Continued Affordability The payback period for the cost of installing additional insulation may likely become shorter with the passage of time should energy costs rise. Vapour and air leakage control is crucial for prolonging service life and avoiding expensive repairs to building assemblies. RELATED PUBLICATIONS 2010 National Building Code of Canada (Part 9.36 and Appendix C), National Research Council of Canada 2011 National Energy Code for Buildings, National Research Council of Canada Building Enclosure Design Guide, Homeowners Protection Office (HPO), British Columbia Building Envelope Guide for Houses, Homeowners Protection Office (HPO), British Columbia Canadian Home Builders’ Association Builders’ Manual, Canadian Home Builders’ Association