Roofs … until it's time to repair or replace one, we don't think much about them. But did you know that the roof over your head is actually part of a system? A roofing system is made up of individual components designed to work together to cover and protect a buildingfrom the outside elements. The four components that make up a roofing system are shingles, underlayment, starter shingles and hip & ridge shingles.