Window Condensation Explained & How To Avoid on a New Build

Matt explains in detail what causes condensation in your windows and how to avoid it.
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[@pklemm1]

I had condensation issues a few weeks ago. I live in the northeast and the home is 4 years old. My indoor humidity was 50 and I started running a dehumidifier at night and wow in the morning almost no condensation on the windows. The humidity ended up coming down to 37-40

[@bholowick]

I live in Manitoba, Canada (we usually get a few weeks of -35°C each winter). Most houses here have basements and there is typically a floor register below each window on the main floor. This helps to reduce the amount of condensation that forms on each window. I also remove the bug screens from each window in the winter which helps increase airflow across the glass. The humidity in my house gets extremely low in the winter, and I have high quality triple pane windows, and I still get condensation on the windows. Our window frames and jamb extensions are PVC, so they don't get damaged by condensation.

[@shellderp]

Yep I noticed in my house every register is by a window. I also remove the bug screens as I noticed the windows that open have much more condensation. I made the mistake of installing cellular shades, they insulate great in summer but make my windows extremely cold, to the point the entire window is wet.

[@Mark-vx5dt]

Another Manitoban here with the same experience. Humidity is currently low 30s. It’ll get a bit lower by January. I get a small amount of condensation on a few of my windows. Before I had a HRV I would get a lot of water pooling and ice freezing on the inside of windows!

[@j.frankparnell3087]

In my 1952 Alberta house the original HVAC system had the air returns around the perimeter and the heat vents on the internal walls. This setup allowed tons of window condensation during winter. About 20 years ago when the furnace was replaced, the HVAC company also reversed all the ducting so that the air returns are now on the interior walls and the heat vents are now around the perimeter. This had a profound effect and resulted in much, much less condensation.

[@thuster123456789]

@@j.frankparnell3087they don’t call them tin bashers for nothing!

[@thuster123456789]

@@shellderppull up the blinds 6” in the winter so the bottom of the window gets some warm air circulation.

[@Dominicanito6]

Just a small critique on your method for using the thermal camera coming from a certified infrared thermographer. Glass is highly reflective and will reflect the infrared heat from the room back to the camera. As you can see your heat signature is being bounced off of the glass and showing up on the camera. To get an accurate measurement of the thermal signature of the window you want to use a piece of white electrical tape and a piece of black electrical tape on the glass pane so that it increases the emissivity of the surface. Low emissivity surfaces such as glass need to be manipulated with an additional surface to allow for proper thermal imaging. Otherwise the video is spot-on. Great work is always Matt!

[@buildshow]

Excellent tip. I’ll do that. Thanks

[@tweake7175]

The other factor here is air movement across the glass. If you have curtains stopping the airflow you will get far more condensation. One of the tricks they do here is to use the ventilation system to blow air behind the curtain.

[@steverogers8163]

yes this. I have a horrible 1970s aluminum window. Horrible condensation buildup on it, but if I set some fans up to constantly push air across it there is no condensation. An easier solution is to get those plastic window seal kits. Reduced the condensation by 90-95%. Just be sure you seal up all the little air gaps around the window before you put up the plastic.

[@james.telfer]

Increasing airflow also increases heat loss through it since you're having to warm the glass above the dew point.

[@iancormie9916]

Put the insulation layer on the outside. This warms the inside does not get cold enough to condense the humidity.

[@bethanyanderson1745]

​@@iancormie9916▪︎ how is that accomplished on the outside?

[@bethanyanderson1745]

@tweake7175 ▪︎ but traditionally heavy drapes have been installed for added warmth, right?

[@josiahbeam]

This happens in our house which was built in 2000 with aluminum windows. Thanks, Matt! Probably saved us several grand in window replacement.

[@petrawagner4946]

I love this series! Hat tip! I live in CenTex and this has been happening on all my windows, including the brand ew Pella ones. I run a dehumidifier to keep humidity at 40% RH and oin the freezing winters of the past 2 years in a row, the heat was kept at 66, maybe 67 degrees. I'm German so used to being in colder temps.

[@Wvrent]

This past summer I installed some privacy film from a company called Gila because of glare issues I was having. It also purported to have some heat retention properties and to my surprise, the one pane that has the film has no condensation or pooling. I've ordered more film to expand the testing. (These are double glazed vinyl windows)

[@bradmitchell4936]

I installed an Heat Recovery Ventilator. HRV myself for around 2500 dollars about 25 years ago now best money I’ve ever spent Absolutely no more moisture problems on door frames or windows and in door air quality is fantastic I live in Ontario Canada where it’s cold much of the year The only drawback to the system is if you have neighbors with woodstoves or fireplaces you sometimes get a faint smoke smell if the wind blows it towards your air intake Hope this helps anyone having moisture issues in their home. Cheers

[@thomassears4920]

I did the same for my attic space in the winter. Works great

[@tweake7175]

Whats your indoor humidity? I suspect its very low because you have an hrv not an erv.

[@shellderp]

@@tweake7175 yeah, in Ontario you want an ERV. Even with an ERV I run a humidifier. I'd rather have a bit of condensation than dry skin

[@bradmitchell4936]

Just to add a little more info way back before putting in the hrv the government had a incentive they would pay you back for all monies spent to add insulation new windows and air sealing of your home for energy efficiency The reason why I have an HRV is because it has a built in thermostat which causes the air intake port to close at times of very cold weather this sends heated house air threw the core to stop it from freezing up after a certain amount of time the air intake opens and resumes operating as usual I’m not familiar with ERVs if they have this cold weather feature or not It’s currently -2 here and inside humidity is 32 at present

[@tweake7175]

​@@bradmitchell4936afaik erv also have the defrost port.

[@465maltbie]

Great lesson, thanks. Charles

[@tobyhayes611]

Excellent, science based, easy to understand explanation.

[@Gbfaninnm]

Great explanation, thanks!

[@Oxblood1987]

You would be amazed what a little sun can do to warm up the frames etc. Also, curtains and even blinds can create still air that act to insulate that interior surface of the window letting it get colder. Best thing you can do is make sure you have the blinds ds open, make sure you have good air circulation and mop up the water in the morning.

[@detroithammer8869]

very useful information. thank you

[@searchingforaway8494]

Mine started doing this bad after I spray foamed the attic. It always did a small amount but nothing concerning...... NOW... Holy!!

[@Blabla-od7vt]

Great video, thanks!

[@gpowell2010]

You make. A great point on the window 2 vs 3 pane of glass

[@dlaffrey1]

Great education!!

[@AliB333]

I live in Dallas and we had those exact same GA windows. Just had a few of them replaced last year with vinyl triple pane windows. Wanting to do another batch soon.

[@timmyc7898]

Thank your for your timely video. I have been trying to figure out why I have so much condensation on my relatively new (7 yr old) windows. I know my relative humidity is way to high. I live in a tiny house (250 sq Ft ) in Michigan and have no exhaust fan. I am going to try a dehumidifier for the short term but need to add a fan. I downloaded the app you recommended and it shows that I have a dew point of about 60 deg f. Thank you!

[@martinpoulsen6564]

Get warm edge glazing with plastic/composite spacers in stead of the standard metal spacers usually used in thermal glazing. They are thermal bridges, and will transfer a lot more cold in from the outside. This goes for any window. If you really want to go after it at all costs, get windows that also have an in-built thermal break. Not sure whether they're available in the US, but certainly in Europe for passive or plus houses. This of course also means that the wall system has to be up to specs for this type of construction, or the extra cost will be of little value.

[@skiptrace4034]

The US commercial market has had that tech for a long time. Sadly most do not utilize it. Commonly marketed here as "warm edge" spacers

[@mikewest5529]

@@skiptrace4034 Window installer here. Warm edge spacers only last 15 years on the sunny side and the spacer melts and you loose the seal in the glass. Stainless spacers are the best period!

[@gregcorwin8316]

Actually the modern stainless steel spacers are very close in energy performance to the best non-metallics, and even better than some, including some of the most widely used from Europe.

[@bethanyanderson1745]

​@@gregcorwin8316▪︎ that seems to fly against conventional wisdom, doesn't it? I'd be really interested to read your sources or know which window manufacturers tote this theory. Thanks

[@gregcorwin8316]

@@bethanyanderson1745 What you refer to as conventional wisdom, I would call marketing hype because the concept of "metal vs non-metal" was developed by marketing folks and presented in a full page ad campaign that was intended to grow market share, not present accurate performance comparisons. There are several ways to compare different product's performance. You could measure conductivity of the raw materials, not taking into account how they actually perform in the actual application. You could also measure performance as installed in an actual IG unit, i.e. glass on both sides of the spacer. There is also measurement when the IG is installed in a window system. Finally, since this KZbin video discusses condensation, the systems could (should?) be compared based on their measured Condensation Resistance Factor. Since measuring thermal conductivity of the raw materials isn't directly applicable to the actual performance in a window system, this one is pretty much useless - unless you want to use it in an ad campaign, then it's very useful, if not accurate. Comparing edge temperature performance in an IG unit is a much better option as long as it's an apples to apples comparison - i.e. same glass thickness and same glass coating (if there is one). The NFRC database lists about 60 different spacer/spacer systems. Of these there about 10 or so options that comprise probably 90-95% of spacers used in North American residential window systems. In no particular order: Intercept (tin plated steel) Intercept Ultra (stainless version of Intercept) XL Edge (Cardinal IG stainless) Endur (Cardinal IG stainless) Swiggle/DuraSeal (kind of a hybrid of metal/non-metal) Duralite (warmest edge of widely used systems in North America) SuperSpacer (multiple variations (7?) with the original being the warmest) TPS (Thermoplastic spacer - primarily European, but also used by a few North American manufacturers) Technoform (also European that us used by some NA folks) And Aluminum of course Since there are about 1200 or so window companies in North America, and because there are new ones opening and old ones closing all the time, there are variations in who is using what, but for the most part, especially among the larger companies, they are consistent. As a rough estimate, in about 2018 (last industry estimate that I have seen) about 1/3 used Intercept/Ultra, 1/3 used Cardinal, and 1/3 used the remaining products listed. Since then I suspect that Cardinal is about the same, but that Intercept may be somewhat lower while the non metallics might be a bit more. Dropping the IG into a window system and measuring the CFR probably gives the best comparison of the various options by taking into account the actual window performance when using one spacer versus another. Again with the caveat that everything other than the spacer system has to be identical. Obviously that can be difficult because window systems vary even more than spacer/IG systems do. The best place to find this information is on the NFRC website. Dropping the different IG systems into a generic clad wood window, using 3mm glass with a triple silver LowE coating on surface 2, 90% argon fill and outside temp 0°F, inside temp 70°F, gives edge temperature in order of performance: Duralite - 39° Superspacer Premium - 37.7° Cardinal Endur - 36.9° Intercept Ultra - 36.2° Cardinal XL Edge - 35.9° DuraSeal - 35.1° Technoform - 33.8° Intercept - 32.5° Aluminum - 30.8°

[@trevorkolmatycki4042]

Having a high efficiency brushless DC motor for your furnace blower that you can run 24/7 at a constant, low speed circulation is excellent for reducing cold spots that can cause condensation here and there too. And it also aids with re-evaporating the condensation that does show up on the windows.

[@hoseabrawley1]

We had this issue at one of my buildings. I focused the vent to warm the window and door to prevent it from condensing on the windows and doors.

[@KJSvitko]

Glad to see practical tips and information that everyone can use. Water damages buildings.

[@hilux0094]

Hello! I’m in the northeast where temperature and humidity are a giant headache some days. I have had so many issues with condensation on windows and doors to every other surface in the house near the exterior wall. One window five feet away from another will have moisture while another won’t. Air flow is important. That’s for sure.

[@PeterHernandez-lg2eh]

Same here in Ct

[@ronlovell5374]

I'm in central Canada, I think air flow is the main reason for mine. I have heat registers under every window in my home except for the one in the stairwell, and that's the the only one that used to condensate on really cold days, until I installed a fan in the stairwell to push warm air down.

[@braedenblack6116]

Airflow is huge. Here in BC Canada we close the curtains at night in the winter to help keep the cold out. But we open them during the day so the airflow can dry the windows.

[@JohnnyMotel99]

I have found that two simple solutions for bedrooms especially, leave the door open and leave the curtains open. In my house it makes a huge difference to condensation build up.

[@robertsteich7362]

Hey Matt, a little off topic question. I see you have an iPhone and a Flir camera. Can you tell me what Flir camera and iPhone you have? I recently upgraded to the 15 Pro with USB-C instead of Lightning connector. Flir customer support isn’t sure if their USB-C camera will work… because they immediately suggest the Flir Edge Pro, which has a $400 price hike from their USB-C model. This question goes for anyone who has tested it too I suppose. Does the Flir USB-C camera work with the iPhones with USB-C? Or would the Flir Lightning with an USB-C adapter work? Or would I have to spend the money on the Flir Edge Pro, which works wirelessly.

[@erikthie2253]

I live in Calgary Alberta and in Jan and Feb we get to -40C. We definitely have humidity and condesation issues with our windows and we have pella triple pane windows. The issues you spoke of are absolutely true but i will add that if you have a bedroom you usually have a blackout blind to control the light at night. This will create a lot of condensation on those windows. The builder had the same explanation like turning on fans and decreasing the humidity which i found untrue. To have your house at a lower humity than 40% is unbearable.

[@Bradimus1]

We replaced three windows on our house with Pella because of condensation issues. We were just replacing the problem windows and wanted to keep matching vinyl. The Pella were the highest rated I could find for vinyl. It's helped a lot.

[@howardsmith5474]

Wow turned a discussion about condensation political, impressive input into the conversation 👎

[@kooale]

He is a rather perfect ruler for the measure of truth and dishonesty.@@howardsmith5474

[@kooale]

Many thanks, that makes your statement crystal clear for this potential new window buyer. @@DuffyGabi

[@happyotto6436]

To avoid condensation 1) keep air humidity about 40% , not more during the cold season 2) the window frame and glass temperature (especially corners) must be higher than dew point temperature, to do so in some old houses the surface below windows was at 45 degrees to the floor, so the heat from radiator , which was located right below every window can easily heat up the windows. This days one can easily integrate electric heating cable of plastic heating water pipes in to the windows boards

[@bethanyanderson1745]

@happyotto6436 ▪︎ weren't these the old boil-fed radiators? If yes, they were so large they practically covered the entire wall space below a window. I would think some enterprising individual or company has already tried/studied/evaluated adding a wall-intregated heat source below a window. The trick is finding the info.

[@jerryrobinson7856]

‼️ Damn cold Chicago here. We commonly have in the furnace humidifier’s. We set it to 40%. But, under 25 degrees F. we have to lower it to 35%. One thing people mis is windows on the north (non sun) side of the house freeze more. When we do get ice build up, the south side melts much faster, often by mid day. I have tried running a fan on these north windows to no avail - a waste of time. It is a maintenance issue where drip surfaces will cause bacterial build ups eating the paint in the painted wood frames and moisture causing surface mold, like behind drapes and blind sheers where the air movement is low and sun or bathroom heat cause bacterial build up. I spray it with hydrogen peroxide and let it sit. Go back with gloves, mask and apply more hydrogen peroxide and wipe with paper towels into a zip lock bag to toss. Because bacterium needs heat, windows on the south side get it the worst. We have a 300cfm bathroom fan on a timer, so even with that, it’s just unavoidable with sheers typical in a bathroom.

[@mine_addict]

I live in northern quebec in canada and we have -60f often during winter we have to use plastic shrink warp on all our windows to be able to keep them ice free. Triple pane window

[@Cspacecat]

I built 6 layers of clear plastic and vinyl plastic framed inserts for all my windows. They feel warmer than the gypsum board walls. Condensation is due to heat radiating out through your external structure in the winter. Insulate your house.

[@birdlegs846]

I live in Wisconsin and I hate how dry the house gets in the winter so I run a humidifier. I keep the thermastat temp at 69-70 degrees and humididy set at 40% on my humidifier. When it gets down to like -5F or colder I get a little condensation on very bottom of my triple pain windows, all I do when it gets that cold is just turn my humidifier down to 30% and then the condensation disapears.

[@leagarner3675]

Same. My humidifier is attached to my furnace but it's the same concept since it has its own controls.

[@zachlafond2652]

Should have done this in the early morning before the sun came up. Also what direction are these windows facing. My south facing windows don't get as much condensation as the north/west facing panes. I built frames that friction fit into several of my north facing double hungs.

[@TJ-22]

Great content, Matt. The only windows that condensate in my house, happen to be north facing windows. Is it common to have windows on the north side of the house more susceptible to condensation, or is that just coincidence?

[@holtrussell]

Hi Matt, great analysis! It looks like based on your FLIR image that the lower right side of the window in question was significantly colder than the lower left side of your window. Does the difference in performance indicate a failing window, a broken window or improperly manufactured window or an issue with installation? Seems odd that only one area of the window would be performing so poorly as compared to the other areas (unless other environmental aspects are in play)? Very interesting at a minimum! Thanks!

[@dondumitru7093]

Note that where the sun shines can have a significant effect on temperature, so if one side is shaded and the other has been in the sun, you can see a temperature difference.

[@readyplayer2]

It’s also important to keep in mind that the color scale is relative to the temperatures of what is currently visible in the frame of the FLIR device. So what may look like a massive cold (dark purple or black) or hot spot (bright orange or white) may only reflect a small deviation in temperature of a couple of degrees.

[@holtrussell]

Interesting. Maybe a result then of too tight temperature variation inside the window of the FLIR. Not sure what the difference of material thermal expansion rates of glass and composite, but seems possible that asymmetrical heating or cooling could cause the window to distort or even fatigue fracture over years of cycling.

[@shellderp]

Flir does not work so well on shiny objects btw

[@bethanyanderson1745]

​​@@readyplayer2▪︎ @shellderp ▪︎ good to know

[@alberthartl8885]

Thank you for making it clear that window condensation is all about dew point and the surface temperature of the window. Lower U values will translate to warmer surface temperature. Heat exchangers, bath fans, register location, curtains etc etc all influence the relative humidity next to the glass. It is just physics. Windows are expensive so there is the temptation to save up front costs with code minimum units and give no thought to future HVAC cost. U .20 windows are readily available and will have a short payback period. Windows up to U .10 are available from several specialty manufacturers. Bottom line, buy the best windows you can afford.

[@trevorkolmatycki4042]

“Humidity control does not equal condensation control” I have to disagree with this statement as worded. If what you actually mean is humidity control is no substitute for better insulated windows and better vapour barrier… then I agree. Up here in northern Alberta winters are cold and dry… and condensation on double pane PVC frame windows is “controlled” in my 2007 relatively loose house with a whole home steam humidifier modulated by a humidistat with an outdoor temperature sensor. The humdistat reduces humidity setpoint when the outdoor temperature gets colder. With this system I can vary how much condensation shows up on the windows with ease.

[@buildshow]

Yes. Excellent modifier. Agree

[@CMCraftsman]

Lil Jon knew all about condensation on windows back when he made that song. How’d it go? “The window and the wall! Sweat drip down and fall!”

[@holymackerel]

What direction are all the windows facing? How much air is moving around the window? There's more factors that go into condensation.

[@T_157-40]

Last night (20 degrees F), I left my wet gym towel inside my SUV. At 5 am when I started engine-defroster, condensation on windshield required scraping of ice inside & out plus side windows where mirrors are. On a wet towell!!!!

[@Oh22Yeah]

Also depends on the direction the window is facing as well. Typically your south-facing windows won’t have this issue as much because of higher sun exposure. Maybe consider having higher quality windows on the north side where the temperatures will be a little lower. Also just a comment on people suggesting putting registers under the windows - this is great for solving the condensation issue, however from an energy efficiency perspective, you’re losing more of that heat through the inefficient window assembly than if you were to place that register elsewhere.

[@jebimasta4604]

curious, what is a register? google is not my friend

[@Oh22Yeah]

@@jebimasta4604 Diffuser I guess would be another name? Or vent? The place where hot air is supplied to a room - in Canada usually on the floor under a window in single detached homes.

[@bethanyanderson1745]

@Oh22Yeah ▪︎ always someone who’s the buzzkill (lol)

[@Tina-tz2ud]

Any suggestions for someone like myself living in an apartment? I have a lot of condensation on brand new windows just put in, my humidity is around 47% , my apartment is heated with electricity not a gas furnace.

[@brandjayfab]

This is why in HVAC it is recommended to place your duct vents nearest your windows and doors to focus conditioned air in those areas to promote airflow and heating.

[@rdoubled1384]

Where can I find "bomber" glass?

[@johnnyv5995]

When measuring the dew point, is the outside temperature now a factor?? I see you only entered indoor temp & humidity- thanks.

[@gregcorwin8316]

No, dew point is independent of temperature

[@brokenwrench404]

We need the TV show “this old house” back with Matt hosting

[@nholt]

It’s still on PBS. And the current host is doing good.

[@rdizzleoriginal]

I just run the dehumidifier all year to keep the internal about 40% More comfortable all year too

[@TofuInc]

I replace all my windows and if it gets below 20° we still get some condensation on the glass at the base of the windows. Still much better than the old single pane aluminum windows we replaced. Any extended periods below 20° and we would get ice all around the frames at the base of the windows.

[@RandomVids519]

I have a dug out basement (all dirt floor) one window close to furance not condinsating the other one away is im guessing its the basement not my new 5 week old window lol??

[@nickadams9841]

We a have a new eco home in Alberta with triple glazing PVC windows through out. We maintain 38% humidity through our HRV system, and any outside temp below minus -10c we get window condensation especially if the windows are covered with curtains or blinds. Just unavoidable even with high quality windows given the right environmental conditions. Having constant unrestricted internal heated airflow over the windows is the only way to reduce the amount of condensation......

[@lilbeesting]

Im in N. Texas, my home was built 2005. EVERY SINGLE ONE does that and i have a load of water puddles and it puddles A LOT, I MEAN ALOT!! Can you recommend a window company here in texas that has good windows without having to sell your kidneys?

[@markjordan3312]

Do those have argon gas?

[@DrMJJr]

FENSTUR ARE AWESOME WOOD WINDOWS!!!!! 🔥🔥🔥

[@mattshinay]

This happens so frequently that I’m starting to see mold. Can you recommend a remediation strategy to stop mold growth? I’m in New England and this happens every morning in the winter months!

[@Evan-bc6nb]

Moldex or Clorox Clean Up worked for my winter window mold issues. Just be sure to go back every month and check them.

[@engineer1692]

Lower you're humidity in the house. Get more airflow over the window. Put up a clear plastic winter cover over the inside of the window.

[@james.telfer]

Neat bleach kills any mold, just be mindful of any effect on the materials or paint in that area.

[@kennethhughley1611]

I've seen this many times. Sunny summer days. Air-conditioning blowing up the window.

[@MrJramirex]

Jeld-Wen windows if anyone is wondering who made the trash double pane windows.

[@leighann49]

Matt you should be doing the National Continuing Education Program. Make them stop doing this ripoff sh%& there doing now.

[@ecospider5]

If you don’t want to replace your brand new windows then a $10 window insulation kit works great. You just need to make sure the air trapped between the film and the window is really dry.

[@JaredHoutsma]

This is what we ended up having to do. We have north facing windows in the Minnesota, the windows never heat up in the winter. I thought the plastic film was for older windows but it was the only solution that kept moisture off the windows in the winter

[@ecospider5]

Good to know it works in that climate.

[@AsHellBored]

put rain-x on the inside of your windows. If there is no nucleation sites it should help.

[@ryanpernia1426]

Window coverings seems to have a marked effect on condensation. i notice that my window coverings on my new build do have some thermal value thus surface temp of frame/glass remain low relative to true inside temp if fully covered. all windows not covered never have condensation because its closer to inside air temp. interesting phenomenon but I guess its all explained by science!

[@tamil1001]

Does Europe or Canada have higher code requirements for window performance compared to colder climate zones in the US. If yes, why are our standards low? Simply cost?

[@virtueofhate1778]

I don't know about the code requirments, but here in Finland the basic window design is very different and condensation is not an issue and has not been an issue for almost half a century. No matter what the humidity in the room is or how cold it is outside our windows stay dry. In my opinion the North-American window design is just bad for the Northern climate no matter how many panes it has or what material it is.

[@PeterPutz82]

Interesting. Each time I see a video from Russia in poorer areas, they have an outer window and an inner window. I wonder how effective this would be? I assume the outer window is freezing but not exposed to warm inside air and the inner window would be just warm enough to not condense?

[@virtueofhate1778]

It is very effective. We used to have the same window design with outer and inner single pane windows with a big gab between them in the older days here in Finland. Now with the evolution of these windows we have single pane outer window (aluminum) and triple pane inner window (wooden) in a ~8 inch wide wooden frame and there is zero problems with condensation. Russia on the other hand is nowadays mostly adopted the American style window (most often plastic) design because they are cheaper.

[@gregcorwin8316]

Dew point, technically saturation vapor density, is 100% relative humidity. Dew point is based entirely on the level of moisture in the air and is totally independent of temperature. Said again, air temperature (inside or outside) has NO effect on the dew point temperature. As shown in the video the dew point temperature can be determined using air temperature and relative humidity. That calculation works because relative humidity is a percentage of the dew point (or 100% Rh) at a specific temperature. Since relative humidity is a percentage of total moisture at a specific temperature, Rh can be changed by adjusting temperature. Raise the air temperature and Rh goes down. Lower the air temperature and Rh goes up. But raising and lowering air temperature does nothing to change the dew point. Because of this, using Rh when discussing window condensation can be misleading. As an example, a room with 6.25 grams moisture per cubic meter of air will have a dew point of 3.33°C (38°F). If room air temperature is 18.33°C (65°F), then Rh will be 40%. Raising room air temperature to 23.9°C (75°F) will lower the Rh to 29%, but dew point remains the same at 3.33°C (38°F). While you "feel" differences in Rh, and it is important in many of the building materials used in your home, it's not necessary an indicator if you will have window condensation. If glass temperature is above dew point temperature - no condensation, if glass temperature is below the dew point temperature - condensation. Takeaway from the video -- "humidity control ≠ condensation control" is correct IF it's amended to read "relative humidity control ≠ condensation control", however humidity, when considered "as total moisture in the air", is absolutely the primary consideration when dealing with window condensation. There are two ways to control interior condensation, first raise the glass temperature to a level above the dew point; second, remove moisture from the air to lower the dew point to a level below the glass temperature of the windows.

[@grand04gt]

It always seems to start on the lower corners so i am curious if the outdoor airflow collects in those spots (one side is always worst) and then you also have how the window is sealed as we all know anywhere you put a joint it is super easy to have a minute amount of space for air to flow thru. My bedroom window is brutal in winter (i actually scrape the ice insidesometimes) but the best to stop the window condensation is the cheap plastic wrap as when i do it there is never even 1 drop on that window

[@bfelb]

Heat rises in a room, the top corners are warmer than the bottom.

[@bfelb]

Install your windows at least half way into the wall, and the window frame should be at least 2.5in thick, and you wouldn't have this problem.

[@davehaggerty3405]

In Ohio fogged windows are an indication of a crack in the furnaces heat exchanger or a blocked chimney. Putting carbon monoxide into the living space. This is completely fogged windows. Not just a little condensation in the corners. And with the locally typical double pane, vinyl framed windows. So if a home suddenly starts getting foggy windows look there first. It could be anything from a bad furnace to a bird’s nest in the flue pipe. And it needs fixed before you go to bed that night.

[@somethingkindawonderful3034]

Taking screens off in the winter makes the condensation drop dramatically

[@baxt1412]

Why would that change it?

[@somethingkindawonderful3034]

@baxt1412 no idea air flow by the windows ? .. great question but it's really night and day

[@garyhiland6013]

Folks, please just go straight to the NFRC label and observe the Condensation Rating number. If it doesn't have the number (it is optional as is air infiltration rates) and the seller can't provide the info, don't buy that product. So much gnashing of teeth here. Oh warm edge...plastic spacer -- go to the label and read the spec. Oh does this brand....even a that brand will -- what is the Condensation Rating number? Wood, aluminum, clad, vinyl -- what does the label say? That points you 50% of the way to freedom from condensation woes. Keeping humidity down to 30% will take you the rest of the way home. Well okay getting warm air to the surface by removing screens and raising blinds is a smart thing to do. So what numbers should we look for? For double pane windows, high 50s to low 60s is good. The sample shown in the video of 62 is great for double pane. Btw, the top line specs of the two windows in the image at 10:09 are identical: double pane, Low E and argon filled. But the one on the left is el cheapo and the one on the right is top drawer. For triple pane look to be in the mid 70s or better. Then buy the best you can afford and your climate demands.

[@youdontknowme5969]

You had me at "dewpoint" 😊

[@robertfitzgerald8243]

Matt the operator window had mpisture no function window didnt u know why that is

[@somethingkindawonderful3034]

Matt I have noticed on my own windows .. openers condensate more and fixed windows don't as much or at all . Your condensation was on an opener. . And not on your fixed.

[@raketenolli]

Some of your shots look like air is leaking in on the corners? My experience is that windows common in the US don't shut as tightly as European/German designs. Triple glazing doesn't help if air can find its way around it.

[@jamescohen5200]

Old school storm window will fix this

[@andreassetterlind]

You forgot to mention condensation that occur on the outside of a well insulated window when its outside is colder than the due point

[@gregcorwin8316]

Curiously, exterior condensation can occur even when the air temperature is above the dew point since the glass can be colder than the air temperature due to glass radiation to open sky (actually all the way to space)

[@NimbleBard48]

"Code approved" means that it's the MINIMUM you can get away with. People should already have an inkling that they might want to go higher than that.

[@GenZyannd]

that's pretty sad that the solution is to install expensive windows. How about using mechanicals strategically to warm up the glass, or use window treatments probably to avoid keeping the glass cold.

[@kirkellis4329]

I'm pretty sure I read an HVAC recommendation years ago about floor HVAC registers being better than wall registers and to place them in front of windows and doors. Easy enough with basement or crawlspace or upper floors, but not exactly a retrofit for a slab foundation. Yet another reason I might build the only house in the neighborhood not on a slab -- ease of mechanicals access from underneath.

[@fjsantana12]

He said 72 is a little warm lmao

[@dustup2249]

Not a single word about gas ranges and heaters in the home causing condensation. Natural gas is 80% water vapor...

[@leagarner3675]

I hope your house isn't full of natural gas.

[@somethingkindawonderful3034]

Bring back the wood stoves ..

[@leagarner3675]

@@somethingkindawonderful3034 We heated with wood for a few years and yes, it sucks all of the moisture out of the air.

[@fochdischitt3561]

Bust of the micro climate by pointed duct work at windows.

[@jonfromsyracuse]

lol hey my dog's name is Ben. He's also a Lab.

[@user-dk2xz9yj2w]

Doesn't these corner condensations in relatively modern windows have to do with not welded corners? Has anyone tested this with welded corners on like pvc windows with welded corners?

[@mylesburley7251]

What a beautifully done kzbin.infoUgkxYGamVaHfdHiPlAQaLa7zkwR02OKpGYDU ! The instructions and the photographs are brilliant. It is thorough and genuinely informative. Ryan got another winner! No one does it better!

[@kirkellis4329]

Does anyone else find it ironic that many building codes REQUIRE a huge fraction of wall space be windows, not just for egress in bedrooms but for "natural light" and as an "energy conservation measure" to reduce electric lighting, when windows create so many problems ? California codes require a minimum window glass area of 8% of floor space for any habitable room other than closets and bathrooms. Yet, windows reduce whole-wall insulation value and therefor energy conservation, invite water damage from flashing leaks, almost guarantee condensation problems like this, and force you to have windows in rooms like home theaters that SHOULD NOT have any external light. How moronic to have to spend money on windows with all their potential problems in rooms that will then require more money spent on light-tight window treatments that are always closed. 90% of my windows are always covered -- not all of us want to look out at our neighbors or them looking in at us -- so those windows and window treatments are just wasted money.

[@battlebotts]

I bet the gas I between the pains of gas was gone. That’s a big culprit on new style windows

[@georgejetson4378]

I know my comment is completely off topic and more of a rant but after watching this and other YT videos, I’m just curious if anyone else has observed the growing number and frequency of ad placements. I can remember not too long ago when most YT videos would run practically ad free. Then, they started with a few ads that you could easily skip over. Fast forward and now it’s two 15 sec ads back to back placed throughout. This medium is quickly going the way of network TV. It saddens me to realize that it’s all about the money and altruism is dead.

[@patrickgeorge141]

Code is a minimum standard not what a great builder should strive for.

[@designbuild7128]

to stop condensation, crack the window ;) That's what happens when a house doesn't breathe [e.g. leak all over].

[@virtueofhate1778]

Not true. Condensation happens when the windows are not suitable for the climate.

[@designbuild7128]

@@virtueofhate1778 thanks for the correction of my joke. Duly noted.

[@virtueofhate1778]

@@designbuild7128 Hah, with new eyes, I see it now. Good one. 👍

[@guerinwoodgate]

No mention of testing for leaking or missing argon gas which could be a manufacturing defect. If you want to be scientific, why not measure the temperature of the glass outside and inside to determine if your new windows are properly insulated between the panes of glass? Definitely do not want to use a thermal camera to measure the temperature of the glass.

[@Pallidus_Rider]

Condensation is your window telling you it needs to be cleaned 😅

[@jamesp2391]

Haha! I think the high here today was 28

[@user-oc1wl5nb3m]

Why doesn't this happen to European windows?None of my double glaze or triple glaze European windows have ever done this.

[@gregcorwin8316]

In the right conditions it absolutely will happen on european windows, physics is physics

[@virtueofhate1778]

​@@gregcorwin8316 What are those "right conditions?" I live in Finland and I have 20 years old windows that have never had a drop of condensation on them no matter what the conditions are. Further more, I have never seen any window with condensation unless the window has been damaged somehow. You just happend to have very bad basic design on your windows and you keep on hanging on on that bad design even if there have been better windows for a half a century.

[@gregcorwin8316]

@@virtueofhate1778 The "right conditions" are when the indoor humidity is high enough and the outside temperature low enough that the temperature of the glass is below the dew point temperature of the air in the home adjacent to the windows. One good way to see moisture on glass is to block the windows with curtains (or blankets, or whatever) when it's very cold outside. Where I live it gets very cold in winter, actually a bit colder on average than central Finland, and I agree that too many people here are far more concerned about what a window looks like than how it performs, which results in inadequate window performance. What too many people think is good to even great performance is actually barely, or less than, adequate. Another problem is that despite bitching by American consumers, energy here is still very inexpensive by the standard of almost everywhere else in the world, so too many people worry about today and not tomorrow when making a window purchase. Also where the majority of people live in the US, high performance windows are simply not a consideration because temperatures are mild and the additional expense of high performance products isn't easily justified. Form over function rules. In many areas, a very simple window system with a good LowE coating on the glass to block solar gain is more than adequate for their environment. I installed tilt/turns in my house 18 years ago. My windows were built in Canada using extrusions and hardware imported from Germany and a glass package from USA. At 18 years old these windows still perform like the day they were installed and have energy performance numbers equal to or better than most windows coming out of Europe, but when it's -20C here (or colder), and I take a shower, the windows in the bathrooms (one in the shower), will develop some moisture along the bottom edge of the glass because the high humidity in the bathroom does result in a very high dew point above the temperature of the glass. High performance tilt/turns are readily available in North America. Some of the larger window companies have offered them for decades, but no one was asking about them, or buying them, so they are either a niche product or the company simply stopped offering them. Currently the best place to find tilt/turns is from a smaller, usually regional, manufacturer who specializes in the product. Some of these small manufacturers can be traced back to European headquarters or origins, and some are totally home-grown.

[@thelouiebrand]

I’m really surprised at the results of your home. It’s over built in comparison to say even a 20 year old home.

[@carguy1312]

So, I need to replace all of my windows with Triple pane. Crap. I can tell you a $1k Pella has a TON of moisture on a 28* day.

[@benniepatton6544]

Love your show, but not your intro of "let's get going". Cheesy to me when you really emphasize it.

[@squidlips6661]

Your windows need to be heated adequalty my friend. If the window is not well heated dirtectly best by the bottom not by the ceiling you will have no condensation. I live in Qubec where we get -40 deg. celcius temps in the winter and crappy condos all condensate but The museen I designed, did all the technical detailling of all juntions etc. and did the site supersivion in Qubec has large curtain walls in a 50% humidity environment and 0 condensation in the museum and this is the same in residential, schools and hospitals I have designed and drawn all of the technical details amf have been built adequatly. The cold surface of your windows needs to be heated and you need to start building using the Perfect wall method and stop wasting money insulated sutd cavitys wood or steel studs (worst). Perfect wall is the only wall in the world tha works. Your thermal cam shows all your wasted energy at the stud locations, etc. You are still a very good builder and builder that knows his sh....t. Keep up the good work, many you will convert crappy contractors to build better and waste less energy. Litezone glass is absolutly amaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaazing.

[@BurtmannNautique]

Talks to much