Home & Garden

Window Condensation - New Home

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  • Dec 17th, 2020 10:50 am
[OP]
Deal Addict
Sep 15, 2006
1235 posts
527 upvotes
Ottawa

Window Condensation - New Home

This is my first time owning a brand new built house and now that the temps in Ottawa are dipping below -20C I'm getting condensation on windows. I thought the humidity levels needed to be between 40-60% because of the hardwood flooring to avoid issues like cracking. My furnace has a humidifier with a little dial on it, it's currently set to between 30-40% (no numbers just a range between 10-75%) and internal humidity level is currently 37%. I do have an HRV system and tbh it's been off, I just realized this should be on during the winter, correct? (again never owned a new house, excuse my stupidity here). There are three settings, Econo, Ventilation and 20 min/hr, which should I put it on? I just worry about mold/mildew in the house with two babies but also worry about the hardwood floors. Any help would be appreciated.
25 replies
Deal Fanatic
Dec 5, 2009
5676 posts
3428 upvotes
Try searching because this gets asked frequently. You probably have cheap builder grade windows and when it gets very cold humidity levels need to be lower.

First thing I would do is buy a humidity gauge (costs a few bucks) and find out how much humidity there in in your home.

From there , there are guides online that indicate what humidity to set at what outside temperature.
[OP]
Deal Addict
Sep 15, 2006
1235 posts
527 upvotes
Ottawa
fdl wrote: Try searching because this gets asked frequently. You probably have cheap builder grade windows and when it gets very cold humidity levels need to be lower.

First thing I would do is buy a humidity gauge (costs a few bucks) and find out how much humidity there in in your home.

From there , there are guides online that indicate what humidity to set at what outside temperature.
The thing is, they're the same Jeld-Wen windows that were in my previous home but it was older and not as energy efficient, no humidifier so the humidity just naturally dropped into the 20's so I didn't get the condensation. I have gauges in every room and they're roughly around 35% but with the guids online it should be in the 20's . I'll do a search on here about how/what to set the HRV to.
Deal Fanatic
Aug 29, 2011
6158 posts
3223 upvotes
Mississauga
Brand new homes release a lot of moisture in their first 6-12 months, especially from the basement floor and foundation walls. Give it time and things will dry up. The suggestion to get a separate hygrometer is a good one so you can monitor actual levels. Some other suggestions: make sure to run you bathroom fans during and 20 minutes after taking a shower, run your range hood fan when cooking, etc.

Our home is almost 30 years old and it struggles to hit 30% RH in the dead of winter. And that's with a furnace-mounted humidifier running 24/7.
[OP]
Deal Addict
Sep 15, 2006
1235 posts
527 upvotes
Ottawa
mrweather wrote: Brand new homes release a lot of moisture in their first 6-12 months, especially from the basement floor and foundation walls. Give it time and things will dry up. The suggestion to get a separate hygrometer is a good one so you can monitor actual levels. Some other suggestions: make sure to run you bathroom fans during and 20 minutes after taking a shower, run your range hood fan when cooking, etc.

Our home is almost 30 years old and it struggles to hit 30% RH in the dead of winter. And that's with a furnace-mounted humidifier running 24/7.
That makes sense, thanks for the answer. I did find an old thread in here asking a similar question and someone from Ottawa replied so that helped. I set my HRV to 20 min/hr as a start, lowered my humidifier and I'll keep an eye on the condensation. In theory once the RH lowers in the house the condenshould stop.
Member
May 15, 2017
202 posts
180 upvotes
engman13 wrote: This is my first time owning a brand new built house and now that the temps in Ottawa are dipping below -20C I'm getting condensation on windows. I thought the humidity levels needed to be between 40-60% because of the hardwood flooring to avoid issues like cracking. My furnace has a humidifier with a little dial on it, it's currently set to between 30-40% (no numbers just a range between 10-75%) and internal humidity level is currently 37%. I do have an HRV system and tbh it's been off, I just realized this should be on during the winter, correct? (again never owned a new house, excuse my stupidity here). There are three settings, Econo, Ventilation and 20 min/hr, which should I put it on? I just worry about mold/mildew in the house with two babies but also worry about the hardwood floors. Any help would be appreciated.
Make sure you windows aren't covered by blinds or curtains. If they are, open them up. This helps tremendously.

37% sounds about right. I personally wouldn't want it any lower.
Deal Fanatic
Aug 29, 2011
6158 posts
3223 upvotes
Mississauga
Exactly. Bring the RH level down and window condensation will clear up significantly - though you'll probably still see some in the corners of the glass simply because airflow isn't consistent across the pane.
[OP]
Deal Addict
Sep 15, 2006
1235 posts
527 upvotes
Ottawa
turtler wrote: Make sure you windows aren't covered by blinds or curtains. If they are, open them up. This helps tremendously.

37% sounds about right. I personally wouldn't want it any lower.
I'll do that now
Member
May 15, 2017
202 posts
180 upvotes
mrweather wrote: Brand new homes release a lot of moisture in their first 6-12 months, especially from the basement floor and foundation walls. Give it time and things will dry up. The suggestion to get a separate hygrometer is a good one so you can monitor actual levels. Some other suggestions: make sure to run you bathroom fans during and 20 minutes after taking a shower, run your range hood fan when cooking, etc.

Our home is almost 30 years old and it struggles to hit 30% RH in the dead of winter. And that's with a furnace-mounted humidifier running 24/7.
It doesn't look like humidity within the house is much of an issue if his readings are correct (37%). If you have your window coverings closed in the middle of winter, condensation is almost certain unless your house has rock bottom RH. If I close the blinds overnight on my super GreenON windows, they get trace amounts of moisture in the bottom corners (house is 35-40%). Once I open the blinds, it evaporates quickly. I just keep them open to avoid any at all.

I think my skin would feel like sandpaper if my house was below 30%!
Banned
Sep 14, 2020
437 posts
239 upvotes
45% is the optimal. 30-60% is acceptable range. So the closer you get it to 45% the better. A little condensation is normal when it's cold outside.

The hygrometers from dollarama are great. Bought 4, shows the same as the 4 5x more expensive thermopros I got from amazon.
Deal Fanatic
Jan 25, 2007
9937 posts
5228 upvotes
Paris
Any builder installed JW windows will be low end unless you know exactly what you were buying and paid for JW windows made in their Winnipeg factory. Most likely yours are DF made in Quebec, and I REALLY hope they weren’t JW united made in Toronto.
Deal Addict
May 23, 2009
2829 posts
1295 upvotes
Mississauga
How much condensation are you seeing on the windows?

When its -20C outside and your indoor RH is at 37%, I think it is pretty hard to not get condensation on your windows. Drop your humidity about 5-10%

-5C to -10C should have no condensation at 37% but I think -20C is pushing the limit of the windows. Again it depends on how much condensation you are seeing.
[OP]
Deal Addict
Sep 15, 2006
1235 posts
527 upvotes
Ottawa
Jerico wrote: Any builder installed JW windows will be low end unless you know exactly what you were buying and paid for JW windows made in their Winnipeg factory. Most likely yours are DF made in Quebec, and I REALLY hope they weren’t JW united made in Toronto.
Now you got me curious and worried about the United Windows, what's the issue with those? Unfortunately I can't confirm which jeldwen windows I have, it is a custom home had I known there were significant issues with some windows I would have discussed this a bit more.
Deal Addict
Nov 17, 2012
3212 posts
2172 upvotes
Toronto
I wouldn't sweat the hardwood issue.

I have had hardwood floors for 26 years of home ownership in 3 different buildings including my 3 season cottage and I've never paid any attention to humidity levels. Mostly because I can't effectively control them. My current home is 4 finished floors and 100+ years old with crappy HVAC. I have a humidifier on the furnace that I leave on full blast all year.

At the cottage, where I installed solid birch hardwood a few years back, there is zero control and it's whatever the ambient temperature and humidity are. Going up there on the weekend and will fire up the propane stove to warm it up and will then let it freeze again.

Never had a problem.
Deal Addict
User avatar
Sep 27, 2006
3621 posts
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Not so easy there Ma…
engman13 wrote: This is my first time owning a brand new built house and now that the temps in Ottawa are dipping below -20C I'm getting condensation on windows. I thought the humidity levels needed to be between 40-60% because of the hardwood flooring to avoid issues like cracking. My furnace has a humidifier with a little dial on it, it's currently set to between 30-40% (no numbers just a range between 10-75%) and internal humidity level is currently 37%. I do have an HRV system and tbh it's been off, I just realized this should be on during the winter, correct? (again never owned a new house, excuse my stupidity here). There are three settings, Econo, Ventilation and 20 min/hr, which should I put it on? I just worry about mold/mildew in the house with two babies but also worry about the hardwood floors. Any help would be appreciated.
Actually that was a sustained -24 to -27 with wind chill.
https://weather.gc.ca/past_conditions/i ... tation=yow
Just give the windows a quick wipe with a towel in the morning and your done. The mold mildew issues are overblown, if anything develops over time just wipe off with a paper towel, a touch of diluted bleach if mildew were allowed to build up over weeks. Kids should not be brought up in a sterile environment. Bacteria/germs can be a good thing it builds up the immune system.
https://www.webmd.com/parenting/feature ... dirt-germs
The humidity in my previous home rarely dropped below 50% as the portion with the inaccessible crawlspace wasn't covered with plastic or anything like that. Nobody got sick from any mildew and most of the windows were wood and very susceptible to that.
Deal Addict
Jan 15, 2017
3898 posts
3354 upvotes
I agree with many of the suggestions noted above.

When the warm 22 - 23 degree room temperature air inside hits that cold window with -20 outside, condensation is going to happen. Condensation on really cold winter days at the bottom of the window is not a problem. Simply take a towel and wipe it and forget about it. If you notice the condensation between the window panes that is an indication of a window problem.

You will notice that windows that have blinds or closed drapes will experience more condensation due to a lack of air flow. We always raise up the bottom of our blinds in the winter to increase air flow. Plus, I always remove the interior screens from the windows this time of the year and it helps with condensation.
Banned
Sep 14, 2020
437 posts
239 upvotes
Drapes and especially blinds will increased condensation by A LOT. All that room warm air with moisture trapped between blinds and windows will get colder and colder and that moisture will go right on the windows
Deal Fanatic
Jan 25, 2007
9937 posts
5228 upvotes
Paris
engman13 wrote: Now you got me curious and worried about the United Windows, what's the issue with those? Unfortunately I can't confirm which jeldwen windows I have, it is a custom home had I known there were significant issues with some windows I would have discussed this a bit more.
That factory is focused on making the absolute rock bottom priced windows, and no corner is too round for them to try and cut it further. And it shows in their prices, and quality.
Deal Addict
May 23, 2006
1017 posts
214 upvotes
Vancouver
Is the source of heating close to your windows? i used to have home where the source of heatings are close to windows (e.g. forced air or baseboard), and that always cause condensation in my windows. l

Now, i have radiant heat where the source of heating is distributed evenly througout my house. i don't noticed condensation in my house. It's also much more comfortable.

I live in Vancouver, BC
Member
Dec 6, 2020
375 posts
353 upvotes
Keep in mind that window manufactures have multiple glass options and will use whatever the buyer (in this case, the homebuilder) asks for. All else held equal, the humidity level you can get away with depends almost entirely on the insulating properties of each window's glazing unit and not on the window brand. What works in one house with Jeld-Wen windows will not necessarily work in another house with Jeld-Wen windows, unless the windows in both houses use similar glazing units.

Acceptable humidity will also depend on the outside temperature. What we can get away with in coastal BC won't work in the rest of Canada.

Just bring the humidity down as far as it needs to go to stop the condensation, or until the air is too dry to be comfortable.

A good builder should choose windows that will allow for enough indoor humidity for comfort and to protect wood flooring, but that might require using very high end windows (triple or quad-glazed argon low-e) that may be unaffordable for the homebuyer.

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