Three things you need to know

NRCA maintains several online resources that can assist you with properly designing and specifying roof systems. EnergyWise, Roof Wind Designer and NRCA’s technical library are member benefits many roofing contractors often overlook.

EnergyWise

NRCA’s EnergyWise roof calculator provides a basis for determining the relative energy efficiencies and costs of various low-slope roof system designs.

EnergyWise allows you to input specific roof assembly design information—including a building’s climatic data, heating and cooling appliance types, energy costs and roof dimensions—and graphically construct roof assembly configurations to determine overall R-values and estimated heating and cooling costs. You then can compare these values with baseline energy-efficient values dictated by building or energy codes or energy-efficiency standards.

For roofing professionals considering reroofing options, parameters for a building’s existing roof also can be input to compare possible heating and cooling cost savings that may be possible by increasing a roof assembly’s R-value.

EnergyWise also can be used to verify proper vapor retarder placement as a roof assembly component to prevent condensation.

You can view the results online and generate a detailed report of the specific buildings and roof areas analyzed. Results are saved in the EnergyWise user’s personal account for future reference.

EnergyWise has more than 4,800 registered users who have input more than 11,100 projects. You can access EnergyWise at energywise.nrca.net.

Roof Wind Designer

Roof Wind Designer provides an easy-to-use way to determine roof systems’ design-wind loads for many commonly encountered building types.

Roof Wind Designer design-wind loads are determined using ASCE 7, “Minimum Design Loads and Associated Criteria for Buildings and Other Structures.” ASCE 7 is a widely recognized consensus standard and referenced in and serves as the technical basis for wind load determination in the International Building Code.^®

Roof Wind Designer allows you to choose between ASCE 7’s 2005, 2010 and 2016 editions and uses the following:

• ASCE 7-05’s Method 1—Simplified Method
• ASCE 7-10’s Chapter 30 Envelope Procedure, Part 2: Low-rise Buildings (Simplified)
• ASCE 7-16’s Chapter 30 Envelope Procedure, Part 2: Low-rise Buildings (Simplified) and Part 4: Buildings with 60 ft. < h ≤ 160 ft. (Simplified)

These ASCE 7 design-wind load determination methods are limited to enclosed building types and building height limitations. For buildings outside of these ASCE 7 “simplified” methods, other ASCE 7 analytical procedures apply, which NRCA considers beyond the scope of an online calculator.

With Roof Wind Designer, you can determine design-wind loads using the allowable stress design method for ASCE 7-05 and both the allowable stress and ultimate strength design methods for ASCE 7-10 and ASCE 7-16.

Resulting design-uplift loads are provided for a roof area’s field, perimeter and corner roof zones and roof edges’ design uplift and outward loads. You can view the results online and generate a detailed report of the specific roof areas analyzed. Results also are saved in the Roof Wind Designer user’s personal account for future reference.

Roof Wind Designer has more than 11,400 registered users who have input more than 41,750 projects. You can access Roof Wind Designer at roofwinddesigner.com.

Technical library

NRCA maintains a digital library of roofing-related technical publications, articles and research papers. The library is searchable by author, title, publisher and keyword and contains more than 8,500 titles.

Library content for which NRCA owns a copyright or documents that are in the open public domain (government research papers) are viewable and downloadable directly from nrca.net/technical/library. For other copyrighted documents or documents NRCA does not have permission to distribute, information for obtaining these from the document’s publisher is provided.

Valuable information

I encourage you to make use of these free resources that provide valuable assistance to you as you design and specify roof systems.

Mark S. Graham is NRCA's vice president of technical services.
@MarkGrahamNRCA

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