Pella windows, is this normal??

davenOctober 12, 2005

I have a condo on the Beach that we just purchased. The original windows were Pella with the blinds between two sheets of glass. Pella replaced these under warranty but the new windows are fogging with condensation. Outside temp was 82 and humid with interior around 72 degrees. The windows do not have the interior blinds installed. Although these have only been in for a few weeks, I removed the inner glass pane and mildew/moisture was present. There also appeared to be damage to the track that holds the inner pane.

I left the windows as single pane but the next a.m. I couldn't see out due to condensation on the outside of the windows. This is intolerable for a beach condo. Is the outside condensation normal? Would I be o.k. if the two pieces of glass were in despite the fact that this is not a true double pane system? What advice do folks have for my next move, do I need a different type of window?


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Good morning Dave,

The simple reason that you have exterior condensation on your windows is because the glass has gone below the dew point of the outside air and the moisture has condensed on the glass...depending on the correct environmental conditions, this is perfectly normal.

Any condensation, outside or inside, is "normal" if the temperature of an item (or the air) is below the dew point, in which case you will have moisture being released by the air in the form of condensation.

With the inner lite removed, the cooler indoor air is "contacting" the outer lite and that is allowing the glass to cool below the dew point. Obviously, you must have a high dew point for this to occur at the temperatures that you mention.

Even though not a true dual pane unit, by installing the inner lite you will help maintain the outer lite at a temperature above the dew point...and hopefully, you will eliminate the exterior condensation on the outer lite.

Actually, exterior condensation on the very best dual pane, LowE windows is a "normal" occurance - again, given the right environmental conditions.

You mention mildew and moisture being present when you removed the inner lite; I am assuming you meant between the lites? If so, then the cause should be investigated...if it was cooler outside and warmer inside, then I would suggest that you have an interior moisture issue. But, if the moisture is between the lites and it is warm outside and cooler inside, then you may have another issue involved.

    Bookmark   October 13, 2005 at 11:22AM
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How does one fix the problem of moisture on the windows? I have new vinyl, dual pane windows that get moisture along the edges along with some mold from time to time. I thought new windows would not do this.

    Bookmark   October 17, 2005 at 10:39AM
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The best way to eliminate interior condensation is to lower the humidity level in the house. The thing you need to do is buy a digital hygrometer(device that measures relative humidity) and see what you relative humidiy level is. If it higher than around 35% when you have condensation problems. I suggest you run a dehumidifier, or exhaust fans if the moisture is coming from a bathroom or a boiling pot on the stove.

    Bookmark   October 19, 2005 at 10:13AM
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Lowering the humidity level in the house can surely help in keeping the humidity level down. Most the time it won't help you if you've just had new windows installed. Usually your problem will get better if your home is some what tight from air infiltration. If new windows are still getting moisture then your problem of solving air infiltration has not been solved. Most the time this is do to improper attic insulation and proper sealing. Most attics in the old day never had a moisture barrier installed. So the old plaster and drywall seams are still penetrable by air. When you still had your old windows you were probably leaking in numerous places. When new windows were installed you sealed up the walls and now made a giant chimney. This chimney effect just sucks the air right through your foundation and up through your ceiling. It just flows right straight through the rock. With all the tightening up of homes lately. Many of the older homes are forgetting about the attic barrier. Even with three feet of insulation your going to pull air through. Unfortunately you will need to remove the insulation and caulk the seams and cracks from above. Quite a dirty job! Best thing to do is get a home energy audit to show you where your troubles are. They can show you exactly why your having issues.

One important note for your safety!!! Sometimes when windows are changed and there are still air infiltration issues. The air flow in your home has been disturbed and changed. So make sure you have an HVAC specialist comes out and tests your furnaces combustion and flame after window installation. If the changes are dramatic enough.... all it will take is turning on a bathroom fan or stove fan and your life is in danger. These simple changes in the air can cause these fans to pull the Carbon Monoxide the furnace is suppose to vent out back into the home. We've seen it happen a couple times. So make sure your CO2 monitors are functional and operating. This is just for your own safety!!!!!!!!

    Bookmark   October 20, 2005 at 8:01AM
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Your windows have condensation problems when the temperature of the glass goes below the dew, you basically have two options for stopping condensation formation on the windows.

First, you can lower the dew point of the air by removing excess moisture from your home to a level below the dew point of the temperature of the glass. This will work, but if it gets really cold you might actually get to a point (pun intended, sorry) where you can no longer realistically remove enough water to make a difference...and, if you get to that point, your home may become uncomfortably dry. But, on the plus side, depending on the performance of these new windows, it may be realistically possible to remove enough moisture while still maintaining comfort and controlling condensation. It would depend on how warm the glass inside your home remains when it is cold outside.

Second, you can try to raise the temperature of the glass to a point above the dew point temperature.

Third (snuck in an extra one), you can try a combination of both.

Relative humidity is called "relative" for a reason. Relative humidity (RH) is simply the ratio between the amount of water vapor in the air (also known as vapor density and measured in grams per cubic meter, btw) and the level of water vapor in the air needed to reach saturation or 100% RH...where the air can no longer hold anymore water and it is forced to release some as condensation in this case.

When you have condensation on your windows, then the air in contact with the glass has reached saturation density.

Saturation is based on the amount of water the air can hold at a specific temperature. If the temperature changes and the level of water vapor does not, the RH will change. If the amount of water vapor in the air changes, and the temperature stays the same, the RH will change. Dew point, which is based on the amount of water vapor in the air, or the "actual vapor density", will change only if the water vapor in the air changes.

So, if we vary the temperature in a room, but do not vary the amount of water in the air, then the relative humidity will change, but the dew point will not.

Conversely, if we keep the temperature the same but vary the amount of water vapor, then the relative humidity will change, and so will the dew point.

For an example, lets say that you and your neighbor have virtually identical homes with the same actual vapor density inside the home - 10 grams per cubic meter (for this example) - and, since you like your home cooler, you set your temp at 68 degrees. But, your neighbor likes to keep her house warmer and she sets her temp at 77 degrees. Your trusty hygrometer informs you that your RH is 58%, while your neighbor's RH is 43%...and both figures are correct, despite the fact that it would appear that your home has a lot more moisture in the air than hers based on the relative humidity reading.

The dew point in your home in that example would be 52 degrees...the dew point in your neighbor's home would be - 52 degrees - no difference. If your windows were at 55 degrees you would have no condensation on those windows. If the glass in your neighbor's house was at 49 degrees she would have condensation problems despite the fact that her RH was 15 percentage points lower than yours...go figure.

As rjoh pointed out, using a dehumidifier and ensuring that you use your kitchen and bathroom exhaust fans will help remove moisture from your home. Will it remove enough? Maybe - again depending ultimately on window performance.

As Guy pointed out, new windows actually do seal your house more tightly - one of the main reasons for getting new windows. Oddly, one of the potentially "bad" things about new windows and a not uncommon complaint in the replacement window business is condensation problems caused because your home is much tighter (and the very real potential for back-drafting as Guy also pointed out). The same advantage that helps to keep your energy dollars in the house, also helps to seal in excess moisture that used to leak out thru the old windows. This is not only an issue in replacement windows, it is also an issue in tight new houses where mold and other problems are causing such a stir.

A couple questions - do your new windows have a LowE coating? Are they argon filled?

If you don't mind answering those questions, I can do a couple of rough calculations to get a few numbers concerning the possible interior temp of your windows versus the outside temp...then can work a rough calculation on how much moisture you need to "lose" in order to avoid condensation. Or, at least, we can determine how much you might have to warm up those windows in the winter.

    Bookmark   October 20, 2005 at 8:47PM
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I would also purchase a carbon monoxide detector to see if you have any CO getting into your home. With CO you have moisture from combustion of the fuel which also would contribute to the moisture problem. Also a big contributer to moisture in the home in the winter is a vent free natural gas fireplace or heater. These units dump considerable moisture into the air.

    Bookmark   October 21, 2005 at 12:13PM
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The unit is all electric, no need for CO detector.

    Bookmark   October 21, 2005 at 12:31PM
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Perhaps this is the wrong forum, but I just wanted to let everyone know before they spend the large amount of money on Pella Windows or doors, be aware that they aren't willing to stand behind their warranty. My 2 year warranty expired 5 months ago when we discovered through Pella's own repairman that our window wasn't installed with an expansion joint, which led to aluminum casing separation, and the window not opening or closing properly. I'm in a month long battle with no results, have paid the $75 service call fee just to get something done before winter hits, and all I hear is it's my contractors fault. Pella contractors installed the window and won't own up to their mistakes. Run, don't walk elsewhere to purchase windows. Hope this saves even one person the hassle.

    Bookmark   October 24, 2005 at 12:58PM
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I'm a Pella Certified Installer and distributor. There are no such thing as a Pella Contractor? If you purchased the windows through the Pella Outlet stores. They are responsible for the error not Pella. Pella doesn't own these stores or have any jurisdiction over them. They are privately owned and carry the Pella name. Pella has made it very clear to all of us installers and contractors that they will no longer warranty improperly installed product. I would call Pella and ask them to send you the literature that is attached to each and every window about installation. The expansion joint they speak of is right on the instruction sheet that comes on each window. It clearly states the installer must put 1/2" backer rod in the insulation cavity and final caulk with a good quality caulking. Your exterior siding material can't butt up to the window in any way. There must be at least a 1/2" gap all the way around the window and the siding material. Your contractor carries the burden of improper installation. Get an attorney and get their attention. The longer you sit the more they get away with. Don't let them get away with this one!

    Bookmark   October 24, 2005 at 7:36PM
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We got Pella windows last April, from a Pella store. Had many problems with getting them installed properly. One of the Pella installers told us that there had been a labor dispute within the Pella ranks, most of the experienced guys were gone to be replaced by less-skilled installers. That's what he said, anyway.

Well, getting my installation done properly required many certified letters and many phone calls to their office. It ended with me getting a reduced price. Pella was a hassle but I do like the quality of my windows - they really cut down on the noise in my urban setting. I have the blinds within the window style.

    Bookmark   October 27, 2005 at 1:22PM
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Our Pella windows are 25 years old. Over the past few years we have noticed an increasing problem with condensation between the panes, once the weather becomes cold and the furnace comes on. The condensation forms on the inside of the exterior pane.
It appears that the seal on the removable inside pane is no longer keeping a tight enough seal to keep warm air from inside the house getting in between the panes.
We are very careful to keep the vent holes clear but that doesn't help.
Any suggestions on what material to use to improve the seal on the removable pane - or another way to solve this problem short of replacing the windows?

    Bookmark   October 28, 2005 at 6:22PM
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We just recently purchased a home in June 2005. It is now November and our Pella windows are leaking air terribley along the side tracks where that pulley and string system is. The house is 3 years old and has been vacant for 1 1/2 years. When we called Pella they told us to call the builder. The builder has a one year home warranty which has expired and told us to contact Pella. Pella told us they would send a person out for $125.00 for 1/2 hour to inspect the windows. We feel that that is crazy and that they should stand by their warranty and product and do an inspection at a reasonable cost. Also they told us that they may not even be able to do anything if not within warranty or just normal wear. So now we will have to put that ugly plastic on our dream house windows to keep the cold air out since Pella windows cannot!!!!!! Or find a company that will deliver a quality product.

    Bookmark   November 16, 2005 at 5:51PM
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There is a cost to sending out a rep? That is rediculous! I'd call again and ask to speak to a supervisor. I'd also call the builder and see if he would call Pella as well.

    Bookmark   November 19, 2005 at 9:58AM
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"leaking air terribley along the side tracks where that pulley and string system is."

Your description essentally says that your draft is at the window jambs. Sight unseen, the window manufacturer cannot tell if the air leak is through the window unit itself or through the interface between the window unit and the surrounding frame. Obviously, if it is the latter than the window manufacturer is not responsible, the installer is.

I don't think it is unreasonable for the manufacturer to expect to be compensated to troubleshoot your windows.

FWIW: I agree that the likely culprit is a flaw in the installation and not a manufacturing defect. Units are manufactured under plant controlled conditions, installers are left to thier own devices and have a lot more variability because of the inherent differences in the competency of builders. There are good ones and there are bad ones. Your builder (or whoever installed the windows) should troubleshoot it and then demonstrate the manufacturer's responsibility. If your builder's warranty has expired it seems that you will be responsible for diagnosing the problem and then demonstrating to the appropriate party why they are responsible.

My 0.02

    Bookmark   November 19, 2005 at 1:12PM
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Working in the door and window industry for 30 years plus I see this on a daily basis. When ever some one finds an issue attached to a window they automatically blame the manufacturer. 95% of the time it's the installation. Since I install Pella products daily I see this more times than I care to admit. If your getting a draft around your balance system (Block & Tackle), the string thing. Your leaking in one of two spots. Both are common from poor installation. The first issue is there is no insulation around the window units frame behind your trim (or sheetrock if it returns back to the window). The only way to look is remove the rock or trim and have a peak. The other issue is no shimming done at the vertical center of the window where the two sashes interlock. This is a very critical spot to shim. It holds the reveal of the window true so it can seal completely on all sides. If the gap between your sash and frame is not even and tight to the weather stripping. You will have a breach in your seal and air will infiltrate your home. I know Pella will stand behind any issue related to their manufacturing of the window. They are the first of the big manufacturers to stand they're ground on poor installation. If they know it's an installation error they will fight you tooth and nail. They usually have no problem winning in court anymore. From what I hear the case usually gets booted out. So I would push all your efforts at the builder. If your close to me in MN I will come out for free just to make your builder look like a horses a#@. LMK what you find out!


    Bookmark   November 20, 2005 at 1:54AM
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I know that another issue of leaking windows is dirt and crud on the seals themselves. You cannot get a proper seal if the weather stripping is not fitting tightly in the window. I generally clean mine once a year with a steamer. I was lacking this year and did notice the cold air and steaming of the windows during our last cold snap. I am waiting for my steamer to reheat as I post this. Yes, it makes a world of difference to clean and bring back to life the weather stripping. Soap and hot water work well too.

    Bookmark   November 20, 2005 at 11:57AM
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I would like to thank everyone for there advice and help. Hopefully we can resolve this soon. Enjoy all your Holidays!

    Bookmark   November 21, 2005 at 1:48PM
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Thanks for the info you posted on Garden Web. It addresses a concern that I have and perhaps you can give me a direction or recommendation.

I am in the NW Chgo metro area, and have a quote from Pella in Barrington for 5 Designer Series casements (total 12 sashes) that includes their installation services. The quote does not detail product from labor charges. I asked if the store was independently owned, and was told that they were owned by Pella. That made me question why their installation is only warranted for 2 years, as the products' 20 year warranty is void for improper installation.

Over the last 25 years, I've had 3 Designer Pella patio doors and 4 windows installed by a very qualified independent contractor (who is no longer available). He was very experienced carpenter, I know he installed the products without Pella's clips - I believe attaching directly to the frame. In addition to a quality installation, I also had a significant cost savings as I was able to purchase the windows using the contractor's discount. I have no way of knowing what is the experience and quality of work of the Pella contractors who would do the work - I only know that the warranty will be void if Pella can blame any warranty issue on poor installation.

The Pella in Barrington has not been willing to price the product without cost of their installation. I checked with Lowe's, now selling the Designer, and found they have no knowledge of the product, and not enough experience to know that they have no knowledge, and only gave me much frustration. I also contacted an exterior remodeler who markets Pella, and was told that all my new Pella's will be stocked sized; on reviewing product features with this business, I could tell that they were not knowledgeable on the product. Pella in Barrington stated their windows are customed sized as needed so that I will not be reducing window size, important to me. All sashes are approx 65" long, 3 will be 24" wide and the remaining 9 are 28" wide.

Due to service/labor warranty discrepency, stock vs. custom size determination, and an inability to get product only pricing, I am unable to make an informed decision.

I thank you for your time reading my concern, and hope you can give suggestion.

    Bookmark   December 2, 2005 at 12:17PM
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I am looking into getting Pella replacement windows and was very interested in all your comments. 30 years ago we built a new home with Marvin windows and the wind blew right toward our bedroom windows. On any windy day our curtains would move because of the wind coming in. As soon as we moved into the house I stained and varnished the interior of my Marvin windows. In the winter there was always moisture on the interior of the windows and within a year the interior varnish was peeling. We decided to replace with Pella triple pane. A neighbor and my husband installed the windows so we got to see what the builder did!!! What an eye opening experience.
Basically the windows were smaller than the window openings. The builder had propped the window up to the desired level with 2x4 blocks. There was insulation in the walls but NOT AROUND THE WINDOWS.
We insulated around the windows before installing the new windows. I stained and varnished the interiors myself and after 30 years NEVER saw interior moisture problems or peeling varnish. Once I stained and varnished I never had to redo the job.
Hope this helps someone with window problems. My advice to those who are building a new home or replacing windows is to take a vacation day from work and be there when they are installing your windows to make sure the area around the window is insulated properly.

    Bookmark   February 18, 2007 at 11:11AM
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Most Builders /contractors won't even read the directions, they wrongfully A$$ume that they know how to install Every window. Gave my Installer a Box of Dupont Flexwrap, Dupont Straight Flash & Tyvek tape & he didn't even know how to make the proper cuts for cutting a circletop window with Tyvek House wrap facing!!!\
He never bothered to read the directions. The next day I had a talk with him & printed the directions for his edification. He had tossed the original set;with the handles/literature etc, Pella's install differently then Vinyl windows & differently than most brands. If you don't follow the directions to the letter you INVALIDATE the Pella warranty.

Who in their right mind wants to spend all that $$$ for a top product & then have a 3rd rate Install? The install should be 1st class too. I paid 2 Grand for that window I want it installed & insulated & shimmed or I need to get a new installer.

    Bookmark   April 3, 2007 at 1:26AM
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I've experienced these same issues with my Pella Architect Series windows and doors (cladding problems, seal failure, rotting wood, spotted glass etc.) installed throughout my home in 1995. Pella denies responsibility for these issues. Please check out this website, detailing the various window and door failures/defects: I'm interested in hearing any similar stories regarding your problems with Pella on my website. Thanks for your time! -Adrian Bailey

Here is a link that might be useful: Online Litigation Discovery

    Bookmark   June 30, 2010 at 10:35AM
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We found that there are older mabe 30 year old pella windows in an apartment. Some do not stay up., others we can't open,,,, and some have broken strings..Please help. thanks

    Bookmark   June 3, 2011 at 8:51AM
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