Good points above. I'd also add a couple things I've learned the hard way:
- Don't just trust the square footage rating alone—if your bathroom has a high ceiling or a big shower area, you might need to bump up to the next fan size. Learned this after installing one that was technically "right" but still left mirrors foggy and walls damp.
- Placement matters more than you'd think. Had a friend who installed his fan way over by the door instead of near the shower... ended up with moisture lingering in all the wrong places. Ideally, put it close to where most steam is generated.
- Also, if you're venting through an attic, make sure your duct run is as short and straight as possible. Every bend or extra foot reduces airflow efficiency significantly. Learned that after crawling around my attic trying to figure out why my fancy new fan wasn't doing its job.
And yeah, insulated ducts are worth every penny—unless you enjoy surprise water drips from above while brushing your teeth...
"Placement matters more than you'd think. Had a friend who installed his fan way over by the door instead of near the shower..."
Good tip, but I'd actually challenge this a bit. I initially thought placing it right above the shower was best too, but after chatting with my contractor, we opted for a spot slightly outside the immediate shower area. Turns out, directly above can sometimes pull cold air down onto you mid-shower—not exactly relaxing... A little offset placement still clears moisture effectively without the chilly surprise.
That's interesting, and it actually reminds me of a job I did a couple years back. The homeowner was convinced the fan had to be directly above the shower stall—like, dead center. I was skeptical, but hey, it's their bathroom, right? Anyway, we installed it exactly where they wanted, and sure enough, a week later I got a call. They said every time they showered, it felt like a mini cold front was blowing down on them. Not exactly the spa experience they were hoping for...
We ended up moving it slightly off-center, closer to the edge of the shower area, and it made a huge difference. Still cleared out the steam just fine, but no more chilly drafts. I think the key is finding that sweet spot—not too far away, but not directly overhead either. Also, something else I've noticed: the type of fan matters almost as much as placement. Some cheaper models just don't move air efficiently, no matter where you put them. Investing in a decent-quality fan with a good CFM rating can really help keep humidity under control.
Another thing people overlook is the ductwork. I've seen bathrooms with perfectly placed fans that still had moisture issues because the ducting was kinked or too long, or vented improperly into an attic space (which is a whole other nightmare...). So yeah, placement is definitely important, but it's just one piece of the puzzle.
Had a similar experience a while back—client insisted on a high-CFM fan thinking it'd solve all their humidity issues. Turns out the ducting was routed through an uninsulated attic space, and condensation kept dripping back down. Re-routed and insulated the ductwork properly, problem solved. It's funny how often the hidden stuff matters more than the obvious choices...
"Turns out the ducting was routed through an uninsulated attic space, and condensation kept dripping back down."
Good catch on the attic insulation issue, but honestly, even well-insulated ducts can struggle if the fan's oversized. Sometimes high-CFM fans pull air through so quickly that moisture doesn't get a chance to vent properly, especially in smaller spaces. I've found pairing a modestly sized fan with passive humidity control methods—like moisture-absorbing plants or clay plaster finishes—often works better long-term...plus it's more eco-friendly.
