Need advice on replacing an old leaky roof

If you do go with rigid, just double-check those eaves and flashing details...they’ll bite you later if you don’t.

That’s the part that tripped me up last time. I thought I had the eaves sorted, but after the first big rain, water started sneaking in right where the new insulation met the old fascia. Ended up pulling off a section of soffit just to get a look at what was happening. Turns out, the extra thickness from the rigid board pushed the drip edge out just enough to let water back up under the shingles. Not fun.

What worked for me was running through each transition point—valleys, eaves, dormers—one by one, before even touching the insulation. I made a quick sketch of the roof and marked out every spot where something changed direction or material. It felt a bit overkill at the time, but it saved me from a lot of backtracking.

I get the appeal of blown-in too, especially if you’re not looking to mess with the roofline. But if you’re set on rigid, maybe try a mock-up of the edge detail first? Even cardboard can help you spot weird overlaps before you’re up on a ladder. Just my two cents—those little details always seem to be the ones that come back to haunt you.

I get where you’re coming from about sketching out every transition point, but honestly, I’ve found that sometimes people overthink the details and end up making things more complicated than they need to be. Especially with rigid board—yeah, the thickness can mess with your drip edge, but there are ways to work around it without having to mock up every edge in advance.

“Turns out, the extra thickness from the rigid board pushed the drip edge out just enough to let water back up under the shingles.”

Instead of cardboard mock-ups, I usually just measure twice and use a metal brake to custom-bend my flashing on site. That way I can adjust for any weird buildup right then and there. Plus, if you use a vented nail base or a product designed for over-roof insulation, it can save you a ton of hassle at those tricky eaves.

Blown-in is definitely simpler if you don’t want to fuss with roof details, but rigid has its place—just don’t let the “what-ifs” slow you down too much. Sometimes you just have to get up there and see what you’re dealing with in real time.

- Totally agree that overthinking every transition can slow you down.
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“Instead of cardboard mock-ups, I usually just measure twice and use a metal brake to custom-bend my flashing on site.”

Need Advice On Replacing An Old Leaky Roof

with rigid board, air sealing gets tricky at the eaves if you’re not careful. Ever had issues with wind washing or cold spots after install?

Yeah, that’s a classic headache. I’ve seen a couple jobs where folks skipped taping the seams at the eaves and paid for it later—cold corners in winter, drafty as heck. I usually run a bead of sealant and tape every joint, even if it feels overkill. As for those vented nail bases, I’ve only seen them on one retrofit so far. They seemed solid after two years, but I’d still double-check for critter access... learned that lesson the hard way.

- Always wondered if the extra taping is worth it, but after seeing frost on the inside corners of my buddy’s attic, I’m convinced.
- Anyone else notice those vented nail bases seem to attract squirrels? Maybe it’s just my luck...
- I’d rather over-seal than deal with drafts—cold spots drive me nuts, especially in a “luxury” space.
- Still not sure if rigid board is the best for older homes with weird eaves, though. Anyone try something different and actually like it?