Moisture in the Garage
 

My 64 Pontiac is stored in a wood frame garage with a cement floor that is 55 years old. This winter I noticed there is a considerable amount of "dew" on the underside of the car, lower body, and under the hood.

Does anyone have any suggestions/tips to stop the moisture from settling on the car? Being in Connecticut, the car spends a lot of time (December to March) in the garage.

Thanks
- Frank

I am in Mi. and the trick is to not open any doors when temp or humidity is different from the inside and outside.

I keep a cheap "fan on a stick" running all winter directed towards the underneath of the cars (sweeping motion). Seems to work regarding dew and the constant movement appears to keep any rodents at bay. Not a one to be found and I'm on a (close to) 2 acre semi woody lot (large by Long Island standards). Might want to throw one of those moisture absorbing mini buckets (hardware type store item) in the trunk and interior if you haven't already.

Thanks for the suggestions, I also read online that Damp-Rid pellets work well at keeping the moisture down. I bought a couple containers of it this morning to put in the garage. Someone told me to consider putting a tarp down over the cement floor...has anyone done this? Does it work or does it just trap moisture in the garage? Now that the floor has warmed and the air temp has dropped a few degrees from yesterday's high, the moisture is gone.

Invest into a dehumidifier and plumb the discharge line outside.
My garage was built in '61 and the slab sweats like crazy on humid days.
Most likely pis-poor prep vapor protection under it.
I run my DH 24/7 at 35/40% on low speed and I am amazed at the amount of moisture that it pulls out of the space. Best $100 I even spent.
Controls the issue you're experiencing as well as protects all my garage art :)

Put two 64 pint dehumidifiers in my pole building 35' x 42' 12' side wall pulls lots of water auto set 24/7 everything nice and dry now.

Good luck Gregg

Will the dehumidifier be okay in an unheated garage? This time of the year the temperatures fall below freezing every night and may not get above freezing during the day.

YES mine are in and on -42 last week no heat, they will shut off automatically at a certain temp but check your tank or drain hose daily so any water collected doesn't freeze, they don't run constantly, you can preset the dial when you want the dehumidifier to turn on, mine is set at 75 percent humidity once it reaches the level it turns itself off. I purchased mine from Menards.

Gregg

Dehumidifier worked wonders in my shop (beneath the house, semi-cellar). I keep it set at 65%. No more condensation at all.

As for freezing temps ...my shop never gets that cold (although it gets -15 outside), but I'm pretty sure the water reservoir, pump and outlet hose would freeze solid if it got below freezing. And if the temps came up and it tried to run, the reservoir would I'm sure stay frozen for hours which would probably cause a problem at some point.

However, typically around here when the weather is that cold the humidity is usually pretty low. I use mine mostly during the humid summer months, wet springs and falls.

Money well spent in just the time I save not have to clean rust off the machine tool surfaces.
JohnnyB

You will really notice when spring hits the snow melts, overcast and rainy days will be dry as dry can be.

Gregg

Seal the slab with Muralo or similar product. That is the first line of defense. Otherwise, you are battling an endless flow of moisture from the ground into the building. Also, gas or oil heat will release additional moisture into the building if that is used. If you can reduce the amount introduced then a dehumidifier or diatomaceous earth bags etc. will be able to work a lot better.

Since the moisture is on the underside, it's coming up from the floor and the rest of the air in the garage is ok. Sealing it is the best idea but a quick and easy fix is to pick up a 'blem', 'second', or remnant of roll flooring. Get a piece a little bigger than the car's footprint (7x17). Roll the car out lay it down and put the car back. Problem solved.

^---- Agreed. I use thick plastic tarp as a barrier. That said, at some point I would like to repour the cracked up garage floor, and putting 2" foam insulation and a plastic barrier will be a certainty.

Most humidifiers do not operate below 50 degrees , just use a small fan to blow air under the car on low speed .