Case Studies

Insulation Services Case Studies: Cold Cantilever - Vienna, VA

Tuesday, May 14th, 2019 by John LeVan


This home in Vienna, VA has cold floor above cantilevers (overhangs). They were caused by unblocked air flow under the floor suspended over the cantilever and inside the exterior wall.

Comfenergy needed to deploy one of three different methods we use to block the air, attach the thermal barrier to the subfloor and improve the insulating performance of the installed system.


We had originally discuss the use of spray foam with the customer as a method of achieving the goal.  But on the day of installation, the exterior temperatures were very low.  Low temperatures can negatively impact the ability of spray polyurethane foam to cure properly.

The install crew chose to install the equally effective method of using foam board to create an air barrier in the open cavity above the top plate of the wall that holds up the cantilever, and attaching the thermal barrier to the subfloor of the floor of the cantilever itself.

Once the foam board was installed, the fiberglass batt insulation was re-installed to provide additional insulating value.

Project Summary

Consultant: Shayne Sandner

Installation Team Leader: Mike Wilson

About the author
John LeVan is a Mechanical Engineer trained at Columbia University School of Engineering and Applied Science. John also has an advance degree in Operations Management from Cornell University.