I am renting out my condo since I had to move across country. The tenant just informed me the window is "sweating" and water is leaking in and settling in the window sill. It looks like it's causing mold. The windows are double pane and the condo was built in 2006... so it's not that old.

Any help or advice would be greatly appreciated! Thanks in advance!!

He sent me the following pictures:

12/7/2010 12:13:25 AM

dehumidifier

12/7/2010 12:35:53 AM

Keep your blinds open during the day. This may not fix the problem but it will help.

12/7/2010 10:03:26 AM

tell him to wipe the water up....

so is the window sweating or is water leaking in?

they are two diff things...

12/7/2010 12:03:23 PM

looks like sweating imo. my bathroom window & sidelight windows at the front door do this all the time when it's really cold outside. it's just a temp difference & humidity issue. wipe the water up before it collects & it won't grow mold.

12/7/2010 12:06:44 PM

I stopped by to look at the window is sweating. The tenants keep the place pretty warm and the blinds are always shut. I told them it'd be less severe if they opened the blinds. I also wiped up the puddles and mold and left a large DampRid to see if that helps (which it should). I don't know what the permanent solution is.

12/7/2010 12:41:40 PM

Better windows.

12/7/2010 1:02:18 PM

Better tenants.

12/7/2010 1:31:57 PM

once it's not -234891397 degrees outside it'll be better.

12/7/2010 1:49:30 PM

It's just a function of cold temps outside, warm temps inside, and moisture in the air. You can't really do much about the outside or inside temps, so you should probably attack the issue with moisture control. If this is a first floor condo you're the unit that will receive all the moisture that permeates through the concrete slab or the floorboards if it's on a foundation. Not a lot you can do about that.

- Is there a bathroom nearby? Tell them to run the vent for 20 minutes after showering if they aren't already doing it.
- Do they have the HVAC vents closed in this room? People often do this in rooms that don't get a lot of use to save money on their heating bill, but it also prevents the warm dry air from entering the room which will lead to this type of thing.
- You might just want to bite the bullet for a dehumidifier. It's $130 well spent. It'll be up to the tenant to keep it emptied and they'll be the ones who take the hit on the power bill, so it's unlikely that it'll cost you much after the initial investment.
- A better window might help a little by lessening the temperature difference on the inside pane, but that's a lot of money/work and I don't know that it would completely fix the issue.

Also, tell them to keep the windowsill clean & dry. Mold is a sign of neglect here.

[Edited on December 7, 2010 at 3:09 PM. Reason : l]

12/7/2010 3:06:17 PM

The condo is on the second floor. It's not too big (~900 sq ft) so the bathroom is relatively nearby, but I don't think this is the cause. I don't think there's much I can do to make them run the vent after showering... its kind of up to them to take care of that. I never had an issue with showers causing that kind of sweating when I lived there.

I don't think the vents are closed. I did notice they installed the air filter backwards and I switched that, so maybe the increased airflow will help. I left them with the DampRid which I think will help quite a bit. I haven't heard from the tenant yet and I told him to let me know how it works out.

I am looking into a dehumidifier as long as it's more of a permanent fixture and less maintenance. I'd like to avoid relying on a tenant to keep it running and emptying it. I'm not sure such a dehumidifier exists.

I was pretty annoyed that they let it sit there and seap into the wood a bit. The wife told me she didn't wipe up the main large window because she couldn't get to it easily because she put a couch in front of it... great.

12/8/2010 11:28:10 PM

A lot of dehumidifiers can be set up with a drain pipe instead of the basin but even then its more likely they will just keep it turned off. I wouldn't worry about it, maybe if you have some spare time I'd paint it with the stuff prevents mold growth. For the moment I'd wipe it with a bleach solution just to CYA and see how it goes over the next week with the temp swings, see if it still happens when temps stabilize a little more.

12/9/2010 9:17:55 PM

Don't listen to those posts. Windows are built not to do that. Water is leaking into those things, and from the looks of that picture your windows thermal seals are broken. They need to be replaced.

12/9/2010 9:30:10 PM

you don't have a leak, you have condensation

houses, commercial buildings, hospitals all deal with condensation issues. even multi-million dollar glass systems in commercial structures can condensate under extreme weather circumstances.

what you want to make sure of is that there's not an air leak somewhere around the perimeter of the windows letting (even a tiny amount of) very cold air in, hitting the warm glass on in the interior causing your condensation problem. also make sure the seals in the jamb, head and sill of the window are still in good shape and forming a solid air barrier.

if you were really interested in the problem you could buy a could of RH sensors with data loggers. if the humidity in the condo is for some reason high this could cause a problem as well.

12/9/2010 10:48:59 PM