*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 catalogueList of Available Wall Assembliesquestion mark iconHow to Use the Effective R Calculator
book iconCanadian Code Requirements for Above Grade Wall Thermal Designnotepad iconUnderstanding the Builder Notes
icon of thermometer with plugWall Thermal Design Performance Literature: Excerpts from the CHBA Manualthumb up iconUnderstanding the Building Science Durability Notes


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

Steering Committee

Alejandra NietoROCKWOOL
Ben HawkenMattamy Homes Limited
BJ YehAPA – The Engineered Wood Association
Bob WilsonR.S. Wilson Building Inspection & Consulting Inc.
Bruce WestCity of Brampton
Christopher McLellanNatural Resources Canada
Cory McCambridgeAPA – The Engineered Wood Association
Dave HendersonBrookfield Homes
David SilburnSAIT Green Building Technologies
Gillian HaleyERA Architects Inc.
Jason ShapardanisEmpire Communities
Jieying WangFPInnovations
John HockmanJLHockman Consulting Inc.
Kelsey SaundersSustainable.TO
Louis PreviteGreat Gulf Homes
Paul SmithMattamy Homes Corporation
Peter BirkbeckIcynene Inc.
Peter CulyerEIFS Council of Canada
Richard KadulskiSolplan Review
Rick GrattonBrookfield Residencial Properties Inc.
Robert MarshallCertainTeed SAINT-GOBAIN
Salvatore CiarloOwens Corning Canada
Silvio PlesciaCanada Mortgage and Housing Corporation
Steve DotyEmpire Communities
Todd RogersCity 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 InitiatorRobert JonkmanCanadian Wood Council
Project LeadMichael LiobuildABILITY Corportation
Project Manager and Publishing ExpertFrancesca CudabuildABILITY Corporation
Builder Lead and Field ExpertAndy OdingBuilding Knowledge Canada
Technical Lead and Building Science ExpertChris TimuskTimusk Consulting, George Brown College
Technical Project AdvisorGord CookeBuilding Knowledge Canada
WUFI Expert PanelistGraham FinchRDH Consulting
WUFI Expert PanelistChris SchumacherRDH Consulting