Insulating wood I-joists with Roxul
O.K., to repeat, I’m building a 1-story house in Zone 4C. Builder is using wood I-joists 16″ O.C. for the floor. After considerable thought and reading, including comments by Dana Dorsett and research by Washington State University, I decided that an open crawl space would work for me. However, I have insisted that we use good insulation: R-24 (commercial size) stone wool batts by Roxul for the floor insulation. This comes in 16.25″ widths. My builder says, Fine, but how are we going to shove them past the flanges at the top of the I-joist so that they’re snug against the floor? And would this cause voids? Good question. The most minimal TJI’s, with 1 3/4″ flanges at the top, would have 14.25″ between them at 16″ O.C. So I sent an email to Roxul in Ontario. They were useless. The girl that answered me scarcely knew what an I-joist was. Her salespeople, she said, had never heard of people insulating I-joists. And so I am asking the GBA community, which I guess means the long-suffering Martin. Does anyone have experience insulating wood I-joists with Roxul mineral wool batts?
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