Carpokes Porsche Forum

I know that Porsche 944s were galvanized from the factory (and I know from checking that my car doesn't have any glaring rust issues) but should I be concerned about humidity levels? My closed garage sometimes reaches over 70% humidity in the summer. Should I think about getting a dehumidifier or will the car be fine in these conditions? 70% is a bit extreme, it often averages around 50-60% humidity.

Lowering and keeping humidity at at a max of 45-50% in a garage (or anywhere) is always good for cars, tools, structures, people and a lot more. I have always used dehumidifiers.

My 2¢.

Rust never sleeps... I know that from spending 40 winters in New York State, where they put salt on snowy roads.

Humidity is fine, as long as it is not condensation.

Interesting question, do you mind if we ask where you live?

I lived in Miami for a few years, and bought a few portable dehumidifiers for the house and garage. They collected water so fast I ended up creating make-shift drains for them. Otherwise, I had to empty about a gallon an hour... Still, they barely made a dent in the humidity level inside. On the plus side, my 944 spent a few years in that tropical soup, and it hasn't rusted yet.

WillyDaP wrote: Fri Jun 13, 2025 8:02 pm Interesting question, do you mind if we ask where you live?

Central Indiana. Summers can get quite humid but nothing like Miami!

Straight across from you in Nebraska and we get some pretty hairy humidity too and I would say simply, " No worries." I am older than dirt and I have never had any issues with vehicles sitting in a Midwestern garage -- of course most stay there during the Winters. Welcome too, I see you are a fairly new member on Carpokes and folks here are always willing to help, no matter how small or large the concern.

Tom wrote: Fri Jun 13, 2025 8:24 pm I lived in Miami for a few years, and bought a few portable dehumidifiers for the house and garage. They collected water so fast I ended up creating make-shift drains for them. Otherwise, I had to empty about a gallon an hour... Still, they barely made a dent in the humidity level inside. On the plus side, my 944 spent a few years in that tropical soup, and it hasn't rusted yet.

They work better if the space is relatively well-sealed. Hot, humid days in TN can be brutal and dehumidifiers definitely help keep the levels less oppressive.

blueline wrote: Sat Jun 14, 2025 7:00 am They work better if the space is relatively well-sealed. Hot, humid days in TN can be brutal and dehumidifiers definitely help keep the levels less oppressive.

This is an extremely important point. Without digging too deep into the fizziks, humidity 'migrates' readily from high to low. It takes only a very small crack to undo a whole lot of dehumidifying effort in an almost-sealed space.

Another thought is that, while high humidity on its own won't rust out an already dry car, it definitely will impede the drying out process if a car is wet from driving in the rain, washing, etc. The moisture seeps into body panels, contacts, electronics, interiors, etc. and high humidity will keep it damp for longer - not something you want to happen continuously over time.

Add in road salt (yes, I was in southeast MI for almost 20-years beginning in the late 60s, dealing with roadways infested with the rusted quarters, rockers, doors, etc. of living dead vehicles) and you really have a recipe for disaster. Plus, there are other chems and pollutants that are made worse by excessive moisture.

If a vehicle is one that a person wants to take care of long-term and, especially, if one lives in a high humidity part of the world and/or around salt from any source, then a de-humidified well-sealed garage is a plus. It's a little bit of extra insurance and is one that's relatively inexpensive and easy to implement.