Roofing Geometry: What Homeowners Should Know

We call it “roofing geometry,” but don’t panic – it’s not as complicated as the geometry you learned in school.  Where roofing is concerned, a key element when it comes to initial construction and roof replacements is pitch, which is the steepness of various sections of a roof.

The pitch of a roof on a newly constructed home is something the builder needs to be concerned with.  When it comes to a re-roofing project, the geometry of pitch will be a significant factor in cost for the homeowner and time spent for the roofing crew.

Pitch simply means the amount of vertical rise across a given distance, commonly 12 inches.  You’ll see it written in ways such as 2:12, 5:12; 9:12, 14:12, etc.  The first number tells you how many inches higher the ending point of the measured one-foot section is than its starting point.

A roof’s pitch plays a role in not only the ideal types of roofing materials to use but also in the difficulty and complexity (and therefore cost) of having a new roof installed.  Common terms you might hear when talking to a contractor or roofing specialist include:

• Low pitch: usually roofs up to a 3:12 pitch
• Walkable pitch: up to 6:12 is normally considered “walkable,” but remember that what is walkable to a trained roofer might not be walkable for you
• High pitch: roof pitches of 6:12 and above are generally considered high pitch
• Multi-pitch: as the name implies, some roofs have a variety of pitches throughout the structure

Other roof design aspects to be familiar with

Beyond roof pitch, there are other elements of a roof you should know a little about, because they can affect the process of having a new roof installed.

Valleys

Valleys are the parts of a roof where two planes intersect.  Here is where leaves and debris easily collect and a large volume of rain and melting snow water run.  It’s important that valleys be fitted with sturdy metal pans (troughs) that allow everything to run down them efficiently.

Flared gables

A flared gable is made when the roof’s ridge is wider than its eave.  This is another roof element that can trap water and debris if not built correctly with specifically designed flared-gable treatments.

Dead valleys

A dead valley is created when two sections of the roof meet at their downhill edges, causing a low slope of roofing section that must accommodate a large amount of water.  Metal pans can solve the problem on many roof types.  With metal roofs, dead valleys are usually made more efficient with different types of membranes or other roofing materials.

All this may sound a little confusing, but fortunately your roofing contractor will understand it and be able to work with whatever design elements are present in your roof.

Another piece of good news is that handsome, modern metal roofing is an ideal choice for virtually any roof style.  And the benefits are many including, very long life, extreme durability and resilience, fantastic looks and sun (and heat!) reflection.

You can learn a lot more about today’s metal roofs by calling the experts at Advanced Aluminum.  We specialize in building customized roofing materials for contractors throughout the Lakeland, Fla., area.  Reach us by phone at (863) 648-5787.