August 3, 2011


The weather is getting cooler (thank goodness) and an old problem has reemerged: Condensation. Nothing gives a vehicle dweller away like foggy windows on a cool morning. No matter how much time you spend making the rest of the car totally stealth, this is the thing that will sink you. Now I’m looking for options. I’m going to be living like this until about October (longer if I can beat the cold) and I don’t want to loose my parking space (again). Here are the obstacles I have to take into consideration (because I will still be driving the car each day).
  • Massachusetts law will not allow me to heavily tint the windows
  • I can’t have anything covering the windows or blocking my view (so no permanent insulation)
  • I can't use a car cover, as I know others have. It would totally give me away.
I have a few ideas that I’m going to start pricing.
  • I could use that heat shrinking window film on the three passenger windows. I’d still be able to see out but it should create enough of a barrier that condensation wouldn’t form. Finding a surface to adhere it to is a slight problem.
  • I could make insulated panels to insert over the windows at night, much like I now put up my neoprene.
The major problem I'm having is with the windshield. I can't think of a good way to cover it temporarily. So I am calling on the collective knowledge of the vagabonding community. This must have come up before. How do you deal with it?


  1. What about a windshield sun shade? That can still be stealth. Lots of people use those.

  2. I never thought of that as being a giveaway for someone being in a car. We actually have a car that condensates on its own, due to a leak in the trunk - it has a lot of moisture as a result.

  3. Try one of these Ash ...

  4. I'm with Anita. Put up a sun shade, and then maybe add insulation to the back of it. That should help, then if that doesn't work, maybe have a peek at Steve's link.

  5. Ash,
    Last year I used this stuff called DampRid. It's a bucket of granules that looks kind of like kitty litter. You just take the top off and set it down in the car and it will absorb moisture. It actually worked really well. bethers

  6. also another plan is to get a vent guard. (goes over the door windows, so you can get ventilation in, yet keeps rain out. (usually lexan plastic, i know you have seen them. anyway, this would allow you to keep the rain out, and yet allow for ventilation inside. Just a thought. also if you have a junkyard, sometimes, you can find a vehicle wrecked that already has them on it, some new double sided sticky tape, and voila, usually below $8-10.00.

  7. Hi Ash.
    It is a real problem.
    I assume you have downloade the d "10 Consecutive Years" book by Craig Robberts to your Kindle. He goes into scientific detail about how you can stop condensation. Unfortunately it involves wrapping the whole living area in pink upholstery foam, so, not very practical, or cheap. His book doesnhave one or two good tips, though.
    Have you tried using a product called Rain X. They make a specific product to spray on the inside of your windows. WD40 also works, but very messy.

    The tubs of anti condensation chemical are good and so is the dehumidifier. If you have a leisure battery, I would also get a 12v fan and keep it running, whatever temperature, in the car.

    I think a combination of all these tips, together with some kind of jnternal cover or insulation on your passenger windows will certainly help, but not eliminate the problem.
    Let us know how you get on.

  8. Howdy, i've had good luck using tea lights...the little candles. My car fairly well vented to start but it'll fog up during the night. I was on a winter trip & lit a tea light & it stayed clear till the candle ran out in the night. i use little candle lanterns for light heat and moisture control. I tent camp a lot & one tea light will cut down summer humidity, help control condensation and will make a noticeable temperature different on a cold night. For stealth you could burn a candle in a vented can.

  9. All these recommendations are good. You probably need to start with a better vehicle.

    If I were me, I would tint the maximum allowed by law in Mass. That means 50% tint on 75-85% windows will yield at most a 37.5% total light transmission, and have labels put between the glass and the window with the percent tint.

    Next you need to insulate your roof, walls and doors, the floor deck would not hurt either. You can use 2" foam board--for the floor deck, cut to fit, with the seams taped. A cheap solution for the walls and ceiling and any gaps is to use "Great Stuff" spray foam over bare metal--you could spray every part of the interior aft of the drivers area and try to put on an inch or two of foam everywhere including the windows. The tint would disguise the fact the windows are foamed over. So that means ripping out the carpet and any panels. Then use a heavy insulated curtain across the front seats.

    You will need some ventilation or a means to absorb moisture. A heat exchanger would make sense, and that is something you could find cheap, I would think, or else you could build one. read up on it.

    I'd also spray the skylight with foam--scraping it off in the spring. You might find a way to hang some attachments to cover this all up with cloth for appearance.

  10. Prolly no longer an issue but anyhoo here goes: To avoid condensation you basically want to attack it in a number of ways. Three ingredients go into its formation. 1. Humidity (you increase it by breathing of course) 2. Temp gradient (you are inside heating the cabin, and the temp outside is cooler. The window glass heats less quickly then air so its still colder than the inside cabin). Notice how it didn't form in summer when hot out? 3. A relatively rough place for droplets to form (normal window glass)

    1. To attack humidity a number of things can be done. You can use a bucket of damprid, but that stuff is nasty. You can use candles - as someone mnetioned, but that is MIGHTY dangerous - don't do that! Venting as you've found is always tricky. One neat trick - run the air before you bed down, but make sure its on "recirculate". That will dehumidify the existing air. Then run the heat without air for a bit - but on outside air, just long enough to make sure the flapper is open to the outside. When you shut off the car - the flapper should stay open to the outside - less humid air and cooler temp.

    2. To attack the temp gradient you can do something like a little fan to exhaust the inside air. Venting will help, but tricky. You can't run the air all night long (which would also assist in reducing humidity). If you are a bit handy - you can build a fan box. While I see that your basically sleeping in the trunk you might be able to find a spot to exhaust air to - like the fender, or into a door.

    3. The roughish surface to which condensate adheres is the easiest to handle. Anti-Fog! All that divers and paintballers and motorcyclists use for helmets to keep fog down - is watered down baby shampoo. Another trick is Rain-X on the inside windows. It should cause condensate to roll off while the baby shampoo forms a thin clear film that is not easy for the condensation to adhere. You can also spit all over the windows LOL or use cheap shaving cream - but don't rinse, just wipe it off.


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