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Community and Q&A

Insulating a steel beam

Jonathan Lawrence CZ 4A New Jersey | Posted in Green Building Techniques on

Martin – have you written an article on insulating a steel beam resting on a foundation wall or does anyone have a detail handy?

I am insulating the foundation wall from the inside and I want to create a thermal break under the beam. I know Dow has a insulated column bearing block product, but they make no mention of using it under beams.

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  1. Tim R | | #1

    You could use a structural fiberglass plate as a thermal break between the concrete and steel. Strongwell makes fiberglass structural shapes.

  2. User avatar GBA Editor
    Martin Holladay | | #2

    The best solution to this problem is to insulate the foundation on the exterior. Other solutions involve compromises.

  3. Jonathan Lawrence CZ 4A New Jersey | | #3

    Thanks Tim and Martin. That Strongwell product looks cool. Structural fiberglass beams - brilliant. They show a picture of a guy carrying a fiberglass beam on his shoulder that would typically be about 700lbs if it were steel. I am going to give them a call on Monday. Maybe I can skip the plate and the steel and instead go with fiberglass beams and posts?

  4. Malcolm Taylor | | #4

    Why not sit it on the sill plate?

  5. User avatar GBA Editor
    Martin Holladay | | #5

    In addition to considering Malcolm's suggestion, you could consider supporting the beam with posts on independent footings, and shortening the beam enough to slip rigid foam between the end of the beam and the foundation walls.

  6. Jonathan Lawrence CZ 4A New Jersey | | #6

    Malcolm - I am not sure why, but I never see steel placed on the sill plate around here. Is there a compression issue? I don't know. It is always set on the top of the foundation wall. The sill place would provide a decent thermal break. Also the steel will be on the same plane as the joists, floor trusses in this case, so that would seem to work. I will ask my engineer about that.

    Martin - I thought about doing a beam pocket that was thermally broken from the foundation wall and I have room to do that. I also thought about just completely decoupling the steel from the wall and using posts on the end (there are other posts in-between the beam ends that are on thermally broken footings, so just the ends of the beams where bridging is an issue). I talked to a few people about that and they were concerned with shear load on windy days, despite the fact that the beams could easily handle the point and distributed loads. A bit beyond my level of comfort and understanding, so I just nodded my head in agreement. Now I know what my Dad kept telling me to major in Engineering in college.

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