Issue link: http://alpine.uberflip.com/i/405142
Floor Systems Floor Systems 33 Another popular application for truss systems is in floor systems. Floor systems can be trussed, conventionally framed, or built with engineered wood products such as I-Joists. Both trusses and engineered wood products are engineered, and have wider nailing surfaces for the floor decking. Trusses are built with open chases for ductwork and have natural open spaces for plumbing and electrical wiring. Some engineered wood products have specified or marked notches that can be removed to allow for the same. Floor truss systems are sometimes called System 42's, because to build them manufacturers turn the 2x4's on their side. This allows for shallow depths as well as a 3 1 / 2 " nailing surface. Some floors are built from 3x2's, others from 2x4's. Floor trusses can be manufactured with many different possible end conditions to accommodate different installation needs; around raised walls, pocketed beams, headers around stairways, etc. In addition, some manufacturers are taking advantage of adding an I-Joist to the end of a truss to make it a trim-able end. Then the truss can be manufactured just a bit long, and easily trimmed back as needed in the field. Two of the most common web patterns for floor trusses appear below: Is it OK to move a floor truss? Typical floor trusses are engineered to be spaced evenly, and the truss design drawing will tell you how far apart the trusses are designed to be. Occasionally the need will arise to shift one of the floor trusses from where it was designed to be. When this happens, please contact the truss manufacturer to be sure it works. Sliding a floor truss even a few inches puts more load on the truss you're moving it away from, as shown in the drawing below. Fan configuration web style Warren configuration web style I I F F YOU YOU SHIFT SHIFT IT IT : : T T HEN HEN THE THE OVERSTRESSED OVERSTRESSED TRUSS TRUSS CARRIES CARRIES : : B B 24" 3" 6.2% more load than it was designed for 27" on center 6" 12.5% " 30" trusses 9" 18.7% " 33" 16" 3" 9.3% more load than it was designed for 19" on center 6" 18.7% " 22" trusses 9" 28.1% " 25" Check with Check with the tr the tr uss uss manufactur manufactur er er befor befor e e shifting a tr shifting a tr uss ! uss !