Are Sagging Rafters Dangerous?
I’m remodeling an older home with a rafter style roof. The rafters are 2x4s, spanning 15 feet, and are sagging a lot. Should they be replaced? Is this a dangerous condition, especially considering snow season is coming? — Rick M., Bellingham, WA
Wood is incredibly tough and can take a huge amount of distress before breaking. I recall a restaurant near Banff Canada (bigtime snow country) with exposed rough pole-style rafters that were four- to six-inches in diameter, spanning some 20 feet. They looked like toothpicks. By all accounts these should have failed in the first snow storm. However, it was plain the restaurant had been there many years. The rafters were sagging, but otherwise appeared sound.
Another nice thing about wood: it nearly always provides warning before failure — warning as in excessive sagging, creaking, cracking, etc. I have seen many turn-of-the-century (last century) barns with structural members more resembling pretzels than beams or joists — yet there they stood, taking the load. Certainly, waiting that long before repair is not recommended.