Forum Title: Lo Slope Roofs!
In another thread we mentioned the minimum slope for slate would be 6/12. True. (On another forum.) Now, let's talk about real life experiences and observations. Here, we have many, many examples of historic properties that have slate on slopes of 2/12 or 3/12. Everywhere! There is evidence that felt was used when the roofs were installed back in the late 1800?s and early 1900?s on these jobs. All were done with a minimum of 15# felt and 2? headlaps. On planks. I've repaired or replaced many of them and now will shed some light on my personal findings. This has nothing to do with rules, books, or spec sheets. Just life. The vast majority of these lo-slope slate roof are on porches. One in 2000 might have copper nails. I seldom see that. Primarily because of the nail used, belI've it or not. Keep reading. Quite often I get a repair call and find evidence of one or two leaks. Not water pouring in like you would expect. I find that the nails have rusted into powder and the slates have slid out. If the leak hasn?t been going on for years, there is no wood damage and a simple repair is all That's needed. Sometimes, I find the whole roof is sliding off and the owners Can't or won?t replace it now. They will pay for me to slide all the un-nailed slate back into place. Amazingly, they stay in place for many years without leaking again. In each of these cases, the underlay is a black powdery dust that used to be felt, or just wood. There is also another factor that really causes most leaks on these porches. They are used like scaffolding by painters, handymen, and the HO?s to paint and maintain the homes, or whatever! Some folks around here even set chairs and lounges on the slate to sunbathe! Lots of broken slate and the resultant leaks there! Real life tells me this. Slate breathes, and you can look under the slate from gable to gable if you want proof. Planks are the best sheathing. Even if they get damp from the lack of headlap, they?ll dry out in a hurry and still go 100+ years. Plywood won?t. If they get really wet and keep getting wet, they?ll rot out in a few years from a single leak. The damage will be confined to the area of the leak too. A single 16? plank may be the total wood repair. Not so with plywood. 1/2 sheet minimum there!
Post By: ANA SANDOVAL (Murfreesboro, TN), 02/23/2018