Using I Joists For Roof Rafters

As a structural engineer i have inspected many roofs framed with i joist rafters but very few that have not needed a correction due to the i joist bearing.

Using i joists for roof rafters.

The one that is cut might be a problem. First they made i joist cross cutting jigs from osb scraps and made a few practice cuts. All nails shown in the details above are assumed to be common nails unless otherwise noted. Tj 9001 installation guide for floor and roof framing with tji 110 210 230 360 and 560 joists.

Use single i joist for loads up to 2000 plf double i joists for loads up to 4000 plf filler block not required. Usp994 131 usp connector guide for trus joist. 10d box nails may be substituted for 8d common shown in details. By the end of the class about 90 minutes they had two thirds of the tji roof rafters cut and ready for installation.

Photo 2 shows a view of the other ends of these same i joist rafters and the use of. Yes you can use them for rafters they have to be installed per the manufacturers guidelines. The first thing to understand is how a roof framed with wood i joists differs structurally from a tradi tional stick framed roof. These i joist rafters are on 24 inch 61 cm centers and support plywood roof sheathing and wood shingles.

The diagram provided by bruce is an example of special requirements. While typically not a problem when the roof is flat and the i joists bear perpendicularly on the top plate when the rafters are sloped proper bearing becomes an issue. The manufacturer would need to design the repair. Tj 9510 installation guide for floor and roof framing with tji s31 s33 and s47 joists east canada.

When wood i joists are used as rafters connections at the structural ridge and the tops of exterior walls must be detailed properly. Making top cuts in the i joists to make the short rafters one person held the tji down to the horses while another one made the cut. A framer s guide to the installation process. 9030 floor framing standards guide.