After setting the girder truss a specified distance from the corner, hip jack trusses and end jack trusses are attached to the girder truss with metal hangers. Girder trusses are also used for hip roof packages. Then, when the trusses from the main rectangle of the house are set, the ends adjacent to the wing are supported by metal hangers affixed to the girder truss.Īfter the common trusses are set, valley trusses are installed on top of them to form the valleys. On these houses, the girder trusses are set first, extending across the opening to the intersecting wing. The trusses and the mechanical fasteners used to tie them together must be specified by the truss fabricator. Because these multi-ply trusses support a huge amount of weight, they should never be designed on site. Girder trusses are typically made from several trusses that are fastened together on site.

On some houses, valley trusses are used in conjunction with girder trusses to create a wide opening between the main house and the intersection wing. After sheathing the main house, use step-down valley trusses to build the intersection are on top of the roof deck. To build these valleys with trusses, you run the first roof frame straight through the main section of the house. When a house has one section running perpendicular to another, the intersecting roofs form valleys. To support the roof over a porch without using posts, designers sometimes specify cantilever trusses. Because these trusses exert no thrusting force on the walls, horizontal restraints, such as exposed beams or cables, are not necessary.Īttic trusses are designed with open spaces above the bottom chord that can be used for storage or for living space. Scissor trusses are used to construct cathedral ceilings in rooms with wide spans between bearing walls. After you set all the trusses, you can install a rake that passes over the drop-top truss and ties into the first truss inside the wall. These are dropped the width of the top chord (usually 31⁄2 in.) from the common trusses in the package. Where rake overhangs are planned, truss suppliers can fabricate drop-top gable-end trusses.

Using gable-end trusses saves time by eliminating the need to frame a gable-end wall. However, this configuration gives the gable frame little tensile strength and it must rest on the end wall of the house. Instead of a series of interlocking triangles, they have vertical pieces set at intervals of 16 in. They are frames built in the shape of the other trusses in a package. Strictly speaking, gable-end “trusses” are not trusses. and, thanks to computers, packages for all common roof shapes can be designed and built quickly and precisely. Trusses can be made for spans in excess of 50 ft.

Trussed roof