One of the most important measurements when it comes to roofing is the pitch. Not only does the pitch play a vital role in the roof’s efficiency and ability to perform tasks such as draining water from the roof, but it also has a significant impact on the home’s overall appearance.
Here is a look at how this important measurement is calculated and how it affects the home.
Roof Pitch Basics
The pitch of a roof is a measurement used to describe how steep it is. It is a very simple calculation to perform; just determine the number of inches that it rises vertically for every foot that it extends horizontally. For example, a roof rising 8 inches for every 12 inches it extends horizontally is said to have an 8/12 pitch.
A high-pitched roof is one that is above a 6/12 pitch. A high-pitched roof has a very steep slope that can move water off of the roof rapidly to prevent leaking and pooling. This also means that it is more difficult for snow to accumulate on the roof and weigh it down, potentially leading to leaks and structural damage. In addition, a steeper roof creates more attic space that the home’s inhabitants can use for storage or living space.
Roofs with a pitch of less than 3/12 are categorized as low pitch. Low-pitched roofs may not move water as quickly off of them as their higher-pitched counterparts, but they are considered easier and safer to walk across. Flatter roofs are associated with lower installation costs because they require smaller rafters or trusses than a high-pitched roof.
Measuring the Pitch of a Roof
The pitch of a roof on an existing home can be measured from inside the attic. Gather an 18-inch or 24-inch level, a pencil and a tape measure and head to the attic. Measure 12 inches from one end of your level and mark it. Then, place the end of the level along the bottom of one of the rafters in the roof and hold it level. Next, find the 12 inch mark that you made previously on the level and measure vertically directly upward to the underside of the rafter; This indicates the number of inches that your roof rises for 12 inches of horizontal extension.
It is also possible to calculate the pitch of a roof on an existing home from on top of the roof itself, although it is essential to carry this out using full protection equipment and a safety ladder. Therefore, this is a job that is best left to experienced roofing contractors who know how to determine when a roof is safe to walk on and who have the appropriate safety equipment.
For new construction, the pitch can be calculated before the roof is even built. First, you must determine how tall the home stands. Then, take the height of all the floors and add them together, then subtract this figure from the home’s total height to obtain the attic height. The attic’s height represents the estimated rise.
Next, you must determine the span of the house using the distance of the width between the home’s exterior walls. Divide this figure in half to obtain the rafter run. Finally, divide the rise by the run to determine the pitch of the roof.
Understanding Types of Roofs
Here is a look at some of the most popular types of roofs and their general pitch patterns.
- Gable roofs: This is the most common style of roof, with two sloping sides meeting at a top ridge. The end walls have triangular extensions known as gables at the top. This type of roof is the most straightforward when it comes to calculating pitch.
- Flat roofs: A roof that has a pitch of zero is considered a flat roof. However, it is important to keep in mind that many roofs that look like they are flat do have a subtle slope to facilitate water drainage. Like gable roofs, determining the pitch of a flat roof is very simple.
- Mansard roofs: A mansard roof is a four-sided roof that has two slopes per side; the bottom slope is steeper than the top slope.
- Gambrel roofs: A gambrel roof is similar to a gable roof but has more of a barn shape. These roofs feature two sides, and each side contains a shallower slope sitting above a steeper slope.
Contact the Experienced Northern Virginia Roofing Contractors at Adelphia Exteriors
Whether you need a new roof installed, professional roof repair, maintenance or inspections, the experienced Northern Virginia roofing contractors at Adelphia Exteriors are prepared to carry out your project to the highest standards. Contact us online today or call us at (571) 351-1685 to find out more about our services or to request a free roof evaluation.