I'm looking for some ideas on how to keep my trailer from getting mildew over the cold winter months which was an issue a couple years ago. Tried the chemical dehumidifiers the last couple years but they freeze solid at some point and stay that way till spring, hard to tell if they helped much as each only had maybe 1/2 cup of water, but no mildew. The trailer lives covered outside and has so far been unheated in the winter. Considering a small oil filled electric heater this year.

Never had any mildew problem with mine. It's not covered, not heated but plugged in to keep the batteries charged. The roof vents are open but are covered with Max-Air covers.

We have an 03 Outback. It has spent every winter outside in Michigan. Battery is brought into the house so it can be recharged a few times. Never had any mildew. We do have to keep the refrigerator and freezer doors open.

Why and how is it covered? If you remove the cover you won't get mildew.

Agree with uncovering, mildew comes due to lack of air circulation. I have moisture problems in the warm months not winter.

Had mildew all over the ceiling, walls, and any other hard surface the one year I left the windows cracked and the ceiling vent open a bit, not a fun job to clean up. Makes one think leaving things open was the wrong thing to do. The cover is/was one of the Tyvek Adco jobs.

Winter Mildew Prevention in Cold Northern Climes

17 Replies

Lumpty
Explorer
Aug 25, 2014
One roof vent open under a MaxxAir cover, at least 2 DriEz buckets strategically placed that I will change out about halfway through winter, all cabinets with at least one door open, and uncovered.

Zero issues.
davosfam
Explorer
Aug 25, 2014
We crack a window open, cover the trailer and leave a small portable heater running. The portable heater is set on the lowest setting and comes on when the temp gets below 35 or 40. It automatically shuts off if tipped over.
John_Joey
Explorer
Aug 24, 2014
Up north during the winter it is so arid nothing is needed.

Down south this is what we do when putting a rig away:
close everything
allow the stove flap to open in case of pressure build up
two large buckets of damp rid
two pans of non clumping kitty litter
a few pans of charcoal
crushed newspaper in fridge and cabinets.

Six months later smells like the day we left it.
Padlin
Explorer
Aug 24, 2014
donn0128 wrote:
Mold needs moisture. Are you sure you don't have a leak?

This could be the issue we had. Found half the floor rotted out and soggy early last year, replaced the floor in the fall. No mildew this past winter.

So now which is best, vents open or closed? Heated to just above freezing or not? Chemical dehumidifier or not? Remember, this is for areas that have prolonged freezes.
Dakzuki
Explorer II
Aug 24, 2014
I keep it buttoned up tight with dehumidifier or Dry Z Air. During the winter here it is damp all the time. Venting will just allow moisture in.
stetwood
Explorer
Aug 24, 2014
Northern WIs, temps to -40 degrees. Only have roof vents open. No mildew or mold. It is housed in a shed.
bguy
Explorer
Aug 24, 2014
Padlin wrote:
I'm looking for some ideas on how to keep my trailer from getting mildew over the cold winter months which was an issue a couple years ago. Tried the chemical dehumidifiers the last couple years but they freeze solid at some point and stay that way till spring, hard to tell if they helped much as each only had maybe 1/2 cup of water, but no mildew. The trailer lives covered outside and has so far been unheated in the winter. Considering a small oil filled electric heater this year.

Keep all of your exterior openings shut. Vents, hatches, everything. If you leave something open, every time the temperature drops you trailer takes a long deep breath of winter air.
ScottG
Nomad
Aug 24, 2014
We do just the opposite here. Close everything and cover. I use two Dri-z-airs and end up dumping them about two times during the 6~7 month storage season. Before covering, I would have to dump the DZA'a every month. Covering made a huge difference. (We have never had a leak in this TT)
I've never had a DZA freeze either - don't know how they could since it's a highly concentrated brine solution.
CloudDriver
Explorer
Aug 24, 2014
No cover, roof vents open with Maxxair covers. Eleven years old and no issues with mildew or mold. Only time I noticed condensation on the inside was when I had a leak in the cab over.
CT_WANDERER
Explorer
Aug 24, 2014
I like several other's just left the vents open and no cover on the MH. I was plugged into shore power to keep the batteries charged. Now we just spend the winter in TX, don't have to worry about the MH being in the cold northeast. Gary