Cold Floors and Drafts Caused by an Uninsulated Cantilever in Holmdel, NJ

Thursday, August 13th, 2026 by Michael Gloeckler

Challenge

A homeowner in Holmdel, NJ was experiencing cold floors and drafts on the top floor. The home’s cantilevered bump-out was allowing outside air to infiltrate the open joist bays beneath the floor, creating uncomfortable cold floors and drafts.

Solution

We removed the soffit boards and installed 4-inch-thick SilverGlo rigid foam board with a radiant barrier, blocking each joist bay and sealing the blocks with expanding foam. SilverGlo was also installed against the underside of the floor deck and sealed with expanding foam. The soffit was then reinstalled (the owner will need to repaint it). The top floors are now properly insulated, keeping them comfortable and eliminating drafts.

Project Summary

Products: 4" SilverGlo Rigid Foam Boards with a Radiant Barrier, & ZypFoam Sealant

Back of the home showing the cantilevered bump-out where outside air was infiltrating the top-floor living space.

This entire top floor was allowing cold outside air to seep into the floors. When a cantilever is not properly insulated and air sealed, it can lead to cold floors, drafts, and uncomfortable rooms.

We installed 4-inch-thick SilverGlo rigid foam board with a radiant barrier, blocking each joist bay and sealing the blocks with expanding foam. SilverGlo was also installed against the underside of the floor deck and thoroughly sealed with expanding foam to help prevent air infiltration and improve insulation.

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Cold Floors and Drafts Caused by an Uninsulated Cantilever in Holmdel, NJ

Challenge

Solution

Project Summary

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