![]() Hips: Often Function Much Like a Non-Structural Ridge Board As such, we have separated the discussion of each into two separate sections. However, based on our review of the member loadings, there are fundamental differences between hips and valleys that should be considered and that dictate different design and construction practices. Where the roof pitch is less than THREE UNITS IN 12 units horizontal (25-percent slope), structural members that support rafters and ceilings joists, such as ridge beams, HIPS AND VALLEYS, shall be designed as BEAMS.”Īs can be seen, the IRC requirements for hips and valleys are lumped together and generally follow much of the same requirements of ridge boards and ridge beams. Hip and valley rafters shall be supported at the ridge by a BRACE to a bearing partition or be designed to carry and distribute the specific load at that point. “At valleys and hips there shall be a valley or hip rafter not less than 2-inch (51 mm) nominal THICKNESS and not less in DEPTH than the cut end of the rafter. The IRC requirements for hip and valley beams are relatively brief and listed as follows in Section R802.3: Now that we have established the definition and basic function of hips and valley beams, let’s move on to the specific requirements of the building code regarding hip and valley beams along with illustrative examples on why those requirements exist. ![]() “ JACK RAFTER – A rafter that spans from a hip or valley beam to a wall plate or ridge, respectively.” ![]() These rafters are referred to as jack rafters and are defined as follows: In order to form a convex hip or concave valley, the rafters framing into the hip or valley beams on both sides need to be cut to varying lengths to accommodate the diagonal slope of the hip or valley beams. A common valley configuration is shown in Figure 2 (adopted from the 2018 WFCM to illustrate the various components). ![]() In the situation of a valley, all the jack rafters are inherently oriented downward toward the valley, creating loading behavior like a center floor girder that takes loading from joists. “VALLEY BEAM – A beam spanning from the ridge to an INSIDE ROOF CORNER, that supports the jack rafters, forming a CONCAVE roof line.” A valley beam or valley rafter provides the main structural support for the valley shape and is defined by the WFCM as follows: To form an opposite, concave (inward) shape in the roof system, a “valley” can be used and is often located at the intersection of different roof sections, e.g., when two gable roof sections intersect or in an “L”-shaped building configuration. A common hip roof configuration is shown in Figure 1 below (adopted from the 2018 WFCM to illustrate the various components). It primarily functions as a nailing board between opposing jack rafters. The hip beam can be thought of as a secondary ridge that spans from the outside corner to the main peak of the roof. “ HIP BEAM – A beam spanning from the ridge to the OUTSIDE ROOF CORNER that supports the jack rafters, forming a CONVEX roof line.” A hip beam or hip rafter provides the main structural support for a hip shape and is defined by the Wood Frame Construction Manual (“WFCM”) produced by the American Wood Council (“AWC”) as follows: Instead of a uniform triangular shape across the entire length of the roof, the corners of a conventional system can be framed into a convex (outward) shape at the corners to form a “hip.” The ridge can even be eliminated all together with the corners coming together to form a single peak in the case of a pyramid hip roof. In the previous posts, we introduced the most common “conventional system” of roof framing wherein the roof is constructed with rafters along each slope with ceiling joists along the bottom enclosing an attic space and resembling a triangular shape when viewed from the side. Hips And Valleys: Function, Configuration and Code Requirements Similar requirements and principles exist across other IRC editions and industry standards as well. Unfortunately, along with the appealing aesthetics comes increased complexity of rooflines and increased potential for construction and design defects.Ĭode references throughout our discussion come from the 2015 edition of the International Residential Code (“IRC”), the most common edition currently adopted across the United States. Using hips and valleys to create multi-faceted roofs is extremely common in residential construction as it makes for more dynamic and interesting rooflines. Collar Ties now in our third post, we discuss the function and proper construction of hips and valleys. We’ve discussed Ridge Boards vs Ridge Beams and Rafter Ties vs. In our three-part series on residential roof framing basics, we’re examining critical components of residential roofs and the common misunderstandings related to these components, which often result in costly property damage, liability claims, and litigation.
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