Gutters drain water off of a roof. Water will drain aimlessly from a carport without gutters. Gutters guide the flow to downspouts, where it can be directed away from the building. In the past, gutters were built into a structure, but now they are fastened to roof edges. They can be made from many materials, but vinyl and metal, either steel or aluminum, are most common.

Choose a material

Steel once was the favored metal for gutters, but aluminum largely replaced it because it is cheaper, easier to form and resists rust, which damages steel. Vinyl has also become popular, because it is even more resistant to corrosion and other weather-related contamination. It also is easy for homeowners to install without the help of professionals.

Pick a style

Gutters come in two basic forms, half-round and O GEE, which has a flat side that fits against the roof edge, a flat bottom and a multiple-curved outside that forms a lip at the top. The OG type is more common. Both styles come in 5- or 6-inch widths, but your choice will depend on the size of roof and amount of water to be drained. Either will work on a carport, but the OG is more standard.

Sectional or seamless?

Gutters come in long sections, usually 10 or 12 feet, joined with seams to connect two pieces. Seamless versions also are available in both steel and aluminum. Vinyl only comes in sections. Seamless or continuous metal gutters are built on site; thin sheet metal is formed as it is guided through a simple bending machine. Seamless gutters are created to specific roof lengths, and sections do not have to be connected, creating potential leaks.

Do It Yourself

Seamless gutters must be installed by professionals, but both metal sectional and vinyl guttering can be installed by homeowners. Vinyl is the preferred material for homeowners who want to do it themselves. Vinyl works well on carports, especially those with fiberglass tops or roofs. It is installed with brackets that are nailed or screwed to the sides of the carport; the guttering then snaps into place in those brackets.