Figuring out roof support: choosing between rafters and trusses

- Not sure I totally agree about OSB being that much worse. My builder said the new stuff holds up better than it used to, as long as it’s not sitting exposed for days.
- I went with trusses for my place. Didn’t really care about attic space, just wanted it done fast and cheap.
-

“Trusses are great for speed and cost, but if you ever want to use the attic, rafters give you more options.”

Leaks are definitely the bigger headache in my book too. You can have all the ventilation in the world, but if water gets in, you’re still looking at mold and rot - like your neighbor’s plywood roof. I’ve seen both OSB and plywood go bad after a leak, so I wouldn’t say one’s bulletproof. The newer OSB does seem to hold up better than it used to, but if it stays wet for more than a couple days, it can swell up and get soft. Plywood sometimes gives you a little more time before it goes mushy, but not much.

On ventilation - if you’re in a humid area or get big temperature swings, it really does help with preventing condensation and mold. But honestly, if your roof is tight and you stay on top of flashing and sealants, you’ll avoid most of the big problems. I’ve patched more storm-damaged truss roofs than rafter ones, but that’s probably just because they’re more common now.

Anyone ever tried those new synthetic roof decks? Supposedly they’re more water-resistant, but I haven’t seen them in action after a bad storm yet.

I’ve seen a couple of those synthetic decks on new builds, but haven’t had to repair one yet, so I’m curious too. They’re supposed to be more resilient, but I wonder how they actually hold up after a few freeze-thaw cycles or a hailstorm. Anyone notice if they’re easier or harder to work with compared to OSB or plywood?

I get what you’re saying - those synthetic decks sound great on paper, but I’m a bit skeptical too. Haven’t worked with them myself, but I’ve heard mixed things from neighbors. One guy said they were slick to cut, but another mentioned they flexed more than plywood. I’d be curious if anyone’s seen them after a couple winters... freeze-thaw here can be brutal. Good question to bring up.

That’s a solid point about the freeze-thaw cycles - up here, you really can’t ignore that. I’ve only seen one of those synthetic decks up close, and it was on a job last spring. The crew said it was a breeze to cut, but I noticed it did have a different “give” than plywood when you walked on it. Not a ton, but enough that it made me double-check my footing.

From what I’ve heard, the manufacturers say it holds up better against moisture, but I’m with you - real-world winters are a whole different test. I’d be a little nervous to use it on a low-pitch roof, just in case the flexing gets worse with snow load. Still, the idea of not having to worry about rot is tempting.

If you’re weighing rafters vs. trusses, I guess it comes down to what you want out of the space and how much you trust the new materials. It’s cool to see folks questioning the hype and not just jumping on the latest thing.