How I put in a solar attic fan (and what I’d do differently next time)

Testing a sample in the freezer is a smart move. I wish I’d thought of that before buying three rolls… Lesson learned.

Been there - freezer test is my go-to now. One winter, I tried to unroll a “cold-rated” synthetic and it snapped like a cracker. Marketing claims are a gamble, honestly. I keep a stash of notes too... saves me from repeating mistakes.

Marketing claims are a gamble, honestly. I keep a stash of notes too... saves me from repeating mistakes.

Ha - couldn’t agree more. I swear, half the “cold-rated” stuff out there must be tested in a Florida fridge, not a real winter. I’ve had similar luck with attic fan parts, actually. The first solar fan I installed was supposed to be “all-weather,” but the plastic housing went brittle after two seasons in our Midwest freeze-thaw cycle. Ended up replacing it with a metal one that’s held up much better.

I do the freezer test now for anything plastic or synthetic, especially if it’s going to live in the attic or on the roof. It’s not scientific, but if it cracks after a night next to the ice cream, it’s not making it through January. Sometimes I feel like I’m running my own little consumer lab in the garage.

On the note-taking front, I’ve got a whole notebook with dates, brands, and even sketches of what failed and when. My wife laughs, but it’s saved my bacon more than once - especially when warranty time rolls around and I can’t remember which year I swapped out what.

One thing I wish I’d done differently with my solar attic fan install: double-checking the mounting hardware before climbing up. The kit said “all included,” but the screws were basically decorative. Had to climb down, dig through my stash of proper fasteners, and go back up - twice. Learned my lesson there.

For anyone else tinkering with attic fans (solar or otherwise), don’t trust the box claims and always have backup hardware. And if your attic gets as cold as mine does in February, that “UV-stabilized” plastic might still go snap-crackle-pop by spring.

Funny how much trial and error goes into what should be a straightforward project. At least we get good stories out of it...

I hear you on the plastic housings, but I’ve actually had one “UV-stabilized” fan last six winters up here in northern Minnesota. Maybe it’s luck, or maybe the brand just got it right? I do think the freezer test is clever, but sometimes attic temps swing faster than a freezer can mimic. For me, sealing around the base with a good flashing kit made more difference than the housing material - less water intrusion, less freeze-thaw stress. Hardware quality’s still hit or miss though... I always bring my own screws now, just in case.

- That’s wild - six winters is impressive for any plastic housing, honestly. Maybe the “UV-stabilized” label actually means something for once?
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“sealing around the base with a good flashing kit made more difference than the housing material”

Six winters is no joke for plastic, especially with all the freeze-thaw cycles. I’m with you on the flashing - seen way more leaks from bad installs than from cracked housings. I usually run a bead of sealant under the flashing, but honestly, if the kit fits tight and you’re not in a super rainy spot, sometimes it’s overkill. The hardware thing bugs me too... premium price, bargain-bin screws.

Plastic just doesn’t stand up to winter here, either - six years is about all I get before it starts looking like it’s been through a war. The freeze-thaw is brutal. I’ve had better luck with metal, but even then, if the flashing isn’t done right, you’re chasing leaks every spring. I totally get the frustration with those “premium” kits… why do they always throw in the cheapest screws? Had one snap off halfway in last year. Ended up raiding my own stash just to finish the job.

I’m with you on the sealant. I used to go heavy-handed with it, but honestly, a tight fit and good install seems to matter more than globbing on more goo. Unless you’re in a spot that gets hammered by rain sideways - then maybe it’s worth the mess.

Funny thing, my neighbor thought his fan was leaking because of a crack in the housing, but turns out it was a tiny gap in the flashing from where he rushed the install before a storm rolled in. One tube of roof cement later and he was dry again.

Anyway, nice work getting it up there yourself. These projects always teach you something for next time - usually about what not to buy at the hardware store... or how much patience you actually have for fiddly screws on a hot roof.

Man, I hear you on those “premium” kits - my last one came with screws softer than butter. Ended up using deck screws from my garage just to get through the install. You nailed it about the sealant too... I used to think more was better, but now I just focus on getting everything snug and lined up right. Still, every project seems to teach me a new way to lose my patience (and a few tools) up there. At least you got it done without calling in backup - props for that.

Funny, I had the same issue with the screws - thought I was just being rough, but they really are junk. Deck screws definitely held better for me too. I’m curious, did you have any trouble getting the flashing to sit flat? Mine always seems to want to lift on the corners, probably because my shingles aren’t perfectly even. Wondering if it’s just my roof or if that’s a common hassle.

That’s not just your roof - getting flashing to sit perfectly flat is a pain more often than not, especially on older roofs where the shingles have settled unevenly. I’ve run into this a bunch, particularly after hailstorms when I’m patching things up. Sometimes it’s the shingle thickness, sometimes it’s just the way the decking has warped over time. I’ve found that using a bit of roofing cement under the corners helps keep things down, but you’ve got to be careful not to overdo it or you’ll end up with a mess if you ever need to pull it up again.

One time, I thought I had it nailed (literally and figuratively), but a week later after a heavy rain, I noticed a little drip right at the edge where the flashing was lifting. Turns out, even a tiny gap can let water sneak in, especially if you get wind-driven rain. I’ve started using a small roller to press the flashing down as much as possible before securing it, but honestly, there’s always a bit of wrestling involved. Deck screws are definitely sturdier, but I wish more of these kits came with better hardware to begin with.

Yeah, I hear you on the hardware - why do these kits always come with the flimsiest screws? I’ve had the same issue with flashing not sitting flush, especially where my roof dips a little. Ever tried using butyl tape instead of just cement? I’ve found it’s a bit less messy if you ever need to remove things later, though it doesn’t solve the uneven decking problem. Curious if anyone’s actually had a kit where everything fit right out of the box... because I sure haven’t.

Never had a kit where everything just fit, either - always some weird gap or misaligned hole. I’ve used butyl tape a few times and yeah, way less cleanup if you ever need to pull the fan off. Still, those cheap screws... I just swap ‘em out for stainless now.

That’s been my experience too - never had a kit where everything lines up just right. I always end up having to drill out at least one hole or fudge a bracket to get it to sit flush. I’ve started dry-fitting everything before even thinking about sealant, just to see where the gaps are gonna be. Sometimes you can tweak the flashing a bit, but other times you’re just stuck with a weird gap and have to make it work.

Butyl tape’s a lifesaver for that kind of stuff. I used to use silicone or roofing cement for everything, but cleaning that off later is a nightmare if you ever need to swap out the fan or fix something underneath. With butyl, it peels up pretty clean and you don’t end up gouging your shingles trying to scrape off old goop.

Totally agree on the screws. The ones that come in the box are usually soft as butter - strip out if you even look at ‘em wrong. Stainless is the way to go, especially if you’re in a wet climate or anywhere near salt air. I’ve seen regular screws rust out in under two years on some jobs, and then you’re dealing with leaks around every fastener.

One thing I’d add: check the pitch of your roof against the fan base before you start cutting anything. Some of those kits are made for low-slope roofs and don’t sit right on steeper pitches, so you end up with a big gap at the top or bottom edge. I had to shim one with extra flashing once just to keep water from running straight under it.

If you’re working with asphalt shingles, I always try to tuck the top edge of the flashing under at least two courses, even if it means loosening up more shingles than I want. Makes a huge difference when it rains sideways.

Anyway, seems like every install teaches me something new... usually what not to do next time.

Dry-fitting is such a game changer, seriously. I learned that the hard way after slapping on sealant too soon and realizing half my holes were off by an inch. Butyl tape’s been my go-to for a while now - way easier cleanup if you ever need to redo something, and it doesn’t turn into that cement-like mess. I’ve also run into those “universal” kits that somehow fit nothing right out of the box. Had to bend more than a few brackets just to make things sit flat. Stainless screws are definitely worth the extra couple bucks - nothing like crawling up there two years later just to find a bunch of rusty streaks down your shingles.

- Had the same universal kit headache - nothing’s ever really “universal,” is it?
- I cheaped out on screws once…regretted it when rust stains started showing up after the first winter.
- Butyl tape for sure, way less mess than that sticky goop that never comes off your hands or roof.
- Learned to dry-fit after having to fill in some accidental “bonus” holes - my patch job is still visible if you squint.
- Next time, I’m spending a few bucks more for better brackets and hardware. Way less cursing involved.

Butyl tape for sure, way less mess than that sticky goop that never comes off your hands or roof.

Can’t agree more about butyl tape - saves a ton of cleanup. I’ve seen too many folks try to “make do” with whatever sealant’s in the garage and end up with leaks or a sticky mess. Also, those “universal” kits? Never actually fit right out of the box, especially on older shingles. I always dry-fit everything now, even if it feels like overkill. Learned that lesson after drilling into a rafter once... patching that was not fun.

Also, those “universal” kits? Never actually fit right out of the box, especially on older shingles. I always dry-fit everything now, even if it feels like overkill.

Curious if anyone’s actually had a universal kit line up perfectly, because I sure haven’t. I get why they exist, but it feels like they’re designed for some mythical “average” roof that doesn’t actually exist. My house is from the late 70s, and the shingles are just a bit thicker than what’s standard now, so nothing ever sits flush without some kind of workaround.

On the butyl tape vs. goop debate, I’m a little torn. Butyl is definitely cleaner, but I’ve had it ooze out in the heat and make a mess on the south-facing side. Maybe that’s just a Texas summer thing? The sticky goop (I’m guessing you mean something like roofing mastic) is a pain to clean up, but I’ve noticed it holds up better for me when the temps swing a lot. Anyone else run into butyl getting soft and sliding around, or am I just using the wrong brand?

I’m also wondering about the dry-fit step. I get the logic, but sometimes I feel like it’s just adding another hour to the job. Is it really worth it if you’re working with new shingles and a kit that’s supposed to be “universal”? Or is that just asking for trouble? I’ve skipped it before and gotten lucky, but maybe that’s not the norm.

And about drilling into rafters - been there, done that, patched the hole. Not my proudest moment. Makes me wonder if there’s a trick to finding the sweet spot between rafters without having to pull up half the roof. I’ve tried tapping and measuring, but it’s still kind of a guessing game.

Would love to hear if anyone’s found a sealant that actually comes off your hands easily. I swear, every time I do one of these installs, I’m scrubbing for days...

I’m also wondering about the dry-fit step. I get the logic, but sometimes I feel like it’s just adding another hour to the job. Is it really worth it if you’re working with new shingles and a kit that’s supposed to be “universal”? Or is that just asking for trouble?

Honestly, I think skipping the dry-fit is tempting fate, even with new shingles. I did that once with a “universal” vent kit on my 2018 roof, and the holes still didn’t line up quite right - ended up having to backtrack and patch. Maybe it’s overkill, but I’d rather waste an hour than deal with leaks down the road. As for sealant, I’ve tried a few brands and they all seem to stick around for days... haven’t found a magic solution there either.

I get where you’re coming from - sometimes it feels like half the time on these “simple” jobs is just checking and re-checking stuff. But in my experience, dry-fitting is one of those steps that only feels like a waste until you skip it and something goes sideways. I’ve put in two solar attic fans now, both with “universal” kits, and neither one actually lined up the way the box promised. First time, I figured, hey, new shingles, new kit, what could go wrong? Ended up with a vent that sat a little crooked and had to pull it back up to fix the flashing. Not a fun afternoon.

The second time, I took the extra half hour to dry-fit and mark everything before cutting. Saved myself a headache and probably a few choice words. I guess if you’ve got a dead flat roof and everything’s brand new, maybe you could get away with skipping it... but I wouldn’t bet on it. Especially if you’re in a spot with weird weather - here in the Midwest, one bad seal and you’re looking at water stains by spring.

Sealant is another beast. I’ve tried three or four brands and they all seem to stay sticky forever, especially if you’re working in cooler temps. I usually just plan on letting it sit for a couple days before I call it done. Not sure there’s a magic bullet there - just patience and maybe some painter’s tape to keep the mess down.

If I had to do it again, I’d still dry-fit, even if it feels like overkill. It’s like measuring twice before you cut - nobody likes doing it, but you only regret skipping it when you’re patching holes later.

“one bad seal and you’re looking at water stains by spring.”

That’s the truth. I’ve seen way too many “quick installs” come back to haunt folks after a heavy rain or a late snow melt. Dry-fitting always feels like a pain, but it’s way less hassle than tracking down a slow leak months later. And yeah, sealant in cold weather is just stubborn - sometimes I’ll warm the tubes up in the truck before using them, but even then it’s hit or miss. For what it’s worth, I’ve had better luck with butyl tape under the flashing, especially on older shingles that don’t lay flat anymore. Just my two cents.

“sealant in cold weather is just stubborn - sometimes I’ll warm the tubes up in the truck before using them, but even then it’s hit or miss.”

Yeah, I’ve had mixed results with that too. Ever tried using a heat gun to warm up the area before applying? Not sure if it actually helps or just makes me feel better about it. Also, with butyl tape, do you ever worry about it creeping in the summer heat? My last install, I noticed some ooze after a couple hot days and started second-guessing if I should’ve stuck with just sealant. Curious if you’ve run into that.