This detail outlines the attachment of roof purlins and eave struts at a rigid frame end-wall when a rake/purlin extension (Overhangs) is a building feature. The upper diagram/animation shows the purlin attachment and the lower diagram shows the eave-strut. Also shown in this detail is the installation of the rake angle at both the purlin and eave-strut and a flange brace at the purlin.

Unless called out differently in the building construction drawings, the end of the purlin only requires (2) 1/2” A307 bolts and nuts; however, (4) bolts can be installed if desired. These should be installed diagonally, and a 1/2” washer needs to be installed on the purlin side at the slotted hole.

The Eave-strut and Purlin will both extend past the building’s steel line. The Eave-Strut uses (4) 1/2“ A307 bolts with washers. This connection is through the bottom flange of the eave-strut rather than through the web. On low-slope buildings, it is possible to rest the eave strut on top of the rafter while placing bolts. However, a strap or rope should be used to prevent the eave-strut from sliding off of the rafter until it is secured with bolts and nuts.

Purlin Extensions are measured from the building steel line (where the wall panels attach to the building’s framing), but measurements shown in this detail are measured from the center of the purlin clip pre-welded on the rafter’s top flange.

Please see detail SD1 for a description and animation of the installation of the rake angle.

Click here to view a PDF drawing of SD10