Why some roof coatings actually make things worse

- Not sure I totally agree about venting being the main culprit. I’ve lived in the southeast my whole life, and honestly, most of the moisture problems I’ve seen came down to poor installation or just old, leaky roofs - not so much the coatings themselves.
- Had a neighbor put on a reflective coating last summer (asphalt shingle roof, medium pitch). He didn’t change anything else - no extra vents, no new insulation. No issues so far, and his attic is noticeably cooler. Maybe he just got lucky, but it’s not always a disaster.
- I do think you’re right about landscaping, though. I had to rip out a bunch of overgrown azaleas that were basically hugging my crawlspace. Made a huge difference in how dry it stays under there.
- For me, the biggest headache was gutters. Once I added bigger downspouts and made sure water moved away from the house, a lot of my “humidity” problems disappeared.
- I guess my point is, sometimes it’s not the coating or the venting - it’s just basic maintenance stuff getting overlooked. Not saying coatings can’t cause issues, but I wouldn’t blame them for everything.

I guess my point is, sometimes it’s not the coating or the venting - it’s just basic maintenance stuff getting overlooked.

That makes sense. I’ve noticed a lot of folks jump straight to blaming the coating when there’s a leak or moisture, but sometimes it’s just clogged gutters or missing flashing. Out of curiosity, has anyone actually seen a reflective coating cause condensation issues in an attic? Or is that more of a theoretical risk than something that happens in real life? I keep hearing about it, but haven’t run into it myself.

I’ve actually wondered about that too, since I live in a pretty humid area (Gulf Coast). Had a reflective coating put on my old ranch house roof a few years back - mainly to cut down on attic heat. Never saw any new condensation issues, but I did notice the attic stayed cooler, which was nice. From what my roofer said, condensation’s more about poor ventilation or insulation gaps than the coating itself. Maybe in a super airtight house with no venting it could be a problem, but I haven’t seen it firsthand. Usually it’s just blocked soffit vents or something simple like that.

That lines up with what I’ve seen managing properties along the coast - ventilation is usually the real culprit when it comes to attic moisture. Reflective coatings can help with heat, but if the attic can’t breathe, you’re still going to run into problems, coating or not. I had a place out in Mobile where we kept getting these weird water stains on the ceiling. Turned out the soffit vents were clogged with old insulation and a couple bird nests (go figure). Once we cleared those out and added a ridge vent, no more issues.

I get why people worry about coatings trapping moisture, but in practice, I’ve found it’s pretty rare for the coating itself to cause trouble unless something else is already wrong. The only time I’ve seen a coating make things worse was on a flat roof with zero ventilation and a ton of shade - basically a recipe for condensation no matter what you put on top.

Sounds like you did everything right. If your attic’s staying cooler and you’re not seeing new moisture, that’s a win in my book. Sometimes folks overthink these upgrades, but most of the time it just comes down to making sure air can move where it needs to. If anything, I wish more people would check their vents before dropping money on big fixes.

Anyway, glad to hear your experience was positive. Always nice when something actually works as advertised... doesn’t happen as often as we’d like!

I’ve run into this a bunch, especially on older homes where folks try to “fix” a hot attic by slapping on a reflective coating and calling it a day. One place I inspected last year had a nearly new white elastomeric coating, but the homeowner was still complaining about musty smells and even some mold spots on the rafters. Turned out, the attic vents were painted shut (probably from a previous exterior paint job), and there was zero airflow up there. The coating did help with heat, but all that trapped moisture had nowhere to go.

Here’s how I usually break it down for clients:

1. Start with ventilation. Before you even think about coatings, check every vent - soffit, ridge, gable, whatever you’ve got. Make sure they’re open and not blocked by insulation, debris, or, yeah, birds. I’ve seen everything from squirrel nests to wasp hives clogging things up.

2. Look at insulation next. Sometimes people pile it right over the soffit vents without realizing it’s blocking airflow. A quick peek with a flashlight can save a lot of headaches.

3. Only after those two are sorted do I suggest considering coatings. They’re great for reflecting heat, especially in places like the Gulf Coast or Southwest, but they’re not magic. If the attic can’t breathe, you’re just locking in problems.

I do think coatings get a bad rap sometimes - like you said, they rarely cause issues on their own unless something else is off. But I’ve also seen cases where folks blame the coating when really it’s a ventilation or insulation problem that’s been there for years.

One thing I’m still not totally sold on is using heavy-duty waterproof coatings on low-slope roofs in humid climates. I get why people want the extra protection, but if there’s no way for vapor to escape, you’re just asking for condensation and rot. Maybe someone’s had better luck with those than I have.

Anyway, it’s always satisfying when a simple fix like clearing vents solves what looked like a big problem. Makes me wonder how many expensive “repairs” could be avoided if people just checked airflow first...