Wind-RCI:
New Internet Tool for Calculating Wind Design Loads for Roofs

NRC-IRC recently released an Internet-based tool that simplifies the calculation of roof wind loads, the first, critical step for designing mechanically attached membrane roofs.

Called Wind-RCI , the calculator is based on a six-step procedure developed by the Special Interest Group on Dynamic Evaluation of Roofing Systems (SIGDERS) and researchers from NRC-IRC. That procedure was designed to do calculations based on the National Building Code of Canada (NBC 2005) or the American Society of Civil Engineers guide (ASCE 7-05). While the procedure was an effective aid for calculating wind design loads, it was tedious and time consuming.

Now the six-step procedure has been integrated into Wind-RCI. Developed in cooperation with partners – the Roof Consultants Institute Foundation and the Roofing Contractors Association of British Columbia – the bilingual version based on the NBC 2005 greatly simplifies wind load calculation and reduces the possibility of errors.

Wind-RCI allows users to calculate building wind loads for all Canadian cities by entering the building type (high-rise or low-rise), height and roof dimension, exposure and type. Wind-RCI calculates roof cladding design loads and displays the wind load diagram for the field, perimeter and corner zones of the roof assembly (Figure One).

Wind-RCI is easy to use and greatly simplifies and standardizes the calculation of wind loads on roofs. It has the potential to enhance the interpretation of the code by users, thereby increasing calculation accuracy.

The version based on the NBC 2005 is available at http://irc.nrc-cnrc.gc.ca/bes/prsi/calc_new/rciintro_e.html .

New Phase of SIGDERS Research
In addition to the creation of Wind-RCI, research done under SIGDERS Phases 1, 2, 3 and 4 produced two other significant contributions to improving the performance and reliability of roofs as follows:

  (1)  National Dynamic Wind Uplift Standard
  (2)  A Guide for the Wind Design of Mechanically Attached Flexible Membrane Roofs.

Links for information about these products are available at http://www.sigders.ca.

Now, SIGDERS consortium members have set objectives for Phase 5 research as follows:

Objective One – Monitoring the Wind Performance of Roofs: Three buildings located in a moderate wind zone will be selected and rooftop wind speeds acting on them will be measured and compared to weather data. Instrumentation will be installed and used to measure wind pressure in the field, edge and corner zones of the roofs, fastener forces and membrane deflections. The performance of the roofs will be compared to the performance of similar roofs under wind tunnel testing.

Objective Two – Air Intrusion Quantification of Mechanically Attached Roofing Assemblies: Air intrusion will be measured for mechanically attached roofing systems with and without an air barrier/retarder and for roofing systems with multi-layer insulation arrangements.

Objective Three – Update CSA A123.21-04 Standard to Include Wind Uplift Resistance Evaluation of Fully Bonded Roof System: This research will determine the appropriate test specimen size for evaluating the wind uplift resistance of fully bonded roof systems. It will also evaluate the wind uplift resistance of rigid roofing systems with single-ply membranes, and finally, it will verify the existing CSA load cycle and its applicability to rigid systems.

These three Phase Five objectives are scheduled for completion by August 2010. NRC-IRC is seeking consortium members for Objective Two and more details are provided in the following section (see Energy Rating of Roofing Assemblies: Research Partners Sought).

Specific questions can be directed to Dr. A. Baskaran at (613) 990-3616 or Fax: (613) 998-6802, or e-mail: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it .

order viagra online order viagra online order viagra online free mp3 free downloads