Figure 4, Cantilevered Outlooker Method Gable End Overhangs: Ladder Outlooker Block Method The uplift at the end of the outlooker imparts an uplift force at the gable truss, which must be resisted by a tension connection such as a hurricane tie, and a downward force at the connection to the full-height truss. At the overhang, wind can cause uplift on both the bottom and top surface. Then the barge or fly rafter is attached to the end of the cantilevered outlooker. Then a 2×4 outlooker is placed over the dropped gable, and butted into the side of the adjacent full-height truss. If a truss roof is used with this method, the gable truss is manufactured 3½” shorter than the others. If you look closely, the end nails from the full-height truss that were in the end of the outlookers can be seen in a couple of places. In the photo above, it appears that the cantilevered outlooker method was used, and that there was a failure of the outlooker connections at the gable end and the first full truss. Figure 2, IRC Gable Overhang Details Figure 3, Gable End Wind Damage Gable End Overhangs: Cantilevered Outlooker Method As far as this author can tell, this area of light construction is not covered in the International Residential Code for wood framing, but it is covered for cold-formed steel framing, where Section R804.3.2.1.2 contains requirements for “Rake overhangs.” The two methods shown are the cantilever outlooker (Option 1) and the ladder outlooker (Option 2). This can be from two causes: inadequate nailing of the sheathing to supporting framing, or inadequate connections of the framing at the rake edge that supports the roof. The other common wind-related failure at gable ends is uplift of the roof decking at the overhang. Figure 1, Gable Wall Bracing Methods Gable End Failure: Uplift of Roof Decking at the Overhang For new construction, Simpson Strong-Tie shows a couple of solutions for bracing top plates of gable ends in our High Wind–Resistant Construction Application Guide on. The support shall be a foundation or floor, ceiling or roof diaphragm or shall be designed in accordance with accepted engineering practice.”įor existing construction, the International Existing Building Code specifies a method for retrofitting gable ends in Appendix C. Since 2009, Section R602.3 has required that “Studs shall be continuous from support at the sole plate to a support at the top plate to resist loads perpendicular to the wall. This is now addressed in the International Residential Code. One is a failure of the hinge at the connection between the top plate of the wall and the gable end framing, if the gable end is not balloon-framed with continuous studs. Gable End Failure: Connection Between Top Plate and Gable End Framing There are two main areas where gable ends can fail. With Hurricane Andrew, the lessons were the importance of protection from windborne debris, and the importance of proper construction of gable end overhangs. It seems that each major hurricane tends to teach those of us in the construction industry some lesson.
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