I need some opinions on which product works best for underlay under a metal roof. 15lb felt or the new synthetic stuff. Any opinions are welcome lets be nice though. I know the synthetic underlays are a lot more money, but are they that much better.
I would say with honesty that only SOME of the synthetics are better than felt, and I haven't tried all of them. Feltex lays very good along with Shinglemate from GAF and Certainteed's Roofers Select. The cheapo 15 lb felt is almost useless.