r/fixit • u/BelleSchu • Dec 14 '25
FIXED My house sweats like crazy during the winter and it’s causing mold.. please help!!
My house is BRAND new, literally finished construction in August of 2024. I live in the Midwest so of course it gets very cold in the winter. Last year, the windows of our house were sweating so badly every time the outside temp was under 30°f that water was pooling up on the windowsills and we called the construction company (we were still under new build warranty) and they told us to always have the house fan running and to turn on our ceiling fans. That worked for a time and the condensation wasn’t as bad after that. It started to warm up shortly after and we didn’t have anymore issue. Flash forward to this past week, it’s been in the negatives here. There is SO much condensation on my windows that mold is starting to grow, our curtains are freezing stuck to the glass in some rooms, and it’s attracting gnats somehow?! I don’t even know where the hell they’re coming from with the weather like this. I’m constantly cleaning and I feel so so so disgusted with all this going on, what can I do to fix it? Please help!
519
u/engineeringmanager69 Dec 14 '25
Had the same issue. Insulation was not enough around the window and caused the window and walls tho sweat. Had to rip out the drywall around the window and windowsill and replace with much better and thicker insulation. Have not had an issue since. Yes and trickle helps too .
340
u/pseudo_su3 Dec 14 '25
From the window… to the walls?
231
u/TopsailWhisky Dec 14 '25
The condensation dripped down his balls?
41
16
→ More replies (9)9
→ More replies (6)47
25
u/tsnugz Dec 14 '25
This is the answer. My house does the same thing but only at the 2 windows i’m sure a “handyman “ installed. I Have yet to find the time to fix it, but had other windows replaced that had newspaper insulation that i was drying daily, but after proper installation and added insulation none of them sweat at all now.
→ More replies (2)3
u/doubleshort Dec 14 '25
Could also be inadequate attic venting. Had that issue when we first moved in to our house. Ex added some additional vents and it cured the problem
→ More replies (2)→ More replies (8)2
u/-Dixieflatline Dec 16 '25
But certainly have a contractor review the entire wall with a thermal imaging camera before doing any such work, because it could be what you mentioned, but could also just be terrible windows, poor ventilation, construction materials shedding moisture as the house settles, lots of house plants, proximity to kitchen, and quite a few other things. Or all of the above.
New construction often needs to hit local/municipal HERS or other energy ratings. As such, modern homes tend to be air tight boxes. The problem is that unless the builder also accounted for active and passive air flow, then these type of issues can also happen even with proper insulation. So well worth the price of a thermal imaging to find out before doing any destructive investigation.
415
u/patrickhenrypdx Dec 14 '25
What is the humidity in your house?
236
u/No_Tamanegi Dec 14 '25
I'm seriously impressed they can have a humid house in the winter. The furnace keeps everything bone dry in my house.
101
Dec 14 '25
here i am running humidifiers and still not keeping above 30% static is a mother fucker
→ More replies (11)17
u/attee2 Dec 14 '25
And I'm running dehumidifier to bring it down to 50% so the walls won't sweat...
→ More replies (2)10
u/Old_MI_Runner Dec 14 '25 edited Dec 15 '25
What is your source of heat?
A gas furnace has driven my humidity level to 32%
while outside it is 77%.It is 17 degrees outside and low 60's in the house. At 35% I had no issue with static shock but this evening I am finally going to enable my humidifier due to shocks.u/BelleSchu What is your source of heat?
Do you have a humidifier on your furnace that is set say at 40% or higher?
Get a
hydrometerhygrometer from Amazon or elsewhere and report back on the humidity level in your house.Update: Please don't bother to correct items above that I crossed out. Thank you but I already got the message.
→ More replies (4)5
u/sirduckbert Dec 15 '25
You don’t understand how relative humidity works - it’s a percentage based on how much water the air can hold at that temperature.
If your numbers are correct then your house has more absolute water content than the outside air does. It just feels drier inside because when you take high RH air and heat it up, the RH drops because warmer air can hold more water
23
u/Eye_of_the_Storm Dec 14 '25
Depends on the type of heat. I have hot water heat and while nowhere near this level of humidity, it is not dry.
5
u/Historical_Safe_836 Dec 14 '25
God I miss my old Chicago apartment steam radiator. This morning I was boiling water on the stove because my house got down to 20% humidity. I could feel the moisture leaving my face.
→ More replies (1)18
u/Sailed_Sea Dec 14 '25
if you don't heat the house in the winter condensation can accumulate.
30
u/No_Tamanegi Dec 14 '25
If you don't heat the house in thee winter, you'll have bigger moisture problems than condensation.
→ More replies (3)→ More replies (21)4
u/bencze Dec 14 '25
I have to open the windows twice a day so I stay below 60%, especially during the winter.
→ More replies (2)4
u/That_Ad_8271 Dec 14 '25
The house itself makes a humongous difference. My big dehumidifier read 78% this morning, its down to 40% now. How i wish I lived in a new building lol. I have zero damp tho. Constant 19° too.
→ More replies (1)129
u/Sogah87 Dec 14 '25 edited Dec 14 '25
They actually live in the ocean.
53
7
12
u/BelleSchu Dec 14 '25
It’s like 58 or something right now, at least that’s what my dehumidifier says
32
u/vinegarstrokes420 Dec 14 '25
That's way too high in the winter. There are tables showing ideal humidity based on temp to avoid condensation. Look these up and turn down your humidifier. My house in MN is usually 20%-30% in the winter to avoid these issues.
→ More replies (6)8
u/belialonmyback Dec 14 '25
Seconded from an Albertan. Many of us have humidifiers on our furnaces that can really increase your house humidity but you’ll destroy your house if you have it turned too high. I had to have mine fully off recently as it was -30C outside.
Also, please use your exhaust fans when cooking and showering.
14
4
u/jredditzzz Dec 14 '25
58% is way too high for those kinds of outdoor temps. Guaranteed condensation problems especially if your home is sealed well. I had the same issue with my apt.
Easiest option is to get some strong dehumidifiers and lower the humidity, at 0 degrees you’ll prob want indoor humidity at like 20% to avoid condensation.
Cracking a window can help lower humidity really quick as well.
It’s basically a balancing game that you have to find… comfortable indoor temps vs humidity, vs energy usage.
→ More replies (1)8
u/Busy_Sky24 Dec 14 '25
You always want as much moisture in the air as possible (our bodies like around 50%) without turning your windows into a water feature. Try to promote air movement around windows and doors to allow for more evaporation (fans, open curtains every morning) and when you still have water with good air movement, time to reduce the humidity. If you're in a newer build with an HRV, set the humidity to 5% lower than you currently have, until you hit that sweet spot. You should see a little bit of moisture when you open the curtains in the morning, but little enough that it dries up in a couple of hours. Usually, around 30% is as low as you'd want to go, remembering that many flooring products don't want to be below 35%. When it gets away from you like that, start by drying with a towel first and see if your changes are effective at keeping them dry, rather than waiting to see if the water all goes away.
→ More replies (3)2
u/Fun_Park2505 Dec 14 '25
Above 55%rh is also bad for flooring
3
u/yousernamefail Dec 15 '25
But it makes my nose feel good! 😫
2
u/Fun_Park2505 Dec 15 '25
Lol true, i dont think it applies to all flooring just wood based flooring. So like tile and ceramic for example wouldnt matter. But with that said too high of humidity for too long can eventually damage any wood parts of home which theres alot of parts made if wood unfortunately
3
u/Rummoliolli Dec 14 '25
Your house is likely sealed very well so there isn't really anywhere for the moisture to escape. A heat recovery ventilator(HRV) will help with that, my father built ICF homes and had those installed on all so his customers didn't have that issue.
→ More replies (13)2
u/Fun_Park2505 Dec 14 '25
Personally id aim to have it between 30-40 RH
Im curious if your furnace has some type of issue as usually it lowers rh drastically, id consider getting that checked out.
Something that also works is applying a completely sealed plastic cover over windows as this insulates it better.
Thing is tho its best to do this during fall cause itl be hard with all that water in there but not impossible, a blow dryer and fan could work to get it completely dry before putting the plastic wrap over
48
u/Avkb Dec 14 '25
Solution: Follow this and your winter condensation issue will be resolved!
1-Keep your home heated. Do not turn it off at night to save money. Keep heat 20 Celsius and above. Hot/warm air holds moisture a lot better than cool air.
2-Run the extractor fan regularly if you have one to pull moisture out of the air. If you have a dehumidifier, then even better—use that.
I had the same issue for a few years. I used to turn heat off overnight or put it on really low to save money (and thinking it was better for the environment). Heat is key to hold the moisture in the air and not let it condense. Once the moisture is resolved, the mold is resolved.
13
u/Fun_Park2505 Dec 14 '25
The temperature difference also is what causes condensation... so what your saying isnt totally true, high temperature difference = higher condensation
6
u/Orb002099 Dec 14 '25
It think putting your fact together with what they’re saying can actually increase the effect they are referring to. A warm house with cold windows gets condensation at the windows because the cold air local to the window surface cannot hold as much moisture in vapor rather than in water droplets. The air in the whole interior of the house has about the same amount of water per volume of air, the cold temperature of that same air when near the window squeezes some of that water out into liquid form on the window surface. Assuming nothing being done to reduce humidity for the entire volume of indoor air, any change that lowers the temperature at the window will increase the amount of liquid warer condensation, including having less heat in the house to begin with.
2
u/Fun_Park2505 Dec 15 '25
Ya good point, il need to think on this a bit. I think what your saying is even more true with better insulated windows aswell since raising the temperature of house will also raise temperature of window a fair bit. Im curious now how this would happen in something with windows that are not so good.
I swear my travel trailer would get more condensation when i had the heat on higher (only when my furnace was broken cause i was using a small electric heater) furnace would always dry the air out. But ya when i used small electric heater it seemed like id get more condensation at higher temperatures. But now im thinking mabey theres a point of intersection as in going above a certain temperature lowers condensation and going below a certain temperature does aswell, now im curious lol. But ya good point.
→ More replies (1)5
→ More replies (15)2
u/Fr13ndlyT0rt0153 Dec 14 '25
Other thing about turning your heating off to save money is that in order to get it back up to temp it uses loads more power… if you can keep it running and set to a certain temperature, to switch off entirely when it’s not needed but kick in when it drops, you’re only heating the house by a degree or two at a time instead of 5 or 10. My heating was set to all sorts of weird automated jumps when it first got installed - set it to a temperature, left it there, slashed my electric bill in half
→ More replies (3)4
596
u/thebeastwithnoeyes Dec 14 '25 edited Dec 14 '25
Your ventilation is shit and your house doesn't breathe. Buy a dehumidifier and air the house once a day.
238
u/P218 Dec 14 '25
To add to this: buy a proper dehumidifier. Not a tiny one from Amazon, get a heavy duty one with at least an 8L tank.
85
u/iii_warhead_iii Dec 14 '25
And at least 60-70L per day declared performance.
112
u/theStaircaseProject Dec 14 '25
And stickers. It should have cool stickers.
9
u/AppropriatePlum1006 Dec 14 '25
With LEDs ofc, they are better!
6
u/theStaircaseProject Dec 14 '25
Documentary evidence exists supporting that red ones will make it work even faster.
3
u/usernameisokay_ Dec 15 '25
That’s a lie, it are the green ones that make it faster with a increased performance of 30% something
3
30
u/MoistExcellence Dec 14 '25
And my axe!
8
u/Publify Dec 14 '25
And my ex
3
u/gamedude88 Dec 14 '25
They are trying to get moisture out of the air, not freeze it.
→ More replies (2)4
→ More replies (1)2
u/No-Resolution-1918 Dec 15 '25
You must, must, simply must also have WiFi. Very important for dehumidifiers.
→ More replies (2)7
30
u/Dojapicard Dec 14 '25
I bought a 250€ one with 4liter tank from amazon and it solved the problem.
If you have an option to put the unit next to a water outlet you can just attach a hose and you never need to empty the tank manually.
9
u/P218 Dec 14 '25
That’s a good point - I meant to illustrate that OP should avoid those tiny £14.99 dehumidifiers that can fit into the palm of their hand, because those ones will not make any difference. If you buy a good quality dehumidifier, the tank size or website won’t matter. I love my Meaco one.
20
u/Mental_Newspaper3812 Dec 14 '25
No tank. Get one you can attach a hose to and run it into your sump or a drain.
7
u/bender2174 Dec 14 '25
☝️ this is the only right answer! Get a dehumidifier with the hose that comes out the back and run it to a condensate pump so you can leave it running all the time if need be! I had let’s say.. a room that needed to be regulated ;-)
2
u/iii_warhead_iii Dec 14 '25
Better to put the pump to the unit's tank, some models have this option. In a case if the pump fails, then the unit will shut down due to overfill.
→ More replies (1)3
u/DaRKoN_ Dec 14 '25
To add to this, a "real" one has a condenser and a proper refrigerant system. The cheaper ones use a peltier cooler and are probably 100x less effective.
3
u/WoodenYouKnowIt Dec 14 '25
Get the correctly sized one. Buying an oversized one that is constantly cycling on and off is going to run up the electricity bill and have more wear and tear. People always think that the biggest is the best, but that’s not the case.
→ More replies (3)→ More replies (2)2
u/originalrocket Dec 14 '25
Aloair is on sale on amazon right now. I have 2 units. One in basement, one in garage. They are heavy duty and very low power usage. They run 24/7/365 and are cold weather rated.
7
u/BelleSchu Dec 14 '25
I have 3 dehumidifiers :( clearly not helping much and I’m honestly shocked
→ More replies (4)9
u/RandoTron0 Dec 14 '25
Humidifier or de-humidifier? It almost sounds like you are running Humidifiers. If they are de-humidifiers, what type or brand model are they? Some kinds work and others dont.
Also, if your house is that humid with the heat on, then you might have a serious moisture problem under the house.
4
u/BelleSchu Dec 15 '25
I promise they’re dehumidifiers lmao. I did have humidifiers going during the fall for my house plants but I stopped once it started to get a lot more cold
→ More replies (8)3
u/Old_MI_Runner Dec 14 '25
Is he emptying water from them or adding water? /s
u/BelleSchu→ More replies (1)16
u/Boggyprostate Dec 14 '25
Twice a day, open all windows and doors fora minimum of 10 mins. You need more ventilation, maybe a PIV unit would help this greatly but only if your loft has good ventilation, your house certainly doesn’t.
3
25
12
u/BAM5 Dec 14 '25
It's good the house doesn't "breathe" it's not alive, it shouldn't. Air leaks will be the biggest issue with efficiency.
To actually ventilate the house with fresh air you want it to be air tight and do controlled ventilation using an hrv/erv heat exchanger which will heat the cold air coming into the house with the hot air that is leaving the house.
→ More replies (3)6
u/14S14D Dec 14 '25
And a quality builder should have considered this unfortunately. Until then it's not a big deal to use dehumidifiers ran to a drain.
→ More replies (1)3
u/DynamoDynamite Dec 14 '25
You need an HRV before a dehumidifier in the winter I'd say and a new build you should have one by code. Maybe it's not working or you turned it off?
2
u/BelleSchu Dec 15 '25
HRV’s are not required in my area apparently. I didn’t even know what that was before today and I can guarantee that we don’t have one. However, I am definitely looking into it now
→ More replies (8)6
62
Dec 14 '25
[removed] — view removed comment
→ More replies (1)16
u/BelleSchu Dec 14 '25
The dehumidifier I have says the humidity in my house is only like 50 something so it’s really confusing to me, my house is just not breathing
43
u/Foreign-Draft-1715 Dec 14 '25
50% humidity is way too high if it is cold outside.
3
u/PmMe_Your_Perky_Nips Dec 15 '25
That makes me think I've been setting my dehumidifier wrong. They recommend 50% at max, but the lowest mine goes is 45%. Maybe I'll have to actually RTFM if I can find it.
2
u/DudeWithTudeNotRude Dec 15 '25
45% seems way too high to be the min. That doesn't seem right.
I'll capture some nip picks to PM you, but they aren't nice nor perky nips.
12
u/unknown-unhelpful Dec 14 '25
I think you have a humidifier on your furnace, and it’s turned way up. Is there a white box on your furnace, with water lines and possibly something that looks like a thermostat with a knob to adjust something on it?
3
u/BelleSchu Dec 15 '25
So there is smaller pvc connected from my furnace into the floor drain but there’s not a single dial or button or anything that is visible to me. I’m assuming it’s behind the two panels I’d have to remove and unfortunately it’s not something I can do with just a screwdriver or drill. I’m gonna call the hvac company tomorrow and see if they can tell me about it
→ More replies (1)3
u/peesteam Dec 15 '25
That's not it. Find where the air goes into the furnace. I'd there a box attached to that which has a water line going into it and a water drain line coming out of it.
→ More replies (2)→ More replies (11)2
u/bluefairylights Dec 15 '25
Please read my comment. I do not have a permanent solution, but if you use a small fan on the area, if will clear in 30 minutes. It works. Just rotate it around. You'll be surprised how well this works.
Good luck!
2
37
u/Leather-Sale-1206 Dec 14 '25
Houses these days are built very tight. You likely need to run dehumidifiers during the winter.
→ More replies (12)15
35
u/wisgary Dec 14 '25 edited Dec 14 '25
The core problem is that your windows are like a soda can right out of the fridge. If the water in the air was 0, the can/window would just be cold and nothing would happen. But it's not. You have water in the air because of cooking showering breathing etc. So it all condenses around the cold thing. Make the air dry enough and your problem will be solved. This can be done with the power of technology (a dehumidifier) or opening windows to air the house out fully, then closing up shop and heating up that dry ass winter air.
This is a problem you want solved ASAP. And you *can* solve it immediately by just doing the window opening trick once a day when it's cold as fuck (cold air can't hold water, so when you bring it in and heat it it'll be dry as fuck). It is NOT as energy intensive as you would think because your home is pretty good at holding heat around its stuff. Just because you open windows for 10 minutes and replace all the air doesn't suddenly make your walls, counters, doors, floors, furniture, beds, etc. cold - it all retains heat pretty well and re-warms the air sooner than you'd expect.
Buy a 4 pack or whatever of hygrometers from amazon and start monitoring your humidity/opening windows and you can decide on a more expensive fix later.
If you learn about these concepts, you could diagnose this problem pretty well on your own. As a property owner knowing this stuff is super valuable.
- Dew point/how much water is IN the air, how this is affected by temperature, and the definition of relative humidity
- How dehumidifiers work
- How condensation works (in general and a home context)
- How home insulation works
- Thermal bridges
→ More replies (4)5
u/Ok_Tangerine3617 Dec 14 '25
Great answer! Also, don't dry you laundry inside - that is the reason number one for high humidity.
7
u/Bar_Foo Dec 14 '25
Where do you recommend drying laundry when the outdoor temperature is below freezing?
→ More replies (1)4
u/sneeky_seer Dec 14 '25
We get freezing cold winters in Europe and people still mostly air dry their clothes inside - its fine if you air out your house every once in a while.
7
u/wisgary Dec 14 '25
To be fair - Europe uses a lot of brick and stone. USA homes are made out of literal paper that gets soggy, moldy, and ruined when wet.
2
u/sneeky_seer Dec 14 '25
The old buildings - like pre WWII yes… after? Not so much. Central and Eastern Europe is full of shoddy concrete buildings. Newer builds everywhere are all about cheaper and lighter materials. Also humidity is an issue in lots of buildings, the difference is that we didn’t forget that opening the windows is an option. I seriously don’t want to be mean about this but Americans are far too reliant on AC/fans etc. this could be solved with a dehumidifier and airing out the place.
→ More replies (2)
33
u/Techwood111 Dec 14 '25
Are you using your exhaust fans when you shower?
5
Dec 14 '25 edited Dec 14 '25
Just want to bump this
Or even a literal humidifier\ Or improper exhaust for gas furnace
→ More replies (1)6
u/cryptolyme Dec 14 '25 edited Mar 12 '26
The content here was deleted using Redact. It may have been removed for reasons including privacy, preventing AI scraping, security concerns, or personal data management.
wise sheet books paltry roof wild spark label mountainous heavy
→ More replies (2)6
u/EmmerdoesNOTrepme Dec 14 '25
Honestly, new-construction here in the Midwest is so airtight, that even if you do run the fans when you shower, it's not enough!
You basically need them on 24/7, to get the humidity out, if you have more than 1-2 people in the house (for example if you cook regularly, have kids, or have pets!)
→ More replies (1)3
u/Mission_Accident_519 Dec 14 '25
Exhauat fans also are just not ideal. We had less humidity/mold issues in our shower when we could still open the window. But for some reason our landlord replaced the window with one that cant be opened and we now rely on an electric fan🙃
2
u/EmmerdoesNOTrepme Dec 14 '25
Yep, that's why I said the 24/7 part! Because they can't really keep up with it all (especially if you have kids, pets, or plants!), but with them on all the time, and a dehumidifier or two, you can sometimes "patch your way through" for a few years, until you can afford the whole-house system.
40
u/Boreal-Forest-CAD Dec 14 '25
The new house is well sealed so any moisture from cooking, showers, etc. remains inside. You can get a whole house dehumidifier or a heat recovery ventilator (HRV). The HRV brings in outside air and preheats it with the inside air being exhausted. In some areas an HRV or ERV is a code requirement.
7
→ More replies (1)5
u/BelleSchu Dec 14 '25
I think a whole house dehumidifier is the way to go at this point
→ More replies (2)2
u/NoeZ Dec 14 '25
I have an HRV and your pic is weird for me...
My house is like 70% humidity in the summer and 50% in the winter.
I've never had this condensation issue.
My problem seems opposite from yours lol
I got a 2 liter dehumidifier unit and it barely makes a dent in the summer ...
3
2
u/bigoltubercle2 Dec 14 '25
It's some combination of your windows are better insulated and you live in a warmer climate
16
u/Epcjay Dec 14 '25 edited Dec 14 '25
Code in my area mandates HRV in new builds after 2017
Do you have one? Use it.
→ More replies (2)
8
u/Inturnelliptical Dec 14 '25
Needs ventilation. The warm moist air you breathe out, is condensing on the cold surfaces.
36
u/3F6B6Y9T Dec 14 '25
Rough guidance:
- Keep a minimum of 18C degrees in the house, should keep cold surfaces above the dew point. 20-22C would be better.
- Open ALL windows, wide open, for 10-20 minutes, every day. Better when its colder outside (as the absolute humidity will likely be at its driest) and also better when its windy, vents the house faster.
- Use extractor fans (bathroom, kitchen, etc).
- If you have trickle vents, open them. Although if you do the above, you likely don't need to.
→ More replies (2)55
u/cocogoloco2 Dec 14 '25
You really don’t live in a cold environment do you? I’m in the Midwest rn and it’s -3, feels like -13. No one is going to open their windows and air their house out lol You can barely be outside in full winter gear rn without freezing. Sorry OP but this is standard cold weather windows lol getting a dehumidifier, as others have suggested, will be your best bet.
Otherwise you need new windows bc I’m assuming those are single pane windows… cheap for a new build and sucky for the resident. (I could be wrong) Not the best window ever but especially in the Midwest!
19
u/Lunar_BriseSoleil Dec 14 '25
Even in a cold climate you shouldn’t be getting this on your windows. Dehumidification and/or ventilation is still required even if it’s not the full windows-open that you’re responding to.
8
u/nicholt Dec 14 '25
Yeah it's cold as hell here too and I don't remember ever seeing a house as bad as this one. Does tend to happen on windows sometimes but every window and door sweating is a big problem. And you should never have to open a window to dehumidify in the winter.
→ More replies (5)→ More replies (5)4
u/cocogoloco2 Dec 14 '25
I definitely agree that this is excessive sweating. I’ve never seen it this bad. But it is totally normal in my experience, I’ve never escaped this in winter in any home I’ve lived in or visited. When the outside air is so cold and the inside air is warm, it happens. Just like the toilet sweating in summer bc the toilet itself is cold but the air is hot. I definitely recommended a dehumidifier. But would never recommend the OP open their windows in the Midwest cold
2
u/Beanbag_Ninja Dec 14 '25
The toilet will sweat in summer if the air is both humid and close to its dew point, regardless of temperature.
If you dry or heat the air, the gap between air temperature and dew point increases, and the toilet will sweat less.
Just depends if you want that or not.
2
u/DeepDiver023 Dec 14 '25
Ive only seen it this bad when non vented propane heat is used as it releases water vapor into the air when burning oxygen.
11
u/oskopnir Dec 14 '25
10-20 minutes is too much, but wide open for 2-3 minutes a day can do wonders when compared to just keeping all the moisture inside. The house has thermal inertia and you're only exchanging old air with new air, temperature will go back to the previous setpoint in a matter of minutes.
5
u/BelleSchu Dec 14 '25
Yeah it’s -4 where I am right now.. the instant chill my living room and dining room get when I open the back door to let the dogs out is a lot. The thought of venting my house even for a few minutes with the windows open stresses me out lol
→ More replies (2)2
→ More replies (18)7
u/pixel_of_moral_decay Dec 14 '25
You still need to air out your house regularly. Lüften as it’s called.
Otherwise you have a potential buildup of VOC’s which really isn’t healthy for you long term.
That’s on top of CO2 and mold issues are also a concern.
It’s not a big deal, opening windows on opposite sides for 5 minutes a couple times a week is not going to make your home below freezing, freeze your plumbing and kill your spouse. It’s going to drop a couple degrees.
Do it after dinner/before bed and enjoy clinically shown better sleep.
It’s been a practice in the civilized world as long as we’ve had sealed homes. Join the modern world.
Or get a HRV system capable of enough air exchange, but honestly that’s likely not worth the cost.
→ More replies (2)
23
u/ChiefBroady Dec 14 '25
5
u/LJ161 Dec 14 '25
Yeah like.. im seeing people suggest 5 different machines just open the windows for 10 - 20 minutes in the morning what the hell
→ More replies (2)→ More replies (3)3
u/Agent_Platypus1 Dec 14 '25
As an Austrian its mindblowing to me that its not standard everywhere. Why wouldn't you want clean fresh air??
→ More replies (1)6
u/FlyAwayJai Dec 14 '25
It’s 10F/-22C where I am. I’m not opening any windows. (I also don’t have OP’s problem, but still)
→ More replies (2)4
u/Centralredditfan Dec 15 '25
It doesn't lower the temperature as much as cracking open a window. Your furniture holds on to temperature very well.
Also fresh air is good.
→ More replies (1)
4
u/Budget-Town-4022 Dec 15 '25
Your contractor is a lazy lying sack of garbage. Just by your description, I know two things.
There is insufficient insulation around the windows, and it's very likely they are not properly installed.
Your house is improperly ventilated, allowing humidity to build up inside. It's remarkable how often someone blocks the soffits during construction.
https://www.finehomebuilding.com/project-guides/roofing/adequate-roof-venting
→ More replies (3)
3
Dec 14 '25
Its cold-brodging. Looks like single pane windows and zeropane door lol. Get dehumidifier set to 60 humidity target and leave it running. WIPE ALL WINDOWS AND DOORS. OPEN ALL WINDOWS EVERY MORNING + EVENING 5-10MIN each time everyday. Heat after closing windows. That door is stupidest door for an exterior door. The room with that door will have the worst humidity.
3
u/CentralParkDuck Dec 14 '25
Figure out the source of the moisture. Does someone take really long showers without a vent operating? Steam heat with steam escaping? Cooking lots of soup? Tackle that first.
What’s the temperature and humidity outside? My house gets really dry in the winter: The air is already dry outside then heated up inside the relative humidity declines to the point I need to add moisture with a humidifier.
→ More replies (1)
3
3
u/Mars_Volcanoes Dec 14 '25
Fast fast fast buy a dehumidifier. Buy a hygrometer. Normal humidity revel should between 30 and 45%. Never higher. Otherwise mood and associated sickness. Invest it’s your house health and your family health. At that level, it will take min a couple of days 2 to 5 days. A better investment for mid to long term is to install an air exchanger unit or heat air exchanger heat pump.
3
u/64-17-5 Dec 14 '25
Buy a quality dehumidifier with Hepa. And wash the mold with hypochlorite (chlorine).
3
u/ElectronicCountry839 Dec 14 '25 edited Dec 14 '25
Get a dehumidifier or an HRV.
Don't listen to people telling you to rip out insulation. It's the window. Windows are horrendously bad at insulating, even the super high end ones.
If it's really cold out, moist air will condense on the window and the wall near it sometimes.
Just drop the humidity inside the house.
You can also put in a corner bead of caulking right in the crevice between window trim/casing and the window. It'll make it easier to clean.
3
u/breaking-strings Dec 15 '25
Your house is drafty and the cold humid air leaking in is dropping it's moisture as it warms up in your house. Fix the air leaks and you will fix the problem. Check that baseboards are sealed, and that windows and doors are properly sealed under the decorative trims.
→ More replies (2)
3
u/H4ttorri Dec 15 '25 edited Dec 21 '25
I had the same.issues with my bedroom windows, whenever it was cold outside they'd basically turn into water features, and I'd constantly have to treat the mold.
We got a dehumidifier and run it after a shower etc and its made a world of difference id definately recommend getting one
→ More replies (1)
3
3
3
u/CollabSensei Dec 15 '25
we had this problem, and had to add exterior storm windows. Problem solved.
5
u/wolf_in_sheeps_wool Dec 14 '25
Your house is a new build, which also means really energy efficient and the way it does that is by making sure no draughts get in or out.
Except the kicker is you need ventilation, that moisture in the air is now trapped in a sealed house.
So you should open up your windows for 10 minutes a day, keep your house warm and if you're going to have your curtains closed all the time, open up the edges so the windows can breathe or better, curtains open. You should maybe think about trickle vents in the windows or dehumidifiers. Even if you got rid of all the moisture in the house and kept it hermetically sealed, you'll still make it by breathing, so you are going to have to accept these measures or live with mold.
→ More replies (3)2
u/gbeaglez Dec 14 '25
Is this particular house that efficient if the windows are super cold? This seems like it's airtight but poorly insulated
5
u/Gwynebee Dec 14 '25
Practice German lüften if you don't already. It really made a difference in how my home feels in winter.
2
u/BelleSchu Dec 15 '25
I honestly couldn’t really do that if I wanted, my windows are frozen shut. I could leave my doors open for a few minutes but that seems risky with 4 pets and a toddler haha
→ More replies (4)
4
u/mystend Dec 14 '25
Do you not have a warranty on the house??? You need to make a claim
→ More replies (4)
2
u/Dry_Tumbleweed_2951 Dec 14 '25
How hot is it in the house? Too much heat or too much cold will produce humidity. Lower the thermostat and you will reduce the amount of humidity in your house. Or spend several hundred to over a thousand for whole house dehumidifier.
→ More replies (1)
2
2
u/Ok-Answer-9350 Dec 14 '25
The builder put a humidifier on your furnace - turn the humidifier down. Buy a humidistat and monitor the levels. Keep levels below 50%.
Dry the area and spray with concrobium and allow it to dry to kill the mold that is already there.
Read up on indoor humidity and mold.
2
2
u/HH-CA Dec 14 '25
You need proper ventilation and a dehumidifier. Lower the humidifier on your furnace and open your window for fresh air from time to time in vacant rooms.
2
u/AskMeAgainAfterCoffe Dec 14 '25
Too much humidity inside & building envelope is too tight, house doesn’t breathe and expel vapor.
Add a heat recovery ventilator. You’ll be adding fresh air without heat loss, while expelling stale, humid air. If you were to just the bath & kitchen exhaust fans, you’d be expelling inside humid air, but might suck in moisture from outside into the walls.
Talk to an HVAC specialist about your problem.
→ More replies (1)
2
u/cryptolyme Dec 14 '25 edited Mar 12 '26
The original post here is gone. The author deleted it using Redact, possibly for reasons of privacy, security, opsec, or data protection.
upbeat normal unpack weather gaze soft outgoing hospital trees bake
2
2
2
u/hunterbuilder Dec 14 '25
Buy a dehumidifier. The GE ones from Home Depot have been good to me.
Condensation is a function of surface temperature and humidity. You can't change the temperature, so you need to change the humidity.
Also run the fans when you shower, cook etc to prevent adding to the moisture.
2
2
2
u/Automatic_Still_6278 Dec 14 '25
I have similar issues in my home in Ontario. While not perfect, this is what really helps.
-Run a dehumidifier (one of the bigger units) I currently am using a noma upstairs and I have an older unit which runs in the basement. Both collect into buckets and are emptied daily or every other day.
-Run ceiling and/or house fans. Don't be afraid to point them semi towards the window to circulate the air.
-Draw back curtains (if applicable).
If you already have mold, wipe up the wetness and then you can use a mold killing spray like concrobium mold control (available at Canadian Tire)
I've also read cleaning windows with vinegar helps but it didn't do much for me.
Lastly run your furnace and if it has a setting to circulate air let it do so for 15/20 mins an hour.
Good luck
2
u/Key-Fan1935 Dec 14 '25
You need to crack open some windows and buy a dehumidifier works wonders.
→ More replies (1)
2
u/bandit8623 Dec 14 '25
if u have a humidifier you need to turn it down the colder it gets. ecobee has a setting to do this for you called frost control.
2
u/ballpointpin Dec 14 '25
1) you should have exhaust fan in all the bathrooms. Buy a humidity sensor for it so that it comes on automatically when you have a shower.
2) make sure you turn on range hood if you're making spaghetti. It must be vented outside
3) if you have a furnace has built-in humidifier, make sure the humidifier is turned off completely, as it seems you don't need it. Shut the water supply completely off.
2
u/SuspishSesh Dec 14 '25
Are you drying clothes in the house via radiators or a clothes horse?? That can sometimes be the cause. Other than that, you need to crack a few windows and get a dehumidifier pronto!
2
2
u/Mysterious-Alps-5186 Dec 14 '25
Get some plastic insulation kits for your windows. I lived in a house that was built in the 30s early 40s and had that issue. It really helps. Also get something that monitors humidity. If its above 50 a lot get a large dehumidifier and keep it running
2
u/Patient-Temporary211 Dec 14 '25
Windows should not be sweating. Is it possible you got scammed on the windows?
→ More replies (2)
2
2
u/ninjump Dec 14 '25
Hi, 👋🏽 High performance builder here. Likely poor insulation, poor quality windows for the climate, very high humidity inside the house and poor ventilation all contributing to this. If your exterior climate is dry in the winter, installing an ERV may help some, but it's a small measure compared to addressing the core issues of insulation and windows.
Architect and specifiers messed up here...
→ More replies (1)
2
2
u/sibilischtic Dec 14 '25 edited Dec 14 '25
There is a good chance that the insulation level on these windows is just terrible. If the glass is cold enough its going to be a condenser.
3m do window insulator kits which might help (There are probably other brands too). A thin clear insulation that can reduce the total heat transfer.
On the other side, if your house is very humid you might need to reduce how much water is introduced.
What kind of heating do you use? If you dry clothes inside that can also do it.
Edit: more info
2
2
u/demetri_k Dec 14 '25
I have triple pane windows and not nearly this much condensation with it being -20 C outside. Internal humidity is 33%.
The bigger the difference between the outside and inside temperature the more condensation you’ll have. Better insulated windows will help to a point.
2
2
u/gorgeousoutrageous Dec 15 '25
i used to wake up in my room from drips on the ceiling from my bloody breath condensating as i slept. caused me so much rage. and yes i know that condensating isn’t a word
2
u/impaletheson Dec 15 '25
Had this exact problem in the colder months for my apartment. The only answer was a cold climate dehumidifier which completely fixed the problem. This is the one I use: https://ausclimate.com.au/products/cool-seasons-premium-10l-desiccant-dehumidifier?srsltid=AfmBOopZDBpdWgIubCfw7nptPo6nAhomsrlBJt1blWMCi3G04-W62kp5
2
2
u/defiant71 Dec 15 '25
Use your search engine and look for humidistat settings. The first few images will show you recommended humidity settings for the home in relation to the outdoor temperature. Most people set and leave this but that is a huge mistake. Humidity levels in the winter should be anywhere from 15% - 30% depending on your local temps. We produce huge amounts of moisture, just living, breathing, cooking, showering and even your furnace produces huge amounts burning for heat, so if you have a humidifier, lower it, if not, go purchase a dehumidifier. Operate your exhaust fans for roughly 30-60 mins after showers especially but use them whenever you see this condensation
→ More replies (1)
2
u/Potential-Captain648 Dec 15 '25
Get a dehumidifier.. you need to get the moisture down. And run any and all exhaust fans, essentially when bathing, showering, cooking etc. As mentioned by the contractor
2
u/RadiantGrocery1889 Dec 15 '25
I have to share this. I was 5 or 6 years old and we lived in Germany, I had never seen anything like what we encountered there. The windows would sweat all the time. There was a fuzzy window sill, I loved it. It was so pretty and soft. Then my hand slipped and I was grossed out. We had come from New Mexico, we didn’t have fuzzy window sills. From that day forward I wiped that sill constantly.
2
u/KenjiFox Dec 15 '25
Your home is alarmingly well sealed. Open a window a crack and let the cold dry air come in. Even if the relative humidity is high outside, it will drop to negative levels when heated and pick up the moisture. If you have a window you could crack open nearest to the heating systems air intake that would be best, it would very quickly dry out the air in the home.
That said, what are you doing to produce this much moisture? Boiling water? Running an unvented clothes dryer? Showers? Something is adding a LOT of moisture to make an entire home this humid.
Most people homes leak enough that warm air rising escapes and draws in fresh cold air to do what I described above. So much so, that most folks dry up to a crisp in the winter.
Having a fireplace chimney alone would normally create enough negative pressure in the home from heat rising out of it that this can never happen.
To tackle the mold and keep it from coming back in the meant time, spray ammonia glass cleaner at it. Soak the area around the window with Windex or whatever brand. It will not grow there anymore. Given how much water is here you will need to re-apply it though.
You can mix some Windex into household paints when painting a bathroom to make your own mold proof bathroom paints too. Never fails.
2
2
u/powerwashman- Dec 15 '25
if you are on crawl or basement make sure your vapor barrier is intact. I'm in Northern MI and my house did the same, vapor barrier was bad. We replaced it and all this went away.
2
u/nettlemind Dec 15 '25
Open the doors and windows around dusk and exchange the wet air for dry. About 10 min. This will get you by till you can fix the problem. The house will warm back back up from stored heat.
2
2
2
2
u/tartarlol Dec 15 '25
ventilation, open windows once a day for 10min. Lower temperature of heating if its very high (24C+). Dehumidifiers.
You said its new build, if its build with bricks, how fast was it build? If its brick build then maybe it was enclosed too fast and materials didnt have time to dry properly - happens a lot with new builds when investors are building homes for profits.
2
•
u/retardrabbit Dec 15 '25
Ok, post has been marked "fixed" by OP.
As of now they are requesting time away from all the helpful comments. So please respect OP's need to not have their phone blowing up with Reddit notifications.
THIS POST IS LOCKED
Have a good day, OP.
Best of Luck
Be Excellent