finally got our storm shelter checked out and passed with flying colors

We chose untreated cedar too, mostly to keep costs down initially. It's been about four years now, and honestly, it's held up surprisingly well. Just make sure there's decent airflow - stagnant air can cause issues even with cedar's natural properties.

We've had untreated cedar in ours for about six years now, and same experience - holding up great. One thing I'd add is checking corners occasionally...had a bit of dampness sneak in there once, but nothing major. Airflow really does make a difference.

Glad yours is holding up well too. Have you tried using moisture absorbers in those corners? I've found they help a lot with sneaky dampness...especially if ventilation isn't perfect. Might be worth a shot if it becomes a recurring thing.

Moisture absorbers can definitely help, but honestly, I've found they're more of a temporary fix. Had a similar issue in our basement shelter a few years back and tried those moisture boxes - worked fine at first, but eventually the dampness crept back. Ended up installing a small vent fan on a timer, just running it periodically through the day. That did the trick long-term...and wasn't too tricky to set up either. Just something to consider if you notice those absorbers filling up faster than you'd like.

Totally agree about the vent fan - did something similar in our old historic home cellar. Moisture absorbers were okay short-term, but the humidity always crept back, especially after heavy rains. Ended up installing a small exhaust fan with a humidity sensor instead of a timer. It kicks on automatically when things get damp, saves energy, and I don't have to remember to adjust the timer seasonally. Pretty straightforward install too, even in an older structure...just another option if you're looking for something hands-off.