The prescriptive residential energy code requirements found in the 2009, 2012 and 2015 International Residential Code (IRC) include requirements for continuous insulation at foundations (Table N1102.1/R402.1) in several climate zones. This research report discusses the issue of cantilevered sill plates supporting metal plate connected wood trusses installed parallel and perpendicular to the foundation walls where there is a potential for discontinuous planes between the exterior wall above the sill plate and the foundation insulation planes. An example is shown in Figure 1. This report is based on the following assumptions:
- Exterior wall sheathing is any thickness to align the exterior face of the sheathing with the exterior face of the sheathing below.
- Basement continuous insulation is installed on the exterior of the foundation and does not exceed 2".
- Floor system is bottom chord bearing metal plate connected wood trusses.
- The sill plate does not overhang the foundation by more than 19/16".
It is important that all structural, energy, and durability requirements be taken into account.
This legacy SBCA Research Report represents information and code requirements current as of the publication date shown. However, codes and standards change periodically. The user is encouraged to verify the referenced information is still current and conforms to current code requirements.
Feeling inspired? Share these insights on social.
