Mildew smells - To Open a Window or Not

[Hisgirl]

We have a little cottage in the mountains and the main house is air conditioned. We keep it at 74 in the summer and we have no mildew issues.

Outside, there is a free-standing room attached to the decking that is 10 ft by 10 ft and we use it as a 3rd bedroom. It has a window unit and a wall heater but when we are not up here, it has no air conditioning going, unlike the main house.

The little outside room is starting to smell mildewy from being closed up and it being so hot and humid outside (we're in the deep south).

Short of adding its own AC unit (ouch $$$) would we be better off cracking the window and letting fresh air in, even though it's gonna be all humid? I want to talk to a HVAC person about running an intake and Air vent so it can benefit from the main house AC but no one will return my calls.

 

[starry_solo]

Open the Windows

 

[NHdisneylover]

OPen the window wide---better if there are two windows or a door o outside and you an open enough to have a cross breeze---leave it half an hour to allow all the air in the room to leave and new air to come in. Best done in the cooler part of the day (will also be less humid)---very early morning or night time (not right at sunset when mosquitoes would be at their worst, but about an hour after is good).

This is the typical way of handling humidity/mildew in summer in Germany (where very few of us have a/c).

 

[Hisgirl]

Okay, that makes sense, and yes, I forget that yall don't use AC over there. We have screens on all the windows so no issues with skeeters. But what about when we aren't up here? That's the issue. We only come up, or my kids come...every month for long weekends. Do you think keeping the windows open will cut out the mildew smells and prevent it from starting? I'm thinking that makes sense. I sure didn't grow up with AC and we never had a mildew smell but kept the windows open.

 

[NHdisneylover]

Okay, that makes sense, and yes, I forget that yall don't use AC over there. We have screens on all the windows so no issues with skeeters. But what about when we aren't up here? That's the issue. We only come up, or my kids come...every month for long weekends. Do you think keeping the windows open will cut out the mildew smells and prevent it from starting? I'm thinking that makes sense. I sure didn't grow up with AC and we never had a mildew smell but kept the windows open.

I think if you exchange the air, as above, daily when up on the weekend once a month, and also air out any bedding in the room /put pillows, comforter, etc out in the sun for an hour or so, if it isn't raining, that will likely take care of it.
If you have a lot of soft items in there now (stuffed chairs, cardboard boxes storing items, etc)---it might be harder, due to moisture having already built up in those items. If you can get the matress out into the sun once to get it drier as you start, and anything else soft, and replace any cardboard boxes with plastic totes, that would probably help a lot too.

I personally would not recommend leaving a window open or cracked while you are not there. Both becuase of theft issues and also becuase having it open in the heat of the day lets more humidity in. Or at least that is what we are told here (there was a minor mildew issue in the basement of our building and we it turned out someone had been opening the windows at midday which led to the issue.

 

[NotUrsula]

Since the room has power, for times you are not there, I'd add a portable dehumidifier unit with a small drain tube to the outside of the building, powered on a timer. If you run that a couple of hours a night during the warmer months, that should take care of the problem. (Remember to caulk around the tube opening and add a screen tip to the tube itself, to keep bugs out.) You should be able to set that up DIY for around $200, assuming that you don't already own a portable dehumidifier unit. (Look for sales at the big box stores and online.) The power consumption of a medium-sized portable dehumidifier is going to be well less than that of an a/c unit.

Your drain hole is probably going to be 1" diameter or less, low on the wall/floor so that it will gravity-drain, and just large enough to stuff a short length of garden hose tubing through.

 

[Hisgirl]

Since the room has power, for times you are not there, I'd add a portable dehumidifier unit with a small drain tube to the outside of the building, powered on a timer. If you run that a couple of hours a night during the warmer months, that should take care of the problem. (Remember to caulk around the tube opening and add a screen tip to the tube itself, to keep bugs out.) You should be able to set that up DIY for around $200, assuming that you don't already own a portable dehumidifier unit. (Look for sales at the big box stores and online.) The power consumption of a medium-sized portable dehumidifier is going to be well less than that of an a/c unit.

Your drain hole is probably going to be 1" diameter or less, low on the wall/floor so that it will gravity-drain, and just large enough to stuff a short length of garden hose tubing through.

I looked into this and actually bought one, but then all the news came out about fire hazard and I hate leaving anything running while we are out of town. Right now, I have the cross windows open, washing the mattress covers and will leave the windows partially open when we are gone. I'll see if that helps. I'm not so worried about theft. Only thing in there is a bed, dresser, table, and lamp.

 

[mousefan73]

Maybe a granulate dehumidifyer box would help? Its a box that collects moisture.. Not sure the correct name.. Non-electrical.. Not sure how well they work in truly humid climates.. People around here have them in their basesments where things can get damp.

 

[cabanafrau]

I'd invest in something like Damp Rid before I would risk rain getting in and doing more damage with leaving windows open when no one is there.

 

[Wishing on a star]

I would not leave windows open at all, even cracked, when I am not there.
I made the mistake of leaving my car window cracked, maybe 1/2 inch... less than an inch... and one of these southern afternoon storms blew thru, and soaked that side of the car in minutes!!!

I would look at a more permanent solution. Try the local heat and air companies again.

is the roof of this room well ventilated. Could you add some kind of ventilation cap, or even a powered roof ventilation fan/vant?
What type of foundation is this room on.
Is it dry, ventilated, well drained?

Also, about opening the windows when you are there... the humidity and dew point can actually be higher at dawn, and then again at dusk.
It seems like here, if the sun is out, that lowers the humidity during the afternoon. But, of course that is when it is the hottest.
Look at the weather stats on your phone or online for a few days, and look at the % humidity and dew-point.

I too would limit the soft-goods in the room. drapes, carpets, etc...
Mold and humidity can be very bad for one's health, with the molds and dust-mites etc.. (which are kept in check with the lower humidity enjoyed with a good central heat and air unit.)

If the mattress needs replaced at all... Replace it, and immediately put it in a high quality (and not inexpensive) mattress cover.
Do the same with pillows.

We order from one of the good Allergy supply web-sites.

 

[NHdisneylover]

I agree with PPs that leaving the windows cracked while out of the area for a month at a time is likely to let in moisture at some point.

 

[Hisgirl]

Your words about the car did make me shiver. I"ve done that once and once was enough. You are right. No windows left open.

I will be keeping all linens in the main house, pillows included. A mattress cover is a great idea!

Windows have been open airing it out all day and I've gone over every surface with lemon fresh cleaner. Washed the mattress cover. Wish there was a way that didn't involved an electrical machine. We do use the damp rid for sure

 

[DisneyOma]

Bleach what you can - and try to find the source of the mildew odor - is it growing behind the walls, etc? You can air it out, wipe it with scented stuff, but until you kill the mildew, it's still going to smell as soon as you stop wiping and airing. If you won't run a dehumidifier, at least get some of those big jars of dehumidifying crystals to set around the room.

 

[NotUrsula]

I looked into this and actually bought one, but then all the news came out about fire hazard and I hate leaving anything running while we are out of town. Right now, I have the cross windows open, washing the mattress covers and will leave the windows partially open when we are gone. I'll see if that helps. I'm not so worried about theft. Only thing in there is a bed, dresser, table, and lamp.

Yes, well, there is always SOME hazard in any appliance running when no one is home. We do have a dehumidifier installed in our basement laundry room that has an automatic sensor, so that it only runs when the humidity exceeds 60%. It sits on a brick platform with good clearance all around it, and is plugged into a GFCI. We of course are careful to maintain it properly, and maybe it's just luck, but have had this setup for 20 years with no overheating problems. The basement isn't living space, so we are often not down there for days on end.

The other thing that might help your situation is an exhaust fan with an exterior cage. Moving air dries faster than still air, and you can get covered fans that close when the power goes off. (Usually it's a gravity louver cover, so putting a wire cage over the outlet keeps small animals out of it.) These are normally hard-wired in; an electrician would have to install it for you. I'm sure there is probably some way to wire a receiver to let you turn it on remotely if you need to.

 

[ronandannette]

We have a little cottage in the mountains and the main house is air conditioned. We keep it at 74 in the summer and we have no mildew issues.

Outside, there is a free-standing room attached to the decking that is 10 ft by 10 ft and we use it as a 3rd bedroom. It has a window unit and a wall heater but when we are not up here, it has no air conditioning going, unlike the main house.

The little outside room is starting to smell mildewy from being closed up and it being so hot and humid outside (we're in the deep south).

Short of adding its own AC unit (ouch $$$) would we be better off cracking the window and letting fresh air in, even though it's gonna be all humid? I want to talk to a HVAC person about running an intake and Air vent so it can benefit from the main house AC but no one will return my calls.

Get a portable de-humidifier in there stat. Air it out and put some open containers of fresh ground coffee around for a day or two.

 

[cabanafrau]

You can also hang up some mesh bags with activated charcoal to help pull the smell out of the room -- assuming the mildew has already been cleaned up.

If you clean everything you can find and the smell lingers it may actually be a structural issue. Are the gutters clean and the downspouts sending the rain away from the walls?