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Roof Pitches – A Basic Understanding of Impact With Proposals

Your roof pitch plays a critical role in determining the cost to replace your roof. As the pitch increases, the volume of materials needed increases at an increasing rate. In effect, the cost of the roof goes higher at incrementally increasing rates.

Look at this basic illustration of a roof pitch.

As the pitch increases, more surface area is required to meet the rise of the roof. Look at the angles of various roof pitches here to grasp the change.

The change in the roof pitch adds two additional costs. First are materials. At a 5/12th’s pitch, material requirements to satisfy the rise change are 9% greater than on a flat surface, a 1/1 pitch. At 9/12th’s pitch, it takes 25% more material to cover the additional rise.

The second cost that is directly tied to the roof pitch is labor. A 5/12th’s pitch or lower is considered ‘Walkable’ which means the labor crew does not have to implement additional safety requirements. Once the pitch reaches 6/12th’s (1/2); the crews are required to exercise additional safety protection, specifically fall protection. This additional requirement significantly increases the amount of time to do the work. In effect, on a 7/12th’s pitch, the additional safety standard adds about 20% more time to the labor. At 9/12th’s pitch, compliance requires more than 50% additional time to properly comply with safety and the additional work associated with the extra materials.

So why do roofs have different pitches?

In general, a roof needs at least a 3/12th’s pitch to get rain moving as runoff at a fast enough pace so as not to pool on the roof deck. Depending on where you are located in the country, determines the more common roof pitch for your home. In the Southeast, 5/12th’s is quite common. But up North, higher roof pitches are required in order to reduce and/or prevent snow accumulation which is additional weight for the roof structure. 

Thus, your roof pitch greatly impacts the proposal prices presented to you. The additional cost of materials and labor, especially at the higher pitches, can make your roof replacement much more expensive per square foot than your neighbor’s lower pitched roof.

If you desire a quality proposal from a professional roofer, use an NRCIA member. Contact a professional roofer by filling out this contact form: NRCIA Member Contact for a Proposal