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Insulating at Steel Beam

Good evening,

This question is for a new construction home, climate zone 4A, with north being to the right in the attached PDF. I was planning on using OC spray foam directly under the roof sheathing and in the walls, but I changed my mind during construction after reading accounts of problems with the foam installations, particularly during the winter. I now am now using dense packed cellulose in the walls and using loose fill cellulose on the ceilings.

I have attached a bit of a tricky (non-ideal) detail for everyone's review and comment. My plan is to fill in the web of the W8 steel beam with tapered rigid insulation, foam/seal the rigid to the steel beam, and then provide a 2" bead of foam to the wood members to provide an air seal. The beam will be "warm" in the winter and "cold" in the summer. Unfortunately, the contractor ordered the beam 1.5" too long, so I can only get 1/2" of insulation at the end of the beam adjacent to the exterior wall. I will either foam in this gap or push in a piece of 1/2" rigid insulation. Any thoughts, suggestions, or obvious issues I may be missing?

Thank you to all,

Beam Insulation.pdf32.31 KB
Asked by David Baca
Posted Jan 15, 2013 7:57 PM ET
Edited Jan 15, 2013 7:58 PM ET


1 Answer

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It looks like the steel beam is well insulated -- except, perhaps, at the ends.

One comment: if your contractor ordered the beam 1.5 inch too long, it's within your rights to tell him to cut it shorter -- at his expense.

Answered by Martin Holladay, GBA Advisor
Posted Jan 16, 2013 9:12 AM ET

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