Track and stud Flat Truss design
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Light-gauge steel Floor Truss assembly guide

Light-gauge steel Floor Truss also known as parallel cord trusses or flat trusses are useful for spanning floors. With a large demand and supply chain issues with open-web trusses and bar joists, light-gauge steel is a stable alternative for building your own floor or ceiling trusses. In this article I’ll show you to build floor trusses up to 20′ long.

Components & member sizing

Light-gauge steel Floor Truss assembly guide

To build a Light-gauge steel truss you will need a top and a top and a bottom cord known as track and smaller studs which will be known as “webs.” For 12′-22′ floor trusses we recommend using 16 ga (54 mil) 3 5/8″ track and stud(362S162-54). For less than 12′ the 18 ga equivalent stud and track is fine(362S162-43). We build all our floor trusses 16″ as this a a height were you can maximize spans.

Stud to track Connection type

We used hex head self tapping screws. We recommend two in each connection as shown to the right for longer trusses and one for shorter trusses. Hex heads are the easiest to work with. Other recommend tools are steel vice grips, and wide wood clamps(for clamping the width to make sure the height stays at 16″)

Light-gauge steel Floor Truss assembly guide

10′ Floor truss cut lengths

To build a 10′ floor truss you should use 18 gauge tracks and studs. You will need 8 web stud pieces each 19.45″ and two end studs at 15.65″. Two 10 ft tracks. Use this respective pattern for the 10′ floor truss.

Light-gauge steel Floor Truss assembly guide
10′ spacing pattern

15′ Floor truss cut lengths

To build a 15′ floor truss you should use 16 gauge tracks and studs. You will need 12 web stud pieces each 19.546″ and two end studs at 15.65″. Two 15 ft tracks. Use this respective pattern for the 15′ floor truss.

Light-gauge steel Floor Truss assembly guide
15′ Spacing pattern

20′ Floor truss cut lengths

To build a 20′ floor truss you should use 16 gauge tracks and studs. You will need 16 web stud pieces each 19.6″ and two end studs at 15.65″. Two 20 ft tracks. Use this respective pattern for the 20′ floor truss.

Light-gauge steel Floor Truss assembly guide

Assembly process

If you’re building multiple trusses of the same size the best bet is to build a fitting square. Then simply place your studs in there and trill from the top. Mark the approximate location of where to place the webs, doesn’t have to be perfect of make sure you get the height right. If you want pre-cut studs you can always order them from us at USFrameFactory.

Wall connection

In this particular installation the client used Simpson Strong-Tie S/LBV Hanger. As you can see you attach them to the steel beam using self tapping steel screws and simply slide the joist in. Alternatively you can drill the end peace directly the wall or supporting post.

Other Recourses

Click here to learn about building light gauge steel headers.
Click here to regular joists spans.

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