Car Collecting Questions

Readers Ask This Expert on Collecting Cars and Trucks About Vehicle Storage and the Practicality of ’30s Cars.

Fighting Condensation On Stored Vehicles

I have some questions that rage on among my car and truck collector friends concerning year-round indoor storage of their vehicles.

I live in a northern state with four distinct seasons: Winter (cold with temperatures down to 35 degrees below zero), Spring (rainy, damp, 30- to 40-degree temperature swings from daytime to nighttime), Summer (heat often in the 80s and humidity on occasion approaching 100%), Fall (warm days and cold nights which seems to create moisture and dew inside any enclosed building).

My friends and I store our cars over cement floors with “breathable car covers.” In some cases a few of us paint the floors or lay down a rubber mat under the car to create a shield or barrier between the cold cement and the warmer air under the vehicle.

Still, moisture can be observed sweating off of the cars (due in part to the fact that they stay colder longer as the surrounding air warms up and gives off moisture). And, of course, moisture leads to rust…and so forth.

An “old-timer” collector swears by a design where he has no cement on the floor. He recommends a wooden “barn floor” with a moisture shield between the soil and the wooden floor. I have observed he has no under-car temperature differential with this design.

Of course, temperature control inside any northern storage building would be a great idea but that is not economically possible. The storage buildings are fully insulated but neither heated, air-conditioned nor dehumidified.

Given the predicament posed by northern climates, what are your best recommendations for dealing with moisture and for a storage design inside the barn?

Michael J. Muller Via e-mail

These are questions that plague not only collectors in Northern states, but virtually any state that has distinct seasons. I think I can help. It’s not that I’m a rocket scientist. It’s simply that I’ve been collecting and storing cars for over 25 years, and I’ve encountered the same issues.

Let’s take a look at some of the facts as we know them. First of all, air contains humidity (moisture), which, as you stated, leads to “rust…and so forth” which, as any car collector knows, is a very bad thing. Second, the amount of moisture in the air varies depending on many things including location, weather, temperature, season etc. Third, and most importantly, we don’t want this moisture on our collector cars and trucks!

But how does it get on our vehicles? Why is it that we can park outside on a day when the humidity level is 95% and there won’t be a drop of water on our cars, but park it in a dry garage with a concrete floor, and the next morning the underside of the car is soaking wet?

As you probably know, the answer is condensation, which simply put, is the process by which matter transforms from a gas to a liquid. In this case, it’s the process by which water in the air ends up as water on your car.

The actual process of condensation can get somewhat complicated, but basically it occurs when water vapor in the air is cooled to its “dew point.”

You knew this because you mention the fall season in your state when warm days and cold nights create moisture and dew, and condensation is able to form on your car because the air in your storage facility warms at a greater rate than the surfaces of your car. Where the relatively warm air touches the relatively cool surface of your car, the air is cooled to its “dew point” and the water vapor condenses into water.

The solution, fortunately, is actually quite simple. During the time that the temperature in your storage facility is changing, we must prevent a significant difference between the temperature of the air and the temperature on the surface of your car. If we can prevent this difference, we can prevent condensation and your car will stay dry.

The easiest way to prevent this temperature differential is with a fan, or series of fans that are strategically placed to keep air moving over the surface of your car. If an air mass cannot remain stagnant over your car, it becomes very difficult for the water to condense out of the air, and onto the car.

My experience has shown that the best place to put these fans is at, or just above floor level, aimed underneath the cars. The underside of the car is usually shaded and therefore coolest, creating an ideal environment for condensation. The number and size of fans depends on the number of cars and the humidity level in the air. Usually one fan per car works well. I use the inexpensive oscillating type. You can even put the fans on timers so that they come on very early in the morning and shut off a few hours later, but you’ll find what works best for you with a little experimentation.

This is a pretty simple solution that costs pennies a day to operate.

You also asked about a recommendation for a “storage design” inside a barn. I’m going to have to take you literally in the sense that we are actually talking about a barn, or a building that once was a barn.

You state that the building is insulated but not heated, air-conditioned or dehumidified due to economic concerns. Given today’s energy costs, this is entirely understandable. I would have to revert to my original recommendation to keep the air moving as much as possible, and particularly in strategic areas such as under the cars.

I myself keep at least one of my cars and several antique motorcycles in a building exactly as you describe—it originally was a barn. I made it as airtight as possible and poured a concrete floor. I had some moisture problems during the first year as the temperatures changed with the seasons. After the same careful consideration that you have given to your predicament, I came to the conclusion that fans should work. And they’ve been working perfectly for over 10 years now.

Regarding your question about the type of flooring, I don’t think that there is really much of a difference as long as there is sufficient air circulation.

Naturally this makes the assumption that there is no underlying hydrostatic pressure (moisture or water) underneath your floor of choice. If there were, your idea of painting the floor or laying down a rubber mat might help to reduce the problem. The reason that it’s not working in your case is because the moisture is coming from the air, not the floor. I suspect that the “old timer” that you mention has minimized his problems because he has provided a place for the air to circulate underneath the wooden floor. If he has not, then the wooden floor would not last very long, and you indicate that that is not the case.

I might also point out to you that condensation can be the most damaging in areas where you can’t see it. Your gas tank would be one of these places. Regardless of what anybody else tells you, if your car is being stored for a year or less, always store it with the gas tank filled to the top. Use a good gasoline stabilizer and you won’t have any problems.

You also mention that you use a “breathable car cover.” Some covers are more “breathable” than others. Some are simply a single thin layer of cotton. Others are natural/synthetic flannel-lined heavy materials that may even be suitable for outdoor use.

I prefer the single-layer cotton type for indoor storage. It is by far the most “breathable” and has the added benefit of being the only type that will easily fit into a household washer/dryer.

Using a Vintage Vehicle as a Driver

I’ve decided to buy a vintage car but I’m having trouble deciding just what I should get. My favorite cars are those from the mid to late ’30s—I really like the styling seen in that era. However, I want to drive my collector car, not on a daily basis, but maybe I’d take it to work once or twice a week and definitely use it on the weekends. The problem is, I don’t think a ’30s car is practical for today’s traffic conditions in metropolitan areas. What should I do?

(Editor’s note: This general question was posed by more than one reader.)

I applaud your desire to use a collector car on a regular basis—that’s the way to get the most enjoyment for your buck. However, is it practical to use a car built in the 1930s for this purpose? I believe that the answer is yes, but it depends on how you define “practical.” In the end, I think that there’s a positive answer.

Structurally, these cars are practical for use on today’s roads. They were built to last, at a time when roads were not as improved as they are today. Have you ever looked at the frame of a mid-’30s American car? The frame looks as if it were made out of the same I-beams that support the Empire State Building. And the bodies were made out of steel that is of a much thicker gauge than that used today. Most of them also are perfectly capable of keeping up with today’s highway traffic at legal speeds, and providing a comfortable ride while doing so.

Practicality must also take into account dependability and ease of maintenance, and these cars rank very high in both areas.

Although they are almost eight decades old, they are still modern enough that dependability is not an issue, and they are simple enough that maintenance is minimal and simple. Almost all parts are readily available and relatively inexpensive. With routine maintenance there is no reason that you shouldn’t be able to enjoy a cross-country trip, let alone a cross-town trip.

Last but certainly not least, is the one aspect of practicality in which these cars may suffer. And that is in the important area of safety.

Don’t expect to find air bags, disc brakes, power brakes or ABS. Windshield wipers will likely be vacuum operated so they’ll stop working any time that you step on the gas (when the engine vacuum drops). Electrical systems will do an adequate job at best of lighting your way at night. There was no such thing as a 5 MPH bumper, and the term “crumple zone” would not even exist for another four or five decades. These are all safety issues that we’ve come to take for granted with new cars.

On a personal note, I’d be very curious to see the result of a head-on collision between a 1935 American sedan, and a 2005 American sedan (unoccupied, of course). We might all be a little surprised.

But all is not lost. There are ways to address many of these issues and dramatically improve the safety of a mid1930s car. The best part is that on many of these cars it’s already been done. Since you’ve come right out and asked “What should I do,” I’ll tell you.

You should benefit from the technology which the hot-rod world has provided for us. And not only will you benefit in the area of safety, you’ll also benefit in the areas of performance and convenience.

Many of these cars have already been modified by having the original drivetrain removed and a more modern V-8 drivetrain installed. Often a front subframe is installed which provides a modern front suspension with disc brakes as well as rack-and-pinion or power steering. Along with this transplant comes a 12-volt electrical system which eliminates all of our issues dealing with electricity. Dim lights are a thing of the past, and our windshield wipers will work any time we need them because the motor is operated by electricity instead of vacuum.

Further adding to the issue of practicality are all sorts of comfort and convenience opportunities. It is not uncommon to find air conditioning, power windows, power door locks and stereo systems on these vehicles.

Cars from the mid-1930s are practical in their own right, but when modified in the manner described, their level of practicality almost equals those of our modern daily drivers.

Perhaps the best part is that with relative ease, you can find these cars already modified to any degree that you wish, from mild to wild. And the prices are not likely to give you sticker shock.

Sure, some of these cars that were built by well-known customizers will generally sell for a significant amount of money. But there are plenty of high-quality cars around that were prepared by very competent hot-rodders, mechanics and hobbyists which can be purchased for less than what’s been invested in the car.

In your initial question, you indicated that you like these cars, and that you intend to use yours. Those are the two best reasons to buy a collector car. There is little doubt in my mind that you will find the practicality that you seek.

If you have a question for Steve on anything from selecting the collector car or truck that’s right for you to buying one, operating it or selling it, send it to P.O. Box 6050, Mission Viejo, CA 92690