Moisture on Our Windows, Inside the House

Updated on December 18, 2008
E.K. asks from Seattle, WA
9 answers

We're fairly new to the Pacific Northwest and I'm baffled by the amount of moisture sitting on the inside of our windows now that the weather's cold outside. There's water all around the window frame and several little pools that sit on the window ledge. I hadn't looked closely at the ledges for a few weeks and today noticed quite a bit of mold growing there. Yuck! Lots of tiny black pieces and a few patches of fuzzy green. Is this common? Would new windows get rid of the problem? They are double paned windows that are fairly old. Any advice? Yuck!

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answers from Seattle on

Super common.

First off: 10% bleach. Now.

Secondly....if it's a structural problem new windows would solve SOME of it. (note the some) It could be many many many of any one, or a combination, structural problems; from as simple as needing new seals to the framing actually being damaged. If you only get drips when it rains...that's your key.


If the condensation starts in October and lasts until late May, welcome to one of the dampest places in creation. We actually have more varieties of MOLD in this area then anywhere else in the world save ONE rainforest I can't remember the name of, and it's not the Amazon. Yuck. Most of it's harmless...unless you don't consider sinus issues harmless.

Moving Along...

You don't have what area you live in on your profile, or mention what type of home you have. Areas around here TEND to indicate style & decade built. If it's an apartment, and you look in the fine print on your lease, it's one of those things that SHOULD be covered. If you live in a house, the KIND of house you live in will help determine the problem....but regardless of the type...a vast majority of houses in this area are insufficiently vented. And worse...many DIY'ers have vented into crawlspaces and attics...which then FILL with mold. Sometimes the toxic kind. So put that on your list to check out. Wheee.

The types of houses that do BEST with moisture are those built prior to WWI and are NOT cement-brick-stucco...especially ones that have been retrofitted with kitchen & bathroom vents. Tens of thousands of houses (nearly all of Mountlake Terrace for example), were built on the quick by the military after each of the world wars...and if you're in a cinderblock house you have my condolences. Rented one for two years. Lived in a brick house for 8 years. Brick, cinderblock, & cement all need double wall insulation or you may actually notice your walls "weeping" at night. If you have any of these kinds of houses make sure your furniture is pulled at least an inch away from all walls. And dig french drains as a stopgap measure. Dehumidifiers are a big help as well.

Anyhow...I could go on...if you'd like me to shoot me a message with your home type.

The simplest "fix" however is this: Leave about an inch gap between your blinds and the casing, leave curtains open as much as possible, keep the heat up as high as you can afford (similar to using a hairdryer to clear off the steam from a mirror), & run your fans religiously during cooking & bathing for about an hour.

Good Luck...and welcome to the city. The very very damp city :)

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answers from Seattle on

Just wanted to say we have the same problem here - our windows are new - well within the last 10 years.

We just remember to clean it up on occasion with vinegar and water.

Now I'm not sure if we had the problem before since I may not have noticed it - but I noticed it happened once we insulated the house - honestly I think before there were enough leaks to keep things moving.



answers from Seattle on

Hi E.,
If you have a crawl space, check if there are any plumbing leaks in your crawlspace. We had this happen and the first sign of it was major condensation on the windows. we ended up with $20,000 damage (was covered by insurance). Good luck!



answers from Seattle on

We've had this problem on pretty much any aluminum framed windows we've had (much worse on the single-paned ones). I have to clean them with a bleach/water mix when it gets bad.

The kicker is that around here a house that's too sealed up or one that's pretty cold and uninsulated seem to both have the problem. We've also found that it really depends on the caulking. You'll want to re-caulk all around the outside of your windows to start. If you have mold on any of the caulking on the inside of the windows, remove it and re-caulk with a mold/mildew resistant caulk (like silicone). The guy that owned the house prior to us used some kind of caulk that LOVES mold. ARGH! Perfectly good, vinyl windows get mold ONLY where this crappy caulk is. It's so frustrating.

It's the first place to start. Everyone else had great suggestions too (about decreasing the humidity inside your home) and figuring out what year/style your house is so you know if you need more insulation. Good luck! I know this is something we never had to deal with when I grew up in the dessert. ;-)



answers from Seattle on

Are the windows aluminum or vinyl? With vinyl windows you shouldn't have this problem. Good luck!



answers from Seattle on

i am a transplant too but really haven't seen this problem in the apartments and houses that i have lived in over the last 7 years (4 of them), so i might advise that you not just assume it is a northwest thing, and get it checked out just a little more.



answers from Seattle on

Sometimes houses are so well insulated these days they don't breathe and let moisture out. There are things you can do.

Have an inspection done to assure yourself you don't have scary black mold growing that needs professional removal and to assess whether you to change existing venting.
Always run the fan while cooking (make sure your vents all go to outside).
Run the kitchen fan if you are emptying the dishwasher while it is still warm.
Wipe down the shower enclosure after you're done (less water to evaporate into the house).
Buy a dehumidifier (and get ready to drain/empty it daily)
There's a product called Damp Rid that's a chemical dehumidifier (often sold in hardware and drugstores or where boating supplies are sold. It's not as good as the plug-in dehumidifier, but it will keep your closets from getting damp. Ours usually collects about a pint a month from each closet during the winter. The kind that hangs in your closet can be kept out of reach of the kids (and/or pets.



answers from Seattle on

I read your post awhile ago but i wanted to make a buyer be ware comment.. we have an old 1950 's house in seattle with old double pain windows that have wooden frames.. anyhow we get mold and I have to clean it up but our windows are really old.. so we have been thinking about windows.. so we thought great I will have pengiun windows out for a quote as I have seen there window installer trucks around.. low and behold the lady comes over and her 1 hour presentation turned into 4 hours.. for 15 windows they wanted 35,000 dollars oh but we could finace at (a high rate) then she told us oh if we signed tonight and tonight only we could save almost 4,000 dollars.. and i started to get paniky great looking windows but my gut told me something wasn't right why did we have to sign tonight.. i said no.. and she got so rude and keep trying to sell us a lower package of a few windows at a time.. thank the lord we follwed out gut and didn't cave in.. next time i will google a company first.. I learned that they have a lot of bad reviews.. on a side note we had another window company gives a quote for 15,000 big difference.. still tramatized by the window sales people.. I will stick to bleach water to keep my old windows clean.. on a side note my friends that have new houses have i think milgard vinyl windows and no mold problems.. someday i will replace with vinyl.
sorry to rant.. just wanted to let you know about our experience with pengiun..



answers from Seattle on

Yes--I have experienced exactly the same thing. It was the top floor of an apartment building in Seattle (Ballard) that had two culprits: 1. electric heat and 2. aluminum-framed single-pained windows. It was SO bad I literally put a towel all along my window sil and changed it every other day! Once a week I diluted some bleach (would probably use vinegar now) and just ran it along the sill on a wet washcloth to prevent the mold from growing.

Do you have electric or forced air heat? My husband purchased the house we live in before I met him, but he said after moving to Seattle he lived in several apartments with electric heat that had issues similar to my old apartment (none quite as bad). He installed forced air heat throughout the house we live in (which was easy because the old owners had oil-heat they had not been using and electric in-wall heaters in every room), so the vents were in place, it was switching the furnace to a gas one instead of oil-burning.

I eventually purchased a dehumidifier when I lived in the apartment and that seemed to help. Years after I moved out, the landlord finally switched to all vinyl double-paned windows--when I drive by it this time of year, the upper floor windows don't look all fogged up and/or dripping with moisture like they used to.

Good luck! I remember how icky all that was.

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