Wood Truss Details3.3

Terminal Hip Framing-The hip jacks extenddirectly to the peak. The distance from the end wallto the face of the girder is equal to one half the span,provided the slopes are equal. The last standardtruss is designed as a girder to carry the loads

Step Down Hip Framing-The Step Down hip is themost versatile of all hip types. Each of the stepdown trusses is the same span and has the sameoverhang as the adjacent standard trusses, butdecrease in height to form the end slope. The girderlocation is generally from 8 to 12 feet from the endwall and is determined by the span to depth ratio.The corner and end jacks are normally pre-built.

Midwest Hip Framing-Developed to create amore uniform configuration of each of thetrusses in the hip. This hip type also providesfor a more uniform structure for attaching thedecking.

California Hip Framing-Although not usedextensively this is another alternative to the stepdown hip. The base portion of each truss inside thegirder is the same, except that the sloping top chordof each successive truss is extended upward greateramount to form the slope intersection. Corner andend jacks are used to form the area outside thegirder.

Hip FramingTrussed hip framing offers the advantage of clear span, an eave or facia line at the same elevation around the building, andthe speed of pre-built components. The end slope may be equal to or different from the side slope. The ceiling line may beflat or sloped. Sloped ceilings have limitations; therefore, consult with your truss designer.

Wood Truss Details3.3

Girder TrussesGirder trusses have two main purposes. The first(Girder Truss A) exists in L, T, H, and U shapedbuildings to eliminate the need for an interior load-bearing wall. The girder is used to support one end ofthe intersecting trusses. The trusses are carried on thebottom chord of the girder by hangers.The second use of a girder truss (Girder B) is to supportperpendicular framing in hip roofs. In some plans girdertruss A and B may be on in the same. The hip framing iscarried on both the top and bottom chords of the girdertruss by nailing or by hangers.Girder trusses, because of the heavy loads they support,are generally multiple units with larger chord membersthan the adjacent trusses. Generally, because of theconstruction of girders, overhangs are not used.The girder truss may also be designed for drag strutloads which are calculated and specified by the buildingdesigner.

Valley Framing SetsValley framing sets are primarily used to form a ridgeline by framing over the main roof whereperpendicular building sections intersect.Valley trusses are set directly on the main trusses.Sheathing is required on the top chords under valleyframes to continue the lateral bracing of the maintrusses. The bottom chords of the valley trusses canbe bevelled to match the slope of the roof below.

Wood Truss Details3.3

Gable FramingGable ends when not configured in triangles as a truss are more related to stud walls. However, they are structuralelements and are analyzed to resist wind and seismic loads as noted on the truss design. The web design may bedetermined by the type of siding or the need for a louver in the end of the building. The type of gable required iscontrolled by the end overhang and the need to match a soffit line.

Transition GableA transition gable is required when a run of smaller spantrusses leads up to parallel longer span trusses. It will facelateral wind loads in the area where it is not shielded by thesmaller span trusses and have to carry the roof load where itdoes not have continuous support

Clear Span GableA clear span gable must span from one wall to another. Ithas to have diagonal webs to help distribute the load out tothe walls, but it also needs to have vertical gable studs tohelp the gable sheathing resist lateral wind forces.

Wood Truss Details3.3

Cantilevers and OverhangsCantilever conditions are common intruss designs. A cantilever exists whenthe bearing wall occurs inside of thetruss overall length, excludingoverhangs.When the bearing is located under thescarf line of the truss, no heel jointmodification is needed. Wedge blocksor sliders are used to stiffen the heelpanel when the bearing is moved insidethe scarf line. Wedge blocks act tostiffen the heel joint and are connected tothe top and bottom chord with connectorplates located over or just inside thebearing. Sliders allow longer cantileversby stiffening the top and bottom chordsin the heel panel.

OverhangOverhang

Overhang Overhang

Overhang Overhang

The additional web is addedwhen the cantilever distance istoo long for use with the wedgeblock or reinforcing member.

THIS MEMBER OFTENREQUIRES CONTINUOUSLATERAL BRACING

VariesUsually12

Wood Truss Details3.3Typical Flat Truss End Details

Mansard FramesMansard details are normally built onto the truss. However, there are design situations where it is more appropriate tohave the mansard frame installed independent of the roof framing. Those occasions might be when the use of the buildingdictates a construction type requiring masonry exterior walls and a non-combustible roof.

Wood Truss Details3.3

Typical Roof Truss Bearing Conditions

Typical Bottom Chord endcondition

Typical Bottom Chord endcondition without overhang

Raised Heel with or without asloped ceiling

Bottom Chord bearing in ahanger

Tail Bearing TrayIf the room calls for a tray ofcoffered ceiling very close to thebearing the truss can look like this.It may require a scab to be attached.Consult with your truss designer

Wood Truss Details3.3

Typical Roof Truss Bearing Conditions

Top Chord Bearing Mid-Height Bearing

Leg-Thru Bearing Flat Roof Parapet

Wood Truss Details3.3

Piggyback TrussesWhen roof trusses are too tall to bemanufactured and/or delivered, trussmanufactures will supply piggybacktrusses. The piggybacks below areshown above the roof so that thepurlin and bracing system can beseen. Special diagonal bracing onthe underside of the top chords helpsbrace the purlins themselves, andkeeps them from shifting out ofplane. The preferred method is tosheath the top chords of the bottomtrusses. The piggyback trusses canbe designed using either verticalstuds or diagonal webs.

Detail of the bracing system,with purlins and diagonal braces

Wood Truss Details3.3Wood Truss Floor Systems

Floor systems can betrussed, conventionallyframed, or built withengineered wood products.Both trusses andengineered wood productsare engineered and havewider nailing surfaces forthe floor decking. Trussescan be built with openchases for ductwork andhave natural open spacesfor plumbing and electricalwiring.Floor trusses can bemanufactured with manydifferent possible endconditions to accommodatedifferent installation needs;around raised walls,pocketed beams, headersaround stairways, etc.

Wood Truss Details3.3Wood Truss Floor Systems

Parallel stairwell openings do not present aproblem. Multiple ply floor trusses mayrequire special connection details between theplys. Special connections will be specified onthe design.

Perpendicular stairwell openings mayrequire addition posts or bearing walls. Allloads from stairs and surrounding wallsmust be considered for correct floor trussdesign. Trusses may be supported as topchord bearing or by hangers. Headers maybe supported by approved hangers

Typical DuctOpening Sizes for4x2 Floor Trusses.

Openings and weblocations may varydepending on loads.

If a certain opening isrequired specify it onthe drawing.