Your roof system is designed to be tough and long-lasting, but it’s not invincible. It can be damaged in several different ways, in fact, which is why it’s important to keep tabs on its condition. You need to be especially wary if your roof starts bowing down the middle; whatever’s causing it can’t be good. Triangle Home Exteriors, the trusted residential roofing company, shares what can cause sagging in your roof system, plus what you can do about it.