The International Cessna 170 Association

I am wondering what, if any, suggestions there may be for excess moisture in our hangars. I recall a number of times in Texas where the roof of my hangar would sweat due to condensation. It usually was gone in a day or so. I was in a friends hangar yesterday, at a different airport from mine, and noticed his plane's windows were fogged up due to moisture. This morning I stopped by my hangar to drop off something and everything in my hangar was damp or dripping. My plane's windows are all fogged up, the exterior is totally wet and even tools in my tool boxes are wet I know its not good for any of that to be that wet. We have had several days of light rain, but just wondering if I am in for any unusual problems other than tools rusting. I turned on a fan so it could blow onto the plane, but don't know if that is of any value or not.
Thoughts?

I'm curious as well Frank. High humidity mornings like we had today cause my hanger to drip the condensed moisture from the roof. I have wanted to have it sprayed with foam insulation for several years but that hasn't happened yet.

Paul, I had that happen at several hangars I had in TX, but never did find as much on the plane and certainly not on all my wrenches, etc. in my roll around tool box. There probably isn't much that can be done short of spraying the roof and possibly the walls as you mentioned. Maybe someone will know something?

Hangars will "sweat" if there is moisture inside the bldg. and the outside air temp is sufficiently cold to condense the moisture. It sounds as if both you guys have a problem worth addressing.
If you have a dirt floor...that's a problem.
If you have a non-vented, fossil-fuel-burning hangar heater...that's a problem.
If you're like a friend of mine who thought the central drain in the concrete floor of his hangar was meant to drain the hangar after he washed his airplane inside the hangar...that's a problem. Don't wash anything inside the hangar. (Does your hangar have a bathroom/urinal/shower/wash-tub? Bad for humidity!)

If you insulate the internal walls of your hangar, but do nothing about the humidity inside the hangar... that's still a problem, because while you may no longer observe the moisture condensing on the sheet metal because you've hidden it with insulation.... it's still attacking everything inside the hangar and it may also contribute to early rust/perforation of your hangar's roof and walls as any condensation may become trapped between the insulation and the sheet metal. It may also contribute to mold if the roof isn't sufficiently pitched.

Are the doors/windows weather-strip sealed? Is the hangar made of corrugated metal or "R-panel" type sheet metal...?? ...and is it not sealed at the bottom and top of the corrugations? If so, then outside humidity is entering the hangar thru the 1" or so openings at top/bottom/ends of the sheet metal at the corrugations. You basically have an open hangar! You must seal those openings with rubber or foam.

A dirt floor is a major contributor to internal humidity. The floor must have a membrane or a membrane covered with concrete, or moisture will be a continual problem.

Move to Del Rio, TX. All you will have in your hangar is DUST!

The only way I know to keep high humidity from condensing inside a hangar is to have a totally sealed and insulated building. That isn't going to happen in a municipal T-hangar with gaps all over the building, no positive seals around the doors, and a wet floor or with water standing on the floor. The best you can do is vent the wet air out as quickly as possible once the temp goes back up above the dew-point. A wind-powered turbine roof vent works by taking moist air out the top or wall louvers on ends of the building in-line with prevailing winds. Wall louvers aren't very effective in a nested T-hangar building.

There is no good solution! Use lots of Corrosion-X or ACF-50.

Jughead- I'll take dust any day!

As Richard correctly pointed out, hangars at municipal airports will most likely never be properly sealed. At our airport we have hangars of 4 vintages. Mine is a second generation one where there is a gap under the sliding doors with a vent cap running the entire width (left to right) of the hangar. There is no way to seal it. However I talked to several hangar occupants this afternoon who have hangars in all four age groups including the newest ones with good bi-fold doors and all of them are super wet today. We have had lots of rain (don't be jealous George) and the temperature has been in the high 50's - low 60's the past several days so we will just have to live with it until some of that eventual dry TX air moves up here, which it will. Its obvious there was no vapor barrier prior to pouring the concrete floors. Best thing must be to go fly as soon as possible and fly out the moisture

There is so much moisture in the hangers at Quakertown, Pa. that last week several could not fly their airplanes as they were frozen in ice to the floor. And they are charge $450 a month regardless.

My Port-A-Port hangar at Grand Prairie, TX, KGPM, was built on top of a sloping asphalt tiedown area. When it rained, water would run thru the hangar at an unimpeded rate which depended only on the strength of the storm. The previous owner simply poured a 2" slab of concrete on top of the asphalt inside of the hangar and levelled it off with respect to the lower 2" frame of the hangar. For $1200 about 10 years ago, that totally eliminated the problem and the hangar is bone dry except on those few high humidity days with condensation.

If the owner of wet rental hangars would allow renters to do the same and deduct the cost from their monthly rental until paid off, that would benefit both the owner and renter.

hilltop170 wrote:If the owner of wet rental hangars would allow renters to do the same and deduct the cost from their monthly rental until paid off, that would benefit both the owner and renter.

The airport authority will not allow any modifications to their hanger. And they don't have to. You have to pay your hanger fee no matter if you can use your airplane or not. They don't care. They collect every month. They don't have any empty hangers either.

I hear you Bruce. The airport at Lebanon, TN is having a major runway project where they will remove an existing rise in the middle of the runway. Airport closure expected to be 90 days! Our runway at Murfreesboro is having taxiway changes (no more angled/high speed taxiway exits) which is going to close our runway for 35 nights (6 pm-6 am). A runway extension is also planned for July with no closures, just a displaced threshold, but once completed the runway and taxiway gets all new asphalt which will close the airport totally for an estimated 22 days Neither airport is making any concessions to tenants. FBO's will be impacted pretty heavily.

Sheesh! You guys from the SOUTH don't even begin to understand moisture until you've had to deal with frost coming out of the ground!

About the only thing we can do when spring rolls around is open the bifold door so you've got ventilation on the sides and under the door boot. Yep, you end up with dust and other crap in the hangar but it's about the only remedy to the moisture from the 'sweat' off the floor to evaportate.

(For what it's worth I did get to fly yesterday without wearing a jacket!! Spring in MN - yeah)

It's been raining for 3 days here, so I went on an investigation. Looked at some T-Hangars - all had water in the first 3 feet of doorways. Most had water in the rear, coming from backside or neighboring hangar. One had the concrete curb built around back.. Sure enough planes had condensate all over them. Another potential buyer and I worked on ideas to fix the problem - gutters, french drains, groove concrete between door tracks, roof over hang. Went into 2 Airport Maintenance Hangars - floors sweating, water streams running from door to drains - moisture on Citation. At this point I took off to my hangar - thankful to find it dry. I feel bad for plane owners having to deal with this.

I turned on two fans and directed them on either side of my plane. It did remove the moisture on the windows and most on the plane. The following day my hangar and plane were dry. I doubt the fans are the reason. Probably a change in humidity and/or temperature.

My "hanger" is wetter than most on certain days, and sometimes there is little difference. And some days it is dryer than others and that is a fact.