Mixing underlayments is interesting—did you notice any issues where the felt and synthetic met up? I’ve heard some folks say seams can be a weak point, especially if the porch gets a lot of wind-driven rain.
I had the same concern about the seam where felt and synthetic meet. On my back porch, I overlapped the materials by about 6 inches and used a heavy bead of roofing cement at the joint. So far, even after a couple of nasty storms, no leaks or lifting. I do check it every few months just in case. Honestly, I was surprised it held up as well as it did, but maybe I just got lucky with the install. If you’re careful with the overlap and sealing, it seems to work out fine.
Mixing felt and synthetic isn’t my first choice, but I’ve seen it hold up when folks are careful with overlap and cement, like you did. The real trick is making sure the cement gets full contact—sometimes in colder temps it doesn’t bond as well, and that’s when you get those sneaky leaks. I’ve had a couple jobs where wind-driven rain found its way in right at the seam, but usually only if the overlap was skimpy or the cement was too thin. Sounds like you nailed it, though. Funny how sometimes the “temporary fix” ends up outlasting the rest of the roof...
Mixing materials always makes me a little uneasy, but I get why people do it—sometimes you just use what you’ve got or what’s available at the moment. I’ve patched a couple spots with felt and synthetic together (mostly because the store was out of one or the other), and I’ll admit, if you’re careful with overlap and actually take your time with the cement, it can work. That said, I’m still not totally sold on it for anything long-term, especially in places that see wild weather swings.
The cement’s a biggie. I learned the hard way last fall: did a patch job right before a cold snap hit, and sure enough, the bond just didn’t set right. Next big rain, water found its way in along the seam where I thought I’d been generous with cement. Turns out “generous” isn’t enough if it’s not warm enough outside... lesson learned. Now I warm up the cans inside before using them if temps are borderline. Might sound silly but it makes a difference.
One thing I don’t love about mixing felt and synthetic is how differently they move as temps shift. My roof’s got a pretty shallow pitch and when we had that freak windstorm last March, the synthetic held tight but the felt underneath bunched up in one spot—probably my fault for not nailing it down enough. Either way, that seam was never quite right after.
Still, I agree—sometimes those “temporary” fixes just keep going and going while everything else falls apart around them. My neighbor swears by full synthetic now after he had two leaks in spots where he mixed materials. He says it’s worth the extra upfront cost for peace of mind, but honestly? If you’re meticulous with your overlaps and sealants, you can make almost anything last longer than you’d expect.
I guess for me it comes down to climate—hot and humid here most summers, so stuff moves around more than you’d think. If I ever redo the whole roof again, probably going all synthetic just to avoid these weird compatibility issues down the line... but until then? Patchwork it is.
Man, I hear you on the patchwork life. I’ve Frankensteined so many roofs together with whatever was left in the shed, it’s a miracle some of them held at all. That felt-synthetic combo is like mixing oil and water—works until the weather decides to get creative. Honestly, warming up the cement is a pro move. I once tried to rush a patch in January and ended up with a leaky science experiment. Still, those “temporary” fixes sometimes outlast my patience, so I say you’re doing just fine.
That patchwork approach is honestly relatable—my first winter, I slapped down whatever underlayment I could find, and it was pure chaos trying to seal it up. Still, you kept things standing, and that’s what counts. Sometimes the “temporary” stuff really does surprise you.
