Factors to Consider in Calculating Roof Load 
TTML TTML April 30, 2022

Designing the roof doesn't just solely depend on how it looks but it is most especially on its purpose. How will you know that your roof is well designed? These are the factors you need to know when having a roofing project.

Knowing what your roof needs will make you aware of whether the contractor is making a reasonable quotation for your roof project. It isn’t just about the kind of material that was used but also the sizes whether it is under design, overdesigned & or well-designed. It is necessary to have the basic knowledge of the loads that you must consider in the calculation of your roof design and estimation. 

Factors to consider in calculating roof load

1. Live Load

Live loads are considered as loads that aren’t constant but even if these loads aren’t always present on the roof area, they must still be considered. These loads are usually present in the installation, repair & renovation. Most live loads are point loads which means these loads are not constantly distributed on the roof area. These are some examples of roof live loads:

  • Crew/ Roofer - these are the people you have hired to do the roofing job whether it is repaired or newly installed. 
  • Equipment & Tools - these are the materials that the roofers are bringing in while doing the roofing job. 
  • Snow - these should also be considered as it will contribute to the weight your roof carries over time especially when snowfall lasts longer and the snow is piling up on top of the roof. 

>>Related post: What Qualities Do You Need To Become a Roofer?

2. Dead Load 

Dead Loads are the accumulated loads that are present constantly on your roof. These are the load of the roofing material's own weight combined with other construction materials. Mostly, this type of load is evenly distributed in the roof area. These are some examples of roof dead loads:

  • Roof Materials - the material ranges from asphalt shingles to clay material which you can check in our article about How to pick the right roof for your Texas home. 
  • Roof Framing - it could be timber, structural steel, and reinforced concrete, depending on your choice of support. It should also consist of purlins and sag rods to give more stability.
  • Other construction materials - are miscellaneous materials like nails, screws, bolts & nuts.  

>>Related post: The Advantages and Disadvantages of Roofing Materials

3. Wind Load

Wind loads are the wind effect created by a breeze that hits the wall that potentially angles upward. These put pressure on the roof on how it holds to its frame. This load mainly depends on your area and whether it experiences greater wind speed which equates to an increase in uplift load. 

4. Special Roof Load 

Special Roof Loads depend on your future plans for your roof whether you want it to be converted to a green roof or add a solar panel on top of it. This will increase the load your roof carries from adding certain equipment or materials to it. Always make sure that your roof can accommodate the potential weight it will carry. 

>>Related post: How to Pick the Right Roof for Your Texas Home

5. Factor of Safety

The factor of Safety is the ratio of load the material can carry to the actual load as per calculation. The roof design should always bear more loads than its material load. Calculating the factors of safety will consider that the material is not at its maximum capacity and thus should provide a certain safety factor to reduce the risk of failure. Since the factor of safety is ultimate load over allowable load, the value of the factors of safety should always be greater than 1 and its difference is the margin of safety. 


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