Need advice on replacing an old leaky roof

Yeah, I’ve noticed the same thing - synthetic underlayment just seems to handle weather way better. We had a job last year where it sat exposed for almost a week and didn’t budge. Felt always made me nervous if rain was in the forecast. Guess some upgrades are worth it, even if they’re not “classic.”

Guess some upgrades are worth it, even if they’re not “classic.”

Honestly, I used to be a diehard for the old felt too, but synthetic just keeps proving itself whenever we get caught by surprise weather. If you’re planning the roof replacement, here’s a step-by-step that’s worked for me: First, tear off all the old layers (don’t skip that even if it’s tempting). Next, inspect the decking for any rot or soft spots - patch those before anything else. Then, roll out your synthetic underlayment and make sure you overlap the seams a good 4-6 inches. Fasten with cap nails, not just staples, especially around valleys and edges.

One thing I’m curious about - has anyone tried any of those newer “peel-and-stick” underlayments on a whole roof? I’ve only used them in valleys and ice dam areas, but I’ve heard some folks go full coverage. Wondering if it’s really worth the extra cost or just overkill for most climates...

Tried peel-and-stick across an entire roof once - honestly, it felt like overkill for our climate (mild winters, not much ice). It’s a beast to install in hot weather too. I get the appeal for ice dam zones, but for full coverage? Not convinced it’s worth the premium unless you’re in a really harsh spot. Synthetic underlayment’s been solid for me, and it’s a lot easier to handle.

Tried peel-and-stick across an entire roof once - honestly, it felt like overkill for our climate (mild winters, not much ice). It’s a beast to install in hot weather too.

I hear you on the peel-and-stick being tough in the heat. I remember trying to roll it out on a 90-degree day and it was like wrestling with warm taffy - ended up with more of it stuck to my gloves than the roof at one point.

But about the "overkill" part... do you think there’s any value in using peel-and-stick just in the valleys or around penetrations? I’ve seen a few folks swear by that combo: synthetic underlayment everywhere else, then peel-and-stick where leaks are most likely. Seems like a decent compromise between cost and protection.

Also, have you noticed any difference in noise or insulation with synthetic vs. traditional felt? I haven’t used felt in years but I always wonder if I’m missing something subtle, especially when storms roll through.

I get the logic of skipping full peel-and-stick in mild climates, but honestly, I lean toward using it at least in valleys and around chimneys or skylights. Even without harsh winters, those spots seem to find ways to leak over time.

Seems like a decent compromise between cost and protection.

That’s pretty much how I approach it - targeted use where water is most likely to find a way in. As for underlayment noise, I haven’t noticed a big difference with synthetic versus felt, though some folks claim felt has a bit more sound dampening during heavy rain. Hard to say if it’s enough to matter unless you’re super sensitive to noise.