b'YOUR TOOLKIT FOR BUILDING EXCELLENCEincreased wind uplift zones.3.Slender BuildingsBuildings that are long and narrow (Figure 5) present a specific load path issue. Roofing and siding material often provide lateral strength and stiffness to resist lateral loads in Post-Frame buildings from wind and seismic sources. Gable walls (shear walls) and the roof (diaphragm) must be designed to provide this resistance, referred to as diaphragm action; however, diaphragm action can run into limitations in buildings with high length to width Figure 3 Plan View of a Partially Enclosed Buildingratios (typically greater than 2.5). When diaphragm showing internal pressurization35 action is inadequate, additional shear walls, interior 2.Increased Wind Pressure at Roof Edges and CornersRoof edges and corners must be designed for increased wind uplift load based on the physics of wind flowing over the edges and surfaces of a building (Figure 4). One method to address this wind uplift is to add additional screws to fasten the purlin to the truss top chord, perhaps one screw in each of the first three purlins at the eave and the upper three purlins at the ridge.Additional fasteners may also be needed between purlins and trusses at the gable and/or near the eave. An alternative detail to adding screws is to add an uplift strap or Figure 5 Long buildings relative to span create challengestwist clip to each purlin in regions in or near thebracing or exterior buttresses may be required to fortify such buildings.4. Roof Truss to Column ConnectionLike roof edge uplift, trusses or rafters must be tied to the header or post with enough strength to resist the uplift load path from the roof system (Figure 6). This connection may involve the truss to post, truss to header, or header to post. Uplift forces in this connection will be larger if the building is partially enclosed.5. Snow Drifts and Sliding SnowLoadpathforsnowloadsmust consider areas of increased load dueFigure 4 Plan View of Gable Roof Zones with example uplift pressures. continued on page: 16 FRAME BUILDER - NOV2022 / 15'