DEVELOPING BEST PRACTICE DETAILS FOR THE INDUSTRY
Location: Canada
Project Type: Industry Education
Key Goals: Envelope Details Best Practices
Services: Air Tightness Construction Detail Modeling
Status: Complete
From 2019 – 2024 CHBA proudly worked with its builder members in ON, SK, AB and BC on the CHBA/ NRCan pilot project, “Affordable, Replicable and Marketable Net Zero Ready Multi Unit Residential Buildings (MURBs)”. As CHBA increases its knowledge dissemination, education and training efforts towards the adoption of the CHBA Net Zero energy standards, Front Porch Design-Build was asked to assist builders and their trades adopt air tight, multi family compartmentalization details that meet fire and sound resistance ratings while reducing air flow, noise and odour between vertically and horizontally stacked units.
Many Net Zero Ready and Net Zero Home Builders have almost perfected the exterior envelope, including insulation, penetration, water protection and air tightness. However, details created in the report specifically address MURB air tight compartmentalization, targeting improved individual unit air tightness at common wall and floor assemblies. The detail guide, one component of the final Project report, addresses an opportunity to improve inter-unit energy, air, sound and noise transfer.
MURBS Report Typology Sample Sheet
MURBS Report Best Practice Sample Sheet
BEST PRACTICE APPROACH SAMPLE
Dwelling Unit to Garage
Where spray applied foam insulation is use to provide the insulation and air barrier it is best practice to provide furring and insulation under the gypsum board membrane to maintain the continuity of the air barrier. This approach allows the spray applied insulation to seal the joints in framing and gypsum board. Additionally the fire rating and STC of the floor assembly remains as per test data. A starter strip of polyethylene at the wall top plate provides a transition between to polyethylene air / vapour barrier at the garage wall and the spray foam insulation at the garage ceiling.
Dwelling Unit to Dwelling Unit
To maintain the continuity of the air barrier at the wall separating the dwelling units, a continuous air barrier membrane should be provided behind walls and landing framing. All joints must be taped with and approved air barrier tape and the membrane must be connected to the ceiling air barrier membrane.
Image: Garage to Dwelling Unit Detail at Floor
BEST PRACTICE APPROACH SAMPLE
To maintain the continuity of the air barrier between units, the best practice is to provide a continuous air barrier membrane at the dwelling unit separation. To ensure continuity of the membrane is maintained it is recommended that membrane starter strips be added to the wall prior to framing the stairs and landing. This can be installed when the gypsum board starter strips are installed to maintain the continuity of the fire rating. Alternatively, a vapour retarder air barrier membrane can be installed full height, prior to stair structure. This will enable drywallers to slide gypsum between the structural stringer and air barrier membrane. Joists and perimeter penetrations of the structural components can then be taped or sealed with approved air barrier tape.
Image: Dwelling Unit Separation at Stair Landing or Winder
