*The Effective R Calculator tool is fully optimized for best performance in Google Chrome.

The purpose of this R Value online tool is to provide designers with climate zone-appropriate insulated wall assembly solutions that are easily comparable with national and provincial energy efficiency prescriptive provisions.

Each assembly lists:

  • Effective thermal resistance Reff* for complying with the National Building Code (NBC) for houses and the National Energy Code for Buildings (NECB) for larger buildings
  • Installed R-value for complying with the Ontario Building Code
  • Centre of cavity R-value for complying with the Quebec Construction Code.

*The calculation of effective thermal resistance is performed in compliance with NBC Subsection 9.36.5. of Division B.

Each assembly comes with a climate-specific colour-coded durability assessment, which has been determined considering computer analysis and field experience by building science experts in Canada.

assembled frame wall icon - R Value wall thermal design catalogue List of Available Wall Assemblies question mark icon How to Use the Effective R Calculator
book icon Canadian Code Requirements for Above Grade Wall Thermal Design notepad icon Understanding the Builder Notes
icon of thermometer with plug Wall Thermal Design Performance Literature: Excerpts from the CHBA Manual thumb up icon Understanding the Building Science Durability Notes


Many thanks to the steering committee and project team for making this online tool possible:

Steering Committee

Alejandra Nieto ROCKWOOL
Ben Hawken Mattamy Homes Limited
BJ Yeh APA – The Engineered Wood Association
Bob Wilson R.S. Wilson Building Inspection & Consulting Inc.
Bruce West City of Brampton
Christopher McLellan Natural Resources Canada
Cory McCambridge APA – The Engineered Wood Association
Dave Henderson Brookfield Homes
David Silburn SAIT Green Building Technologies
Gillian Haley ERA Architects Inc.
Jason Shapardanis Empire Communities
Jieying Wang FPInnovations
John Hockman JLHockman Consulting Inc.
Kelsey Saunders Sustainable.TO
Louis Previte Great Gulf Homes
Paul Smith Mattamy Homes Corporation
Peter Birkbeck Icynene Inc.
Peter Culyer EIFS Council of Canada
Richard Kadulski Solplan Review
Rick Gratton Brookfield Residencial Properties Inc.
Robert Marshall CertainTeed SAINT-GOBAIN
Salvatore Ciarlo Owens Corning Canada
Silvio Plescia Canada Mortgage and Housing Corporation
Steve Doty Empire Communities
Todd Rogers City of St. Catharines
To join the committee or to discuss inclusion of more products in the tool, please contact Robert Jonkman – [email protected]


Project Team

Project Initiator Robert Jonkman Canadian Wood Council
Project Lead Michael Lio buildABILITY Corportation
Project Manager and Publishing Expert Francesca Cuda buildABILITY Corporation
Builder Lead and Field Expert Andy Oding Building Knowledge Canada
Technical Lead and Building Science Expert Chris Timusk Timusk Consulting, George Brown College
Technical Project Advisor Gord Cooke Building Knowledge Canada
WUFI Expert Panelist Graham Finch RDH Consulting
WUFI Expert Panelist Chris Schumacher RDH Consulting