That’s a good point about moisture meters—they’re handy, but not foolproof. I’ve run into situations where the readings seemed fine, but after pulling up a few shingles, the decking told a different story. Does anyone here feel like certain roof types or climates make these “breathable” coatings more risky? I see way more problems with them in humid areas than dry ones.
I get where you’re coming from about humid climates, but I’ve actually seen “breathable” coatings work out okay in some Gulf Coast installs—at least when the attic ventilation is dialed in and the decking’s in good shape. The problems I’ve noticed seem to pop up more when there’s already hidden moisture or poor airflow under the roof. Sometimes it’s less about the coating itself and more about what’s going on underneath. Maybe it’s just luck, but I haven’t seen as many issues on steep-slope metal roofs, even in muggy weather. Flat roofs though...that’s a different story.
I’ve been down this road with my own place (asphalt shingles, low slope, Houston area), and honestly, I learned the hard way that the prep work matters way more than the coating itself. Here’s what I’d do differently if I had to start over:
First, check for any signs of trapped moisture—dark spots, soft decking, or even a musty smell in the attic. If there’s any doubt, fix that before even thinking about coatings. Next, make sure your attic ventilation is actually working. I thought mine was fine until I realized one of the soffit vents was blocked by insulation... not great.
When it comes to coatings, I get the appeal of “breathable” ones, but if the roof’s already got issues underneath, it’s like putting a band-aid on a leaky pipe. On my neighbor’s flat roof, the coating just made things worse because water was already getting in from somewhere else.
If you’re on a budget like me, I’d say: inspect, repair, ventilate, then coat—always in that order. Otherwise, you might just be covering up a bigger problem.
I get where you’re coming from about prep work being key, but I’d push back a bit on the idea that coatings are just a “band-aid” if there’s any underlying issue. There are some newer elastomeric coatings that can actually help manage minor moisture vapor, especially on low-slope roofs in humid places like Houston. I’ve seen a couple of jobs where the coating bought homeowners a few extra years, even when the decking wasn’t perfect—though yeah, it’s not a fix for major leaks or rot.
On the ventilation side, I’ve noticed that a lot of folks underestimate how much attic airflow matters for shingle life. But sometimes, even with good vents, the Texas sun just cooks everything. In those cases, a reflective coating can drop attic temps by 10-15 degrees (I measured it once with an IR gun), which seemed to slow down shingle curling.
Not saying coatings are magic, but in some situations—especially when full tear-off isn’t in the budget—they can be more than just a cover-up. Just gotta know what you’re working with and set expectations.
That’s interesting about the reflective coatings actually making a difference in attic temps. Did you notice any issues with peeling or bubbling after a couple summers? I’ve heard some coatings can trap moisture if the decking isn’t totally dry, but maybe that’s just with the cheaper stuff.