15 Roofing Terms Every Homeowner Should Know


Today, we’re going to break down some of the most common roofing terms. Some of them can be a bit tricky to keep straight. We hope this glossary will help you better understand what your roofer is talking about the next time you need to repair or replace your roof. It should also help make shopping for and buying a roof a bit more straightforward.



The deck (also called sheathing) is the base of a roof. Roofing materials are built over this surface, which is often made of solid or engineered wood.



The eaves are the part of the roof that hangs over the edge of a home’s exterior walls, located just above the gutters.


Fire Rating

Each roofing system is given a fire rating, with Class “A” being the most fire resistant, Class “B” being moderately fire resistant, and Class “C” being lightly fire resistant.



Flashing is installed around obtrusions in your roof and along edges. Strips of metal prevent leaking around chimneys, vent pipes, skylights, solar tubes, and at other intersections or projections throughout the roof.



This is the angle formed where two sloping roof planes intersect. The angle runs from the ridge to the eaves.



A penetration is anything that protrudes from the roof, such as a vent pipe or chimney.



Roof pitch is the ratio of the roof’s vertical rise to its span, often expressed as a fraction.



The ridge is the highest point on a roof (the peak), where two segments meet to form a horizontal edge.



The rise is the vertical distance from the eaves to the ridge.



The run is equal to half the span. It’s the horizontal distance from the point directly beneath the ridge to the eaves.  



The slope is the degree of incline, expressed as the ratio of the number of inches of vertical rise to 12 inches of horizontal run.



The span is the horizontal distance from the eaves on one side of the roof to the eaves on the opposite side.



A square is a common roofing measurement and is equal to 100 square feet.



The underlayment is installed beneath the shingles in a roofing system to provide an extra layer of protection against severe weather to prevent water damage.



Valleys are the lowest points of a roof where two downward sloping segments meet.


For a comprehensive glossary of roofing terms, see Owens Corning’s Roofing Glossary.


Hedrick Construction is an Owens Corning Platinum Preferred Contractor. Reach out with any roofing needs or concerns you have in the Ames or Des Moines area.