How well should a window be insulated/sealed?

nate379 · Nov 13, 2009

It's been getting down in the single digit temps and I've noticed that the windows in my new house don't seem to be sealed all that well.

I have not paid too much attention on windows in the past so I wanted to run it by you guys before I contact the builder.

The windows are made by Alside. They are single hung, vinyl casing. Low-E Argon filled.

Website: http://www.alside.com/index.aspx?page=510

The issue I have is toward the bottom of the windows I can feel cold air coming in. The windows are collecting moisture on the bottom 1-2" and even icing up.
Right now it's 16* outside, 68* in the house but on the window sill about 4" away from the window it's 62*. When it was 6* a couple days ago it was 57* on the window sill.
Humidity in the house has been staying right around 40%.

Does all this sound normal? I know a window won't be "air tight" but this just doesn't seem right.

Picture I've attached is info from a window when they were building the house next door this summer (same windows). Sorry it's blurry, was taken with my cell phone. I'm not too sure what the info means, so if you can tell me if it's good or bad that'd be awesome.

pseudorealityx · Nov 13, 2009

The window should be sealed better. Mine are pretty bad, but they're 12 years older than I am... so I'm willing to deal with it. Brand new windows that aren't sealing? No good.

B&H · Nov 13, 2009

I think that the relative humidity of 40% inside when the outside temps are 6°F is too high. Are you using a humidifier? Has it been cold outside for long? What type of heat do you have?

Are you sure you are feeling air leaking, or possibly just a cold window? A good window will not have any noticeable air infiltration.

The window sill @ 57° isn't too alarming, IMO, but perhaps the builder didn't get the window openings properly insulated.

I think that if you get the RH lower, your windows will clear up.

Schrodingers Cat · Nov 13, 2009

B&H said:
I think that the relative humidity of 40% inside when the outside temps are 6°F is too high. Are you using a humidifier? Has it been cold outside for long? What type of heat do you have?

Are you sure you are feeling air leaking, or possibly just a cold window? A good window will not have any noticeable air infiltration.

The window sill @ 57° isn't too alarming, IMO, but perhaps the builder didn't get the window openings properly insulated.

I think that if you get the RH lower, your windows will clear up.

good call on the DP
68F/40 DP ~ 43F
translating that to 6F (the humidity is ~homogenous as long as you aren't dehum or humid) yeilds a humid>100, not possible
43F/99% is ~ 43 DP

OP
turn your furnace on
blow smoke where you think the leaks are, see if the smoke passes
turn furnace off, and try the same thing from both sides

nate379 · Nov 14, 2009

It's been around 80% humidity outside.

My thermometer says right now it's 8*, 80% humidity outside. Accuweather says 2* 80% though... Dew point on there is -3*

69*, 41% in the house.

Heat is radiant floor.

B&H · Nov 14, 2009

I wouldn't be too concerned with the outdoor RH. If you bring that air inside and warm it up, the RH of it would be very low.

Yes or no on the humidifier?

Is this the first time the outdoor temps got this low this season? When was the last time you were able to have your doors and windows open?

How many square feet is your house?

The reason for all of the questions is that I fought a similar problem in my house for years. It wasn't the windows that were the problem, but that's where the problem shows up first, and that problem is too much humidity. You will end up with worse problems if you don't get it resolved -- mold, wood rotting, etc.

2 things that stand out to me are "new house" and your window blinds.

Your new wood may not be done drying out yet, and your heavy wooden blinds certainly do a good job of keeping your windows colder during the night.

Are your bath fans, dryer and kitchen fan all vented outside? Boiler and hot water heater venting properly? Ventless gas appliance? I'm just trying to throw out some ideas for you to check.

redvetracr · Nov 14, 2009

B&H said:
The reason for all of the questions is that I fought a similar problem in my house for years. It wasn't the windows that were the problem, but that's where the problem shows up first

care to share how you fixed your problem? I have a similar problem....I am starting to think my problem comes from my crawlspace which I don`t think has any vapor barrier...but curious what you did.

nate379 · Nov 15, 2009

No humidifier. Humidity has been around 40% so I haven't need to use one.

Not sure what you mean on the windows being open. They stayed close all year, but if you mean temp wise I've had the heat on since September.

~1400 ft.

House was done being built 9 months ago.

Yup everything vents outside.

B&H said:
I wouldn't be too concerned with the outdoor RH. If you bring that air inside and warm it up, the RH of it would be very low.

Yes or no on the humidifier?

Is this the first time the outdoor temps got this low this season? When was the last time you were able to have your doors and windows open?

How many square feet is your house?

The reason for all of the questions is that I fought a similar problem in my house for years. It wasn't the windows that were the problem, but that's where the problem shows up first, and that problem is too much humidity. You will end up with worse problems if you don't get it resolved -- mold, wood rotting, etc.

2 things that stand out to me are "new house" and your window blinds.

Your new wood may not be done drying out yet, and your heavy wooden blinds certainly do a good job of keeping your windows colder during the night.

Are your bath fans, dryer and kitchen fan all vented outside? Boiler and hot water heater venting properly? Ventless gas appliance? I'm just trying to throw out some ideas for you to check.

aim · Nov 15, 2009

I don't have any science to back this up but I've always believed that it takes a couple of years for a new house to dry up. These days houses are built SOOO tight that it may even take longer. My house was damp and I had to run a dehumidifier all winter while burning propane. I heat with wood now so that problem is over.

nate379 · Nov 15, 2009

I started doing more research on it because I was cleaning and noticed that the window stoles are already being ruined by this moisture!

Everything I had read before said 35-40% humidity is normal, but I found some info on a window webpage that says otherwise:

http://www.windowworld.com/resources/repair-center/prevent-fogging-condensation.php

Lowering the humidity is still not going to fix the drafty windows though. The water that is collecting on the windows and dripping on the stole is turning into ice! That just doesn't seem normal... I dunno.

I'm going to talk to my folks later today and see what they think about it.

walrus · Nov 15, 2009

nate379 said:
I started doing more research on it because I was cleaning and noticed that the window stoles are already being ruined by this moisture!

Everything I had read before said 35-40% humidity is normal, but I found some info on a window webpage that says otherwise:

http://www.windowworld.com/resources/repair-center/prevent-fogging-condensation.php

Lowering the humidity is still not going to fix the drafty windows though. The water that is collecting on the windows and dripping on the stole is turning into ice! That just doesn't seem normal... I dunno.

I'm going to talk to my folks later today and see what they think about it.

It depends on how cold it is, I doubt your Windows are more than R3, warm moist air hits that cold surface and you have condensation. I get ice on my windows in the bathroom during the winter when its really cold out. I get it in my solarium also but those windows are really cheap. Both areas have a higher humidity than the rest of the house. I laugh when people reccommend high humidity in a cold climate during the winter, just asking for trouble

B&H · Nov 15, 2009

Nate,

Drafty windows will actually lower the humidity in your house. That's why so many people "back in the day" used humidifiers, because bringing outside air in that's has a RH of 80% @ 0°F will be between 10-20% @ 70°F, and not too many homes were sealed well because energy was so cheap.

I can't tell from where I'm sitting if your windows are truely leaking air or not, but I will agree that if you don't do something quickly, you are going to have problems.

I'd contact your builder for sure.

The humidity chart you linked to is more representative of where your humidity needs to be.

1400 SF and radiant heat makes it tough to get rid of humidity generated by everyday living - cooking, showering, etc. That's why I asked about when the last time your windows were opened. Air exchanges now become important, esp since your house is new, small and there is a season change.

In the meantime, before you get someone to look at it, you may want to actually use a de-humidifier.

My house is 1200 SF plus a full basement. It was built in the 50's and has NG forced air heat. After we insulated it and installed good windows and doors, we had a humidity problem. The window people and HVAC people couldn't figure out where the moisture was coming from, but I did (accidentally).

Our NG furnace and NG hot water heater vent up the chimney. If the furnace was off, and the hot water heater was on, the chimney would backdraft when the kitchen exhaust fan was turned on. The hot water heater was basically venting into the house! The kitchen fan vents outside and is 300 cfm. Also, if the NG clothes dryer was on and the bath fan was on, again, the hot water heater would backdraft. Yuk!

So I installed an 8" duct from the outside to the furnace room, with a 300 cfm make-up fan and a switch next to the stove. When my wife uses the kitchen fan, she turns on the fan for the make-up air. I also have a weighted damper, so that the "system" can be passive when using the dryer or bath fan.

After installing and using the system, my humidity problems disappeared in a couple of days. That was about 10 years ago. What seems stupid is spending a lot of time and money on tightening up our home, and then having to force 300 CFM of cold air back into it! But a little less efficiency is much better than a sick house.

Redvetrcr, a crawl space w/o a vapor barrier on the ground is a big no-no.

walrus · Nov 15, 2009

B&H said:
In the meantime, before you get someone to look at it, you may want to actually use a de-humidifier.

I'd look at a heat pump hot water heater instead of a dehumidifier. I use one for most of the year and it works great. Not only does it remove humidity from the air but it saves me 30 or 40 bucks a month on electricity bill compared to running a regular electric hot water heater.
Made in Maine also

http://www.nyle.com/?q=node/71

Schrodingers Cat · Nov 15, 2009

something is adding (or retaining moisture you add, showers, cooking, etc.) in the house...
using the exh fan when you cook and bath helps alot...

8F/80% rh/~3F DP

the house dew point should be very low ~ to the outside, maybe 10-20F higher or so...68F/7%/~4F DP, so even if your DP is ~30F inside at 68F that's only 25% rh...

the house may not have enough ventilation...perhaps a small exhaust fan with a heat exchanger for the OA...AK is a tough place to design HVAC/controls for...

my house builds up moisture over the winter also, so the first time I turn on the cooling in the spring I get some 'sweating'

Kevin54 · Nov 16, 2009

At 40% humidity you are too high. You want less than that or you will get condensation on the windows. We had new windows installed and the first year they did the same thing. Humidity was too high. I thought it was a cold draft coming in and the cold meeting the warm causing it. Wrong. Check with any reliable window company and they have letters of explanation on moisture on windows. If I can find mine, I'll scan it and e-mail it to you. Now you need to know the source of the humidity in the house. If you have an add-on humidifier on your furnace for wintertime, you may want to cut it back some. If not, then you need to see why the humidity is so high. Bathrooms not venting properly, as others have stated...house too tight, which is not good for a person anyways. Plants being watered. Many things can cause it.
Now on the other hand....the ice buildup on the window sill. It sounds to me like there is not enough insulation around the window. Ice is not normal with todays windows. Does it do it on ALL windows or just one? It may be the fact that if it is one window only, then it could possibly be bad from the factory. It also looks like a marble sill or vinyl sill? I would pull the piece of moulding off underneath the sill and make an inspection.
If your utility company is a rural Co-Op, give them a call and see if they do energy audits. Ours did our house for free last year. Blower door test, thermal imaging, air leakage, etc. Surprisingly our house passed very well. Moreso than expected.

nate379 · Nov 16, 2009

I can bring the humidity down to whatever I want really. The #2 bathroom fan is hooked to a de-humidistat. Makeup air comes from an interior wall which is opened at the top to pull from the attic (which is vented).

I kicked it down to 30% today and it hasn't really helped with the window situation.

I was talking to my folks today and they said my situation is not right. They normally have the house around 50% humidity and get a little bit of sweating, but nothing too much. Their house is sealed very well.

nate379 · Nov 16, 2009

They are R3.2 (U factor 0.31)

walrus said:
It depends on how cold it is, I doubt your Windows are more than R3, warm moist air hits that cold surface and you have condensation. I get ice on my windows in the bathroom during the winter when its really cold out. I get it in my solarium also but those windows are really cheap. Both areas have a higher humidity than the rest of the house. I laugh when people reccommend high humidity in a cold climate during the winter, just asking for trouble

rieferman · Nov 16, 2009

Nate wrote:

The issue I have is toward the bottom of the windows I can feel cold air coming in.

Regardless of humidity, wouldn't the fact that he can actually feel air movement be the thing we should focus on fixing? I know when I moved into my farmhouse (which has newer vinyl replacement windows) I could feel air movement, and was getting condensation.. I popped the trim off and squeezed in expanding foam (be careful to use the stuff meant for windows and doors), put the trim back in place. In my scenario, that fixed the issue.

Also, I always understood 40% relative humidity to be a healthy and comfortable level to keep a house at. Any lower, especially in the winter, and your skin and sinuses dry out too much. All the links I just googled note the same thing. Am I looking at the wrong number?

nate379 · Nov 16, 2009

The info I read varies, but 40% seems to be an ok humidity.

My folks think there is no insulation/foam around the casing as well. The window mouldings are a one piece unit, not exactly the easiest thing to remove (probably going to damage it some). I'm going to let the builder fix the problem since they are to blame anyhow.

Schrodingers Cat · Nov 16, 2009

68F/50% rh is a dew point of ~49F

so if you window surface is less than 49 you will get condensation...

here's a calculator to play with
http://www.builditsolar.com/References/Calculators/Window/condensation.html

what's happening semms to be normal with that high of a humidity

nate379 · Nov 20, 2009

Well since I wrote the first post, I have had the humidity at 30% and the problem hasn't been any better. Granted the past few days have had a high of maybe -1* and lows of -15*, but still it doesn't seem normal.

I have lived in many houses that were well insulated and it wasn't a problem like this. I know a bit of condensation is normal, but this is puddling on the sole and dripping on the floor even when I wipe it down at least once a day. :wtf:

The builder's rep called and left a msg basically saying that because the house is sealed well that it will do that and I am responsible for the window soles. They are going to get the window pro at the local lumber yard (where the windows come from) to come take a look though.

walrus · Nov 21, 2009

All I can say to that is wow, thats an issue with moisture in a house like I've never seen. Are all your windows like that? I'd put a layer of plastic on the inside of that window and see what happens. They make a clear plastic that you use a hair dryer to shrink to the window frame. Has to be done on the warm side. Probably hate the look of plastic but if this a temporary problem if might save your sills?

How thick are your walls?
If the house is less than a year old, could be the moisture is coming from the wood or foundation? You on a slab?, curing concrete might do that to a house. Any vapor barrier under the slab?

You might have to get a dehumidifier or maybe an air to air heat exchanger if your house is that tight.

nate379 · Nov 21, 2009

Yes every window in the house is like that. The walls are 2x6, R-21 insulation. Slab has plastic and 2" foam under it (radiant floor heat)

Interesting thing, last night it warmed up to 10* and it's snowing. The windows are almost all cleared up.

As far as the dehumidifier, the humidity in the house is so low right now that it is almost uncomfortable. My laminate floor even shrunk to the point that there are small gaps between some of the planks.

The windows icing up aren't the endof the world, but the fact that it is ruining the window soles really *****!

tdkkart · Nov 21, 2009

Your windows look to be set out in the wall a long ways, I wonder if the cold moist air is getting trapped in the window frame area and making the problem worse??
Do you have ceiling fans to move the air around?? Might help to circulate the air in the room to try to get that cold air away from the windows??

B&H · Nov 26, 2009

Wow! Ick is more like it.

Ezzie · Nov 26, 2009

walrus said:
...or maybe an air to air heat exchanger if your house is that tight.

Bingo. This is your answer. These are very effective in Northern climes such as where you live if your house is really air tight (well installed vapour barrier and very few leaks). What you could do is have an energy auditor come and do a blower door test to see how air-tight your home is. This would also validate whether the windows are leaking or not.

I first started using an air exchanger in the '80's and they are very effective as a way of helping control the humidity. I did a remodel of a 100+ yr. old house and used urethane foam to seal all the walls and attic, thus creating a virtually air tight envelope. I installed new triple glazed windows at the same time and went all electric for heat source. The result was intolerable levels of humidity when the weather got cold. No way for the moisture to escape. The air-to-air heat exchanger (sometimes called an HRV - heat recovery ventilator) allows some of the heat to be captured from the out-going stale warm air and used to pre-heat the incoming fresh cold air.

nate379 · Nov 26, 2009

Not sure how that would help if the humidity it already very low?

Looked into it when I first bought the house and was looking at around $7k all said and done.

Ezzie said:
Bingo. This is your answer. These are very effective in Northern climes such as where you live if your house is really air tight (well installed vapour barrier and very few leaks). What you could do is have an energy auditor come and do a blower door test to see how air-tight your home is. This would also validate whether the windows are leaking or not.

I first started using an air exchanger in the '80's and they are very effective as a way of helping control the humidity. I did a remodel of a 100+ yr. old house and used urethane foam to seal all the walls and attic, thus creating a virtually air tight envelope. I installed new triple glazed windows at the same time and went all electric for heat source. The result was intolerable levels of humidity when the weather got cold. No way for the moisture to escape. The air-to-air heat exchanger (sometimes called an HRV - heat recovery ventilator) allows some of the heat to be captured from the out-going stale warm air and used to pre-heat the incoming fresh cold air.

walrus · Nov 26, 2009

tdkkart said:
Your windows look to be set out in the wall a long ways, I wonder if the cold moist air is getting trapped in the window frame area and making the problem worse??

Actually I think this makes alot of sense, not sure how you remedy this though

B&H · Nov 26, 2009

That's a good possibility. With radiant floor heat, there isn't any air blowing around either.

Nate, are there similar style homes built in your neighhood? If so, are they having the same problem?

nate379 · Nov 26, 2009

My neighbor and yes, same problem.

Windows are normal ones, walls are 2x6, maybe that's why it seems the framing is deep? It's only ~4" from the window to the wall.

walrus · Nov 26, 2009

nate379 said:
My neighbor and yes, same problem.

Windows are normal ones, walls are 2x6, maybe that's why it seems the framing is deep? It's only ~4" from the window to the wall.

My windows are deeper, 2 by 6 with inch of foam on inside, no radiant , not as cold , most of my windows are on south side, none on north

B&H · Nov 26, 2009

Nate,

In your first post, the RH was 41% and the outdoor temp was 9°F, and the windows and sills were a mess.

Now you state that at 30% RH and 10°F outdoor temp that your windows are almost clear. I think you are making progress!

Was your neighbor's house built at the same time? Do you know of a similar house built 2 or 3 years ago that has had more time to "dry out" from being new?

Are the 0° to -15° temps normal for your area, or just a really cold spell?

nate379 · Nov 27, 2009

Yes, the weather is all crazy here!

It went from -15 for about a week and then one one day it goes to 25*. That lasted a few days.

Yesterday it snowed 4", then warmed up to around 40* and rained, melting alot of the snow (had about 8-10" on the ground)

Now it's back to around 30* and snowing HARD.... supposed to snow 10"

I still think the air coming in from the around the frames is causing part of the problem. Builder has not returned my calls or emails at this point. One window frame was pulled a while back because it was sitting crooked. I am thinking of pulling it back out just to see for sure if it is insulated.

My folks live in northern Maine and even when it's -20* outside they just get a little bit of condensation... that is with the inside humidity sitting around 40-50%. Also it's 62.4 right near the window at that temp.... where I am sitting around 57* at ~-10* about 4" from the window..... hmmmmmm.....

I mean I don't think I should feel cold air sitting 4-5ft from a bank of 4 windows (see pic)

Keep · Nov 27, 2009

From the sounds of it there is more than one thing going on here. Humidity to high in the house and probably not much insulation around those windows.

We had our windows replaced a year ago. We were having the same issue with ice build up on the windows. Of course our windows were 20 years old and were not sealed as well as they should have been. But the biggest culprit was the fact that the builder did not use much if any insulation around the window. Our original windows were top of the line (in 1987) casement windows and according to the previous owners from day one they had this issue. They had tried caulking and all sorts of "fixes" and never sorted it out.

Once the old windows were out the installers pointed out the lack of insulation around the old window frames, they sealed them all up with spray foam and no more ice build up on the windows.

They also recommended in winter to drop the humidity inside to around 20% and once a month or so open up a window to bring some fresh air in.

I would pop off a couple pieces of the bottom casing and take a look to see if there is any or enough insulation.

nate379 · Nov 28, 2009

Yup, think I will do that tonight or tomorrow. The casing is all one piece so it's a bit harder to pull apart.

How well should a window be insulated/sealed?

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