There is a lot more involved in correct asphalt shingle roofing work than meets the eye, especially where the roof pitch is concerned.
For the shingles installed by even the most skilled roofers to perform correctly, pitch is an essential detail.
What is pitch and why does it matter so much?
To ensure any kind of roof can protect the structure beneath it, roofers must install only the most appropriate materials with roof pitch being one of those critical deciding factors.
What Is Roof Pitch?
Roof pitch, also called slope, is the angle at which the structure rises over its length or its rise over run.
It is a calculation that roofers use to determine two things:
- The angle of the roof slope as it compares to level ground.
- The amount of roofing material needed to cover it.
Documented as a scale, pitch looks like the number of inches a roof angle rises for every foot along the length.
An example of this is a pitch of 4:12 or a rise of 4” in height for every 12” of roof length inward toward the ridge.
What Is The Suggested Pitch For Asphalt Shingles?
Asphalt shingles are one of the most versatile roofing materials used today as they can be used on the widest variety of roofing architecture.
Still, there is a minimum pitch limit that must be met to ensure a proper installation.
For any type of asphalt shingle to perform as designed and keep a roof protected, the lowest recommended pitch is 2:12, with experienced professional roofers and builders recommending 4:12 as the ideal slope.
Higher, steeper pitches are also perfect for asphalt shingles; however, when encountering architecture with a pitch of less than 2:12, roofers will suggest a different roofing material ;as this angle is very close to what is considered a flat roof.
Why Is Roof Pitch So Important With Asphalt Shingles?
As insignificant as this 2” angle allowance may seem, it is a critical calculation referred to by roofers when determining which types of roofing material can be used on a given structure.
Asphalt shingles are designed to overlay starting at the edge of the roof and climbing upward and lose their natural ability to lay flat and watertight affixed only with the nails and adhesives at the top.
With a pitch of less than 2:12, rainwater and snow will lay on the roof, eventually leaking underneath the affixed edges of the shingles, soaking into the underlayment and decking.
The steeper the pitch, the faster that water and snow slide off the shingles via gravity, helping the roof stay drier without the risk of water leaking under the shingle edges.
Always Confirm Pitch Before Installing Asphalt Shingles
Whether looking for a new style of roofing for an existing building or one in the new construction phase, always talk to an experienced contractor about pitch and how it relates to shingles and other types of roof materials.
In most cases, asphalt shingles will be appropriate as a 4:12 pitch is a fairly standard slope, keeping in mind that for structures with lower pitches, shingles will not work.
Qualified and experienced roofers understand the circumstances under which shingles should not be used and will advise accordingly.
As long as the roof architecture has at least a 2:12 pitch, then asphalt shingles and most other types of roofing materials can be used!
