb


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## oberkc (Dec 3, 2009)

> One part of it (not in the picture) measures the temp and humidity and is meant to be outside so it can send the information inside. But I have both parts in the house still. I got it a couple weeks after Thanksgiving. I think it's accurate. I have nothing to compare it to though.
> 
> Here is a picture of the oldest window. I set the instrument on the window sill and it reads 59.7° F, which is about 7 to 8° lower than the rest of the room, and 69% humidity.


I agree. I suspect that this device is sufficiently accurate for this purpose. I believe, also, that the condensation on the window speaks for itself.

One point, however, is that relative humidity will show up MUCH higher simply by cooling the air. Placing the device by the window may be showing humidity readings skewed by the window and lower temperatures. The condensation on the window may also be creating a high humidity microclimate. What are the humidity readings in the middle of the house? Are they more reasonable (say 40% or below?)

I have no idea what my humidity readings are within inches of a window. The readings I am used to seeing are taken more in the interior of the house, away from windows and other sources of heat or cool.


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## Jackofall1 (Dec 5, 2010)

Based on this information 

Window temp @ 59.7 Deg F (Approximate Dew Point Temp)
Room Temp @ 68 Deg F
The Resulting RH in that room would be 75% (By calculation)

Causing the window to sweat like pictured the only difference being there would be water running down the wall under the window if the ambient condition was @75% RH in the house.

This kind of humidity is difficult to achieve intentionally, there would be an obvious moisture contributor to have this kind of RH at 68 degrees F.

I am familiar with the West side of MI and the ground there is mostly sand, I don't see how sub grade conditions could be contributing this kind of moisture, heck in the summer you have to water the lawn almost continuously to keep in wet enough for green grass.

That being said I still suspect that the instrument you are using is not accurate enough to provide data for this kind of assessment, these instruments will read dry buld temperature accurately, but can be off as much as 20% when it comes to RH.

Oberkc's comment regarding a micro climate is the most likely culprit at that window, as well as at the door wall which is the originating question of this post. You have a cold spot condensating what moisture is in the air.

If you really what to know what your house humidity level is at, buy 2 mercury (alchohol) thermometers, and a piece of cotton, wet the cotton and wrap in around the bulb of one thermometer. Clamp (tie wrap) the thermometers to a piece of wood about 6"L x 1/2" W x 1/2" T with bulbs protruding past the wood, one on each side of the wood, but not touching each other, drill a hole at the end opposite the themometer bulbs so you can insert a rod so that you can spin the assembly in the air for 30 sec's to 1 min, until the temperature on the termometers stop changing or put the therms if front of a fan in lieu of spinning. Read the resulting temps and post them, there are a number of folks in here that I am sure can give you the resulting RH based on the resuting wet and dry bulb temps.

See Attached
http://www.nasa.gov/centers/langley/pdf/245887main_MeteorologyTeacherRes-Ch11.r3.pdf


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## gma2rjc (Nov 21, 2008)

*One source of humidity not mentioned here, but present in all houses: the occupants (think car windows in the winter).*

I thought about that too because I have a daycare in my house. So with the kids running around and other adults being in the house, I thought that could be part of the problem.

But, the front and back doors are opened frequently during the day and, this is probably too much information, but when one of the babies leaves a prize in their Pampers, I open a window for a few minutes to let some fresh air in. So there is dryer air from outside coming in off and on throughout the day.

Last night I checked the humidity at 1:30 am and again this morning at 6:30 am and the humidity level stayed the same and has been the same, within a point + or - all day. So it doesn't seem to be affected by the # of people in the house.

Barb


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## Jackofall1 (Dec 5, 2010)

I have read, that an average family of 4 only adds 2-3 gallons of water to the house atmospere per day, which isn't much at all.


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## gma2rjc (Nov 21, 2008)

oberkc said:


> I agree. I suspect that this device is sufficiently accurate for this purpose. I believe, also, that the condensation on the window speaks for itself.
> 
> One point, however, is that relative humidity will show up MUCH higher simply by cooling the air. Placing the device by the window may be showing humidity readings skewed by the window and lower temperatures. The condensation on the window may also be creating a high humidity microclimate. What are the humidity readings in the middle of the house? Are they more reasonable (say 40% or below?)
> 
> I have no idea what my humidity readings are within inches of a window. The readings I am used to seeing are taken more in the interior of the house, away from windows and other sources of heat or cool.


*The readings I am used to seeing are taken more in the interior of the house, away from windows and other sources of heat or cool.*

Good idea to check there. I set the gadget I'm using on top of my thermostat that controls the furnace. It's in the center of the house. Partly to see if it has the same temperature reading as the thermostat.

The temperature is the same on both, 66°. So it seems like it should be measuring the humidity accurately as well. That is staying steady at 65%.


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## oberkc (Dec 3, 2009)

> The temperature is the same on both, 66°. So it seems like it should be measuring the humidity accurately as well. That is staying steady at 65%.


Which sounds very high to me, and not inconsistent with the calculations of Jackofall. If it were my house, I would be stuck with the same conclusion: there is a yet unidentified source of humidity that should be dealt with. 

You may be able to mitigate some of the associated problems by insulation and moisture barriers and venting and better windows, but the humidity will remain, in my estimation. I would also expect it to get worse in the summer.

Until you can identify that source, I would be running a dehumidifier in the basement. Perhaps you can knock the levels down a bit. This cannot be good for your house and belongings.


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