21-0527 Muhlenberg College Responsible Material Sourcing for FSC SIPs


Post, 1 Imperative 6: Responsible Materials, Requirement 2: 50% of wood products, by cost or volume, must be FSC, salvaged, or harvested on site either for the purpose of clearing the area for construction or to restore or maintain the continued ecological function of the site. 

Narrative: Our project is using structurally insulated panels (SIPs) for the building roof. Based on experience and due diligence, FSC certified SIP OSB is not currently available on the market. The team has coordinated with the SIP manufacturer for this project, and they are unable to get SIP grade OSB that is FSC certified. They are also unaware of any SIP manufacturer offering it. There are currently two manufacturers who produce SIP grade OSB (which is different from sheathing grade OSB) and neither of them offer FSC certified products. 

Since it is anticipated the SIP cost and volume will be more than 50% of the total wood on the project, meeting the requirements of this Imperative may be difficult. 

SIPs were chosen for the following reasons: 

  • They allow for steel roof decking to be eliminated, thereby reducing the building’s embodied carbon • Factory manufacturing reduces construction waste 
  • Factory manufacturing provides a high level of quality control, which reduces chances of installation errors and air gaps or defects 
  • SIPs provide the required thermal insulation with very limited risk of air leakage. 
  • Factory manufacturing speeds up construction times. 

Murus was chosen as the SIP manufacturer because they are local. They are located in Mansfield, PA, which is approximately 180 miles from the project site. 

Additionally, the project team plans to send advocacy letters to the OSB manufacturers with the hope that the market will shift to manufacturing FSC certified products. 

Given the benefits of SIPs and the unavailability of FSC grade SIPs, the team feels we are demonstrating intent compliance with the Imperative. Additionally, we have reviewed the public Dialogue and have confirmed that our requests have not already been addressed in the Dialogue.


Based on the information provided, ILFI cannot grant an allowance to fall below the requirement that 50% of the wood by cost or volume, must be FSC, salvaged, or harvested on-site. FSC SIPs have been used on a number of certified projects, including the Nature Labs at Phipps in Pittsburgh and the Perkins SEED Classroom in Seattle. Additionally, the project may be able to work with a SIP manufacturer to source FSC wood and achieve FSC chain of custody. The project team may also want to consider an alternative envelope scheme that does not use SIPs if FSC panels cannot be located.

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