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Community and Q&A

Any new materials to protect foundation insulation?

Dick Russell | Posted in Energy Efficiency and Durability on

A past blog here on GBA ran down a list of materials that may be used to protect exterior foam foundation insulation from UV and other physical damage. Are there any new additions to the list I ought to know about?

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  1. Riversong | | #1

    I don't know what was on that list, but I've always used fiberglass-reinforced surface-bonding cement with additional acyrlic modifier and reinforced with a substrate of ½" hardware cloth. It makes an attractive, strong and very durable finish.

    On my current superinsulated project, however, I've eliminated the exterior foundation insulation by using the ThermoMass system, which places up to 4" of XPS in between two 4" whythes of concrete which are structurally connected by 12" oc fiberglass tie rods with the tensile strength of ½" rebar. This offers almost the same dynamic thermal mass benefit of an externally-insulated 8" concrete wall without the challenge of coating the foam and without exposure of foam to insects and the need for termite flashing or inspection gaps. Additionally, this creates a capillary break in the center of the concrete wall. The only thermal bridging is through the steel form ties.

  2. Dan Kolbert | | #2

    I saw those guys at the NESEA conference - thought it looked like a fantastic idea. My current project is a reno on an existing foundation, but am planning on trying that system on my next new construction.

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