Framing a Two-Pitch I-Joist Roof

After setting the gable end rafter for the lower section of roof, the author measured down from the main ridge to the point of intersection.

The wall was scribed to match the gable rafter's slope.

After the scribed line was transferred to the outboard face of the wall, the top of the wall was trimmed to match the slope of the gable rafter.

The scrap piece of wall was pulled off.

Pieces of OSB braced the slope transition.

Rafters were attached at the wall plate with structural screws.

Short pieces of I-joist were used to block between all the rafters.

The built-out wall I-joists were mainly intended to provide an insulation cavity.

The built-out wall I-joists also help address wind uplift because they are screwed into both the wall and the roof rafters.

A second rafter was set at the other end of the roof.

A layout line was snapped between the two rafters to guide placement of the rest.

A layer of OSB taped at the seams formed the joint at the wall plate where the rafters would sit.

To make a pattern for the lower rafters, the author first made a seat cut based on the roof pitch.

Then he made a plumb cut, again based on the roof pitch.

The rafter was held in place to scribe for the cut where the lower rafter would intersect the main roof.

For a jig, two layers of OSB were cut to fit between the I-joist flanges; then another layer of OSB was screwed on at the correct angle to guide the circular saw.

Where the lower rafter would sit atop the upper rafter at the joint, 1x6 web stiffeners were applied to the I-joists, locateded so they'd line up vertically above the web stiffeners in the lower roof and above the bearing wall.

Join the Discussion

Please read our Content Guidelines before posting

Close X