Your roof frequently deals with a lot of pressure, and it is designed to withstand various loads that could be pushing upward or downward on it. The limit of the load that a roof can handle depends on its specific design. But generally roofs are capable of resisting a few certain types of loads.
In this post, roof repair expert LePage and Sons Roofing LLC discusses the different types of roofing loads and it’s important to consider them during a roof replacement project.
Live Load
Live loads refer to the weight of any temporary objects on the roof. Examples of this type of roofing load are the weight of the people working on the roof and any equipment that they bring to the roof. Typically, a roof can be expected to support a live load of 20 pounds per square foot (psf).
Dead Load
The dead load is the weight of the roof structure itself, including any permanently attached structures or materials on the roof. That said, the roof must be designed to support itself. So if you use heavier roofing material, the load would naturally increase along with it. To give you an idea, the dead load of an asphalt shingle roof with a wood frame is typically 15 psf. Meanwhile, clay-tiled roofing may have a dead load of up to 27 psf.
Uplift Load
The uplift load refers to the upward movement that the wind exerts. Your roof must be able to resist the uplift load. Typically, an uplift load limit has a maximum wind speed of approximately 90 miles per hour, and the expected load is about 20 psf.
Calculating Load
In order to determine the appropriate roof framing members for a building, your roofing contractor must first determine the loads that your roof will have to bear, both dead and live. They would have to check the minimum load-bearing requirements in your local building code. The code book usually indicates the minimum load limits and deflection limit. Apart from the dead and live loads that your roof needs to support, your roofer would also have to determine the span of the roof’s rafters. Then, they would have to consult span tables to figure out the lumber dimensions and wood species that are suitable for your rafters.
Slope Correction
In load limit calculations, it is assumed that loads are pushing downward uniformly on the roof’s horizontal surface area. On a roof with a steep slope, more weight tends to push downward on a relatively smaller horizontal surface. That said, your roofer should take this difference into account and adjust the roof’s load limits accordingly.
LePage and Sons Roofing LLC has several years of experience in handling residential roofing projects. We carry out a range of tasks including roof installation, replacement, repair and more. Rest assured that our team is dedicated to providing top-notch services and excellent customer service. To request a roof estimate, you can call us at (508) 295-6483 or fill out our contact form.