Summary
The “Larsen Truss Retrofit” assembly provides a net-zero solution for retrofits. This assembly was approached as if there was only an exterior retrofit being performed on an existing home renovation from the mid-twentieth century, and can be closely compared to constructing the “Fire Resistant Retrofit” assembly, except with an 8” dense pack cellulose cavity insulation instead of exterior insulation strapped.
This video highlights the key features of the assembly.
Advantages:
- Using a more affordable WRB/Air control membrane resulted in cost savings.
- Most materials were able to be found at a common hardware or building supply store.
- The Larsen Truss can be as thin or thick as needed, allowing for more, or less insulation
- Retrofitting an existing home saves waste and new construction costs.
Disadvantages:
- Dense pack cellulose requires installation by a certified installer.
- Installing the flangeless window was more difficult for this mockup than the flanged windows for the other assemblies.
- Utilizing a liquid applied membrane required a drying time before the next steps could be completed.
- It may be difficult to find tradespeople who can or are willing to install this type of assembly in a residential setting.
Image from: p.11, High Performance Wall Assembly Project Summary Report
Taking a deeper dive
Read the full report from SAIT to take a closer look at:
- Wall assembly drawings, sections and details
- Photos of construction
- Constructability and affordability analysis
- Effective thermal resistance calculations
- Comparison charts with other walls in the ENBIX library
Click here to see the energy modelling results for this assembly. The total energy consumption was reduced by 32.55% from the pre-retrofit existing baseline home. Read our blog on the energy modelling of the ENBIX wall library here to understand a bit more of the story.
Watch the recorded LEEP presentation hosted by Retrofit Canada and ENBIX and presented by Stephen Magneron for the LEEP net-zero energy wall guide and case studies, which features the Larsen Truss retrofit here.
The assemblies are also modelled in 3D by Beyond Code and are best viewed from a computer. Click on the links for the 3D models below.
Larsen Truss Retrofit:
- Window Detail
- Exterior Wall – Electrical Penetration Detail
- Exterior Wall – Duct Penetration Detail
- Foundation Detail
- Roof Detail
The rest of the ENBIX wall library is also available as 3D models here.
