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The photos above, sent in by a JLC reader, show great examples of how not to frame a roof with wood I-joists. The bottom flange of the I-joist — the part that is most critical for carrying the bending forces — has no bearing, either at the top or the bottom.It will not take a large load for this roof to fail. What will the failure look like? Most likely, at the upper end the I-joist webs will tear away from the top flanges. At the bottom end, the webs will split and the roof will come down.

Sources of Supply

Wood I-Joists


P.O. Box 2400

White City, OR 97503


Trus Joist MacMillan

P.O. Box 60

Boise, ID 83707



2300 Windy Ridge Pkwy.

Atlanta, GA 30339


Willamette Industries

2550 Progress Way

Woodburn, OR 97071



325 Industrial Dr.

Fernley, NV 89408


Hangers and Connectors

Simpson Strong-Tie

4637 Chabot Dr., Suite 200

Pleasanton, CA 94588


United Steel Products

(USP, Kant-Sag, Silver)

P.O. Box 80

Montgomery, MN 56069

800/328-5934, ext. 235