For high-rise residential projects, Quality Insulation Installation (QII) is not required, but if your project is low-rise and/or attempting to meet LEED for Homes prerequisites, you may not be meeting the requirements of the California Energy Code, Residential Appendix RA, or the ENERGY STAR Thermal Bypass Inspection Checklist.
In the 2019 Energy Code and Residential Appendix RA, QII is a prescriptive measure for single family and low-rise multifamily residential projects, except those located in Climate Zone 7. For most new low-rise multifamily projects, prescriptive requirements may restrict a typical design, thus the performance method is typically pursued as a compliance alternative. This means that one can choose to exclude QII, take an approximately 13.5% energy compliance reduction, and make this up by specifying better building features such as high performance fenestration, a cool roof, or high-efficiency mechanical and domestic hot water equipment. Note that a high-rise residential project cannot take credit for QII, even when incorporating this HERS verification to meet LEED for Homes prerequisites.
Typical exterior wall assemblies (interior to exterior layer) consist of 1-2 layers of 5/8” Type X Gypsum Board, insulation between 2x studs, 1 layer of Type X Exterior Gypsum Sheathing, weather resistive barrier, and exterior cladding or stucco. One detail that is generally missed is the incorporation of exterior rigid insulation or insulated headers.
Per RA 126.96.36.199.9 Special Situations – Window and Door Headers:
(a) All single-member window and door headers shall be insulated to a minimum of R-3 for a 2×4 framing, or equivalent width, and a minimum of R-5 for all other assemblies. Insulation is to be placed between the interior face of the header and inside surface of the interior wall finish.
(b) No header insulation is required for single-member headers that are the same width as the wall, provided that the entire wall has at least R-2 insulation.
In many projects, a single member header with the same width as the wall is used, but exterior continuous insulation is not. Below are two conditions to consider:
Condition 1: Two member header with insulation in between, a manufactured insulated header, or a Structural Insulated Panel (SIP). Note that SIPs are considered an air barrier when properly sealed at top, bottom, sides and all penetration.
Condition 2: Single member header less than the width of the wall with rigid insulation on the interior face.
Regardless of your assembly choice, it is important that envelope details and general language communicate all requirements.
VCA Green offers comprehensive green building consultation, training, and third-party verification services to comply with HERS QII. For more information on how to comply with this and other similar measures, contact Moe Fakih.
Contributing Writer: Barbara G. Gonzalez, Project Manager
Moe Fakih, Principal