- Haven’t seen liquid membranes used much around here either, but I did inspect one job last year where they tried it under concrete tiles. Looked promising at first—nice seamless coverage—but after a couple seasons, there were some adhesion issues where the substrate wasn’t prepped right.
- Traditional synthetic underlayment still seems more forgiving, especially if installers aren’t super meticulous.
- Sealant’s just a band-aid, like you said. Fine for a quick patch, but not a long-term solution.
- If anyone’s considering liquid membrane, I’d say surface prep is everything. Miss a spot and water finds its way in...
- Still leaning toward synthetic underlayment for most tile roofs, especially in wet or variable climates.
I’ve seen way too many folks put their faith in sealant, thinking it’ll keep things dry long-term. Like you said, it’s just a temporary fix—especially under tile, where you’ve got all sorts of movement and moisture sneaking in. I’m partial to synthetic underlayment too, but I’ll admit I’m curious about liquid membranes if the prep is done right. Around here (Pacific Northwest), the weather’s rough on roofs, so any shortcut tends to backfire. Synthetic just seems more forgiving overall, especially for less experienced crews.
Synthetic just seems more forgiving overall, especially for less experienced crews.
I get where you’re coming from. I’ve never trusted sealant to do anything but buy me a little time, and even then it’s iffy. We had a patch job done with some “miracle” sealant under our old concrete tile roof—a couple of winters later, the leak was back, and worse. Ended up costing more to fix the water damage than if we’d just done the underlayment right in the first place.
I’m on a budget, so I always look for what’ll last without costing an arm and a leg down the line. Synthetic underlayment wasn’t much more expensive than felt when we did our re-roof, and it’s held up through some nasty rain and wind. I haven’t tried liquid membrane yet—heard mixed things about how it holds up if there’s any shifting or cracks in the tiles. Anyone actually seen how it does over 5+ years? Or is it just another version of “good until something moves”?
I’m in western Oregon, so constant rain is just part of life here. We had one neighbor who skipped underlayment altogether (not sure what he was thinking) and just relied on overlapping tiles and some kind of heavy-duty sealant between them. Didn’t even make it through two winters—water got in around the edges and started rotting out his sheathing. Not worth the risk.
Curious if anyone’s found a way to keep costs down but still get long-term protection? Is there a trick to installing synthetic that makes it last longer, or is it really all about paying for better prep?
Good question — I’ve worked on a lot of clay tile roofs over the years, and while sealants can buy you some time, they’re rarely a long-term solution, especially if the roof is already aging or prone to leaks.
Your neighbor’s not wrong — upgrading the underlayment is by far the more reliable route if you’re thinking long-term (15–30 years). A high-quality synthetic or double-layered felt underlayment with proper flashing will protect the structure even if the tiles shift or crack over time.
Sealants, on the other hand, can break down under UV and weather exposure, and they can sometimes trap moisture if not applied right.
It’s more upfront cost with underlayment, but way less headache later — especially if you're in an area with heavy rain or freeze-thaw cycles.
- Had to patch a few spots on my tile roof last year.
- Used sealant first—looked fine, but after one winter, leaks came right back.
- Ended up redoing the underlayment in problem areas. No issues since, even with heavy rain.
- Sealant’s just a band-aid, honestly. Underlayment costs more upfront but saved me hassle long-term.
