What is your interior humidity level?

More often than not you house has too much humidity inside and the windows re were it shows up. As Jerry asked what is the humidity inside your home?

45%. We were told to keep it at this level so woodwork doesn't crack.

We usually keep it below 30 in the cold part of the winter and move it up in the spring to about that level.

To be fair, interior condensation is usually the result of high levels of humidity on the inside of your home. Inefficient windows will make it worse dont get me wrong.

Actually, windows that are doing their job will make the issue more visible to you by collecting that excess moisture to the surface of the glass. Almost like a magnet. That is what you are seeing.

Water condenses on the windows when the temperature of the glass drops below the dew point of the air. If you look at the owners manual of your humidifier, it will state recommended settings vs outside temperature. The chart shows typical settings. Keep in mind also that digital controls on humidifiers can vary by as much as +/- 10%.

You really should not have to keep your rh below 45% with new windows. If you still experience problems, you either have a poor installation that keeps the product from operating optimally, or you chose a product that does not offer very good thermal performance. That latter opinion may not be popular and I have to agree that Marvin generally makes a nice piece, but there are thermally superior choices available with better condensation resistance ratings. Most wood windows leak air like a sieve, so that would be a contributing factor as well.

I would encourage you to read published material regarding condensation that cover the industries stance on the issue and not just Marvin`s. Try GANA, glass.org, or BBB. They will explain interior air flow in the home and other contributing factors.

+1 to the other suggestions here.

I would reduce my rH levels to start with.

Next, have the windows checked for properness of installation and look for misalignment at the meeting rail and weatherstripping interfaces.

If the windows are hung right, you can get excess leakage at those areas and get condensation, regardless of the efficiency of the glass/frame/etc., if you have outside air infiltration.

Lastly, make sure the blinds, drapes, and window coverings at the window are open and allowing air to circulate at the window.

Thanks for all the good advice. We had a senior Marvin rep here last week and went through each window. If there were any issues he would have caught them.

I'll read up on the literature and bring this up to my builder.

Thanks.

High humidity in the house can lead to other problems that will not be as apparent as what you see on the windows. You will have moisture that makes it past your vapor barriers your exterior walls and condense on the interior side of your wall sheathing. Keeping the RH lower reduces this. I have a LOT of wood in our house. As the seasons change you can hear it pop. I keep the RH set at 35%, we are in Georgia so the exterior temperature is rarely cold enough to cause condensation. The accuracy of the controls on your humidifier should not be overestimated. Most people laugh at this, but the only way to really check the dew point and Relative humidity is using this method: In a small light weight thin walled container, (preferably metal like a mixing bowl) filled with water, add ice while stirring with a thermometer. The instant water forms on the outside of the container, note the temperature on the thermometer. This is your dew point. Then use the attached chart to determine Relative Humidity (assuming you are fairly close to sea level), you can then check this against your humidifier control. You can also use Sling psychrometers, but they are not that accurate, battery powered psychrometers are ok and old fashioned calibrated camel hair analogue gauges are good if you can find one.

I would to offer a solution to your dilemma. If you try www.windowinsulators.ca you will see the answer.
A rh of 45 % is a GOOD THING !!!! An acrylic window add on to your present window will fix everything. We test the acrylics to minus 75 F with dry ice and achieve an R 6.5 . Bear in mind the best 3 pane windows with dual 1 / 2 inch spacers and low E with argon and krypton gas.
Contact us and we can ask you some questions about your interior environment to give you the best path to follow
1 807 627 4631

I am sorry sir, but that is incorrect.

As a previous poster mentioned, regardless of the condensation potential on the windows at the higher rH levels, too much humidity can create a host of other issues in the home beyond the visible demonstration of the the windows sweating.

Nothing about an interior storm does anything to address that either.

Many interior storms that I see also exacerbate the issue by limiting the drying and air circulation at the window surface.

Your advice is flawed on so many different levels that I felt it needed address.

Happy Thanksgiving.

+1 WoW

and a Happy Thanksgiving to all!!

Windowsonwashington , I know that you are basing your comment about interior storm windows on the what you have seen . What we propose is something you have not seen. A PROPER install of these will magnetically seal 100 % of the inside damp air from touching the cold glass. no air = no sweating

windows,

I know exactly what you are proposing and the fact of the matter is they do not work in this case and your recommendations of 45% rH is completely incorrect as well unless you want the client to rot their house from the inside out in a colder area of the country.

Humidity and interior moisture is one of the bigger issues out there in a cold climate and magnetically attached interior panels are not what most people determine to be aesthetically pleasing or even and option.

Your claims or R-Value are completely inaccurate as well.

It is safe to assume that a double pane wood window with Low-e/argon is going to be about a U-Factor of 0.30 or R-Value of 3.33.

Are you trying to tell me that adding an acrylic panel, even perfectly sealed, is going to nearly double that number?

When a trapped air space (completely static) is R-1.0, you are telling me that a layer of acrylic with no coating on it adds R-2.5?

I am sorry but that is not going to happen and you can claim whatever you want to in this case but science and facts do not support your claim.

I live in North Dakota, so too much humidity in the house is quickly evident with condensation on the windows. We had 3 large aquariums, and no exhaust fans in the bathrooms (we don't open the windows in the dead of winter). Excess humidity was definitely an issue - and in February, 45% was WAY too much!

Three years ago, we installed exhaust fans in the bathroom, got rid of the largest aquarium, and even run a dehumidifier in the winter. It has made a world of difference in the amount of condensation on the windows - and as others have said, it's the moisture issues you can't see that are a far more serious problem.

Seeing water vapor on the windows is a good thing - it alerts us to a potential moisture problem.

Don't have much to add other than that your first course of action should be to reduce that RH. If you still have issues, call the marvin rep back out. Often times things can be overlooked until they are identified as a complaint. You definitely DO want to get this addressed one way or the other as water + wood windows = bad news.

I have the exact same problem as threeapples. I just got new Marvin windows put in my sunroom and now that the weather is getting colder every day I can wipe off condensation right between the upper and lower sash. What worries me is that the water is always against the wood. These windows were very expensive and I'm concerned that if this continues the wood will rot prematurely.

Get a relative humidity gauge and see what your moisture levels are like inside the home.

+1. Exactly the same advice as above. lkbum posted some great charts for reference to show when and how the condensation will develop.

Being that this is in a sunroom, I'd imagine that it is a cooler than other areas of the home, which makes condensation easier even at lower levels of RH. Get the temp up in there or the RH down... or both if needed. Do these windows have treatments over them? If so, opening them would help warm up that glass.

We just completed sealing (1.5 ACH50) and insulating our older home and would love some help solving our condensation problems. All the windows were replaced by low-E, argon filled Marvin windows. Marvin was chosen in part because their windows satisfied the requirements of the local historic commission. Now we have ice and water condensing on the lower part of the sashes. The outside temperature is between 0 and -18F, which is not unusual in this area. The relative humidity inside ranges between 39% and 45%. All the windows surfaces are free of treatments. We have a condensing dryer, bathroom fans, HRV units, and kitchen venting so we shouldn't have significant contributions of humidity from these sources. Increasing the temperature inside or running a dehumidifier (to obtain 20% RH) might work but the whole point of this project was to reduce energy consumption! Are exterior storms the way to go?

Humidity is way, way, way to high for those temps. You have to see if exterior storms will work or are even allowed with the Low-e coating. They will probably work but need to come off in the Spring and stay off when it is warm.

Where is all the moisture coming from then? Is the home on a crawl space? Has that been retrofitted if it is?

+1. Storms may work, but could cause other issues. Either way, they do not address the actual problem which is that the RH is far too high for those temps, and really any winter temps for that matter

We are not sure where the humidity if coming from - maybe a variety of sources including the outside air. Setting aside the desire not to run more equipment, our relatively new dehumidifier doesn't seem able to pull the RH below about 35% at these temperatures. Maybe there are better ones out there.

The project was a whole house retrofit so the basement was insulated. The RH there is in line with the rest of the house. Is there an easy way other than comparing measurements of the RH in the basement and elsewhere to check whether the moisture could be coming from the (concrete) basement floor? Thank you for your replies.

Storm would be a viable option, Marvin makes there own and other would work.

Don't think you'd need a low-e coating on them if the primaries have Low-E.

Not sure why one would have to remove the storms in the spring???

Not sure the storms would lower the surface temp enough to eliminate condensation , may try 1 or 2 first ?

Storms should be removed or vented in spring to prevent excessive heat build up between the units which can cause problems. Some manufacturers will void the warranty by simply installing a storm. Secondly, a storm is treating a symptom. Like taking Advil for a torn acl. Lessens the pain but doesn't do anything to fix the actual problem.

On that note, given that this is an older home, it's not likely that you have moisture being generated by a curing foundation, nor is it possible that moisture is coming from the outside air since it is drier than the inside air. If the air sealing was done properly, you simply have a tightly sealed home that needs some adjustment to, or additional method of air exchange in the home to decrease the amount of moisture. Moisture is generated in the home by people, pets, plants, cooking, showers, etc. In other words, it's more likely that your issue is in moisture RETENTION as opposed to moisture GENERATION. I would talk to the energy consultant that performed the blower door for suggestions, as they are familiar with the specific circumstances of your home.

It's really hard to get a house to that humidity level when it's that cold out. From what you posted, your most likely culprit is your condensing dryer. Only source you've mentioned that can put that amount of water into the air.

I'd go with dryer as well, maybe open window in laundry when drying?

don't think there is an issue with adding a storm to the Marvins since they do sell them at least for some of there lines. I'd disagree with treating it as a symptom since you would be lowering the surface temp of the prime window which could be a solution. The two answers are lower surface temp or humidity neither are Advil if they work

Most certainly is Advil. Windows are just the most visible spot to manifest an issue with rh that is too high. There are other major issues that could be going on with indoor air quality, hidden condensation on other organic surfaces, etc, by having too much moisture in the home. I realize that you like to be the voice of dissension Todd, but that advice is irresponsible. The problem is not just some moisture moisture on the Windows, again, that is only a symptom of a larger issue.

As I stated earlier, the best course of action would be to get the RH levels to an acceptable level for the conditions, and contacting your building analyst/energy consultant as opposed to leaving the health of your home and family to Internet speculation would be advisable.

I don't think there levels are at critical health levels and are Within a reasonable range. The level does need to be lower in the winter sometimes if condensation on Windows is a problem. Storms could be a viable solution.

45% RH with subzero temps outside is not a concern? What would be a concern Todd? That's pretty extreme and not within a normal range by any credible definition.

I'd also add that given the homeowners comment about the RH being consistent on multiple levels of the home, that would make the dryer a less likely cause, but again, first hand assessment by a qualified professional would be the be preferred course of action.

I see that the solution isn't immediately apparent from a brief description. If we track down the problem and determine a solution I'll let you all know. Thank you again for your advice.

I have seen dryers located in basements cause major condensation problems on the the2 floors above . One house was a duplex withe separate entries and heating systems.

Completely acknowledged Todd. Experience and logic would dictate however that the RH would increase as you move closer to the source. Never said it couldn't cause high RH two floors away, only that it is unlikely that the readings would be consistent as the OP alluded to.

Old post but in any new construction: walls have a moisture/vapor barrier of either plastic sheeting or aluminum foil sheeting. The ceiling does not have a vapor barrier THUS enabling excess moisture and the presence of the pressure from too much moisture to move up through the ceiling and out through the attic. And depending on how your house is built and insulationed 45% moisture is not too much even when exterior temperatures are below 20 degrees. You can built a house that will easily accept RH levels to 60% when outside temperatures are below freezing. The problem is most builders dont have this type of experience or knowledge to do this, thus the reactions of most posters here.

60% RH....? You house walls and ceiling would look like this.

I have to echo what both HomeSealed and WoW said.

customsofa, the information in your post is dangerously wrong. What you describe is a disaster waiting to happen.