Floor Truss Bridging

Bottom of the floor joists instead of or in addition to being installed on top.

Floor truss bridging.

The 2x6 serves the same purpose as bridging in a standard floor distributing concentrated loads over a wider area. Bridging allows each joist to share weight with its neighbors and can cut deflection how much the joists flex by half. Lay the new sheets perpendicular to the floor joists and orient panel ends over joists. However some people add additional bridging to try and stiffen the floor and provide additional load sharing or to brace the joists per nds 4 4 1.

Tension bridging works only in tension so must be used in cross pairs. The catch of course is that the bouncy floor joists must be accessible from below. Intervals one run for a 20 ft. Support floor joists with a depth to thickness ratio of six or more with bridging at intervals not exceeding 8.

Underneath 2x6 strongbacks laid on edge should run continuously through the webs of all the trusses at 10 ft. Even if your floor already has a row of bridging running down the center you can stiffen it substantially by adding two more rows. All open joist truss layout plans include strongback bridging specification and location. Pony or pratt truss bridges are half through truss bridges no overhead members box or full through truss overhead members two types of pony truss configurations.

U section bridge under hung floor beam generally for shorter spans. Ansi tpi 1 2002 includes information in the commentary to section 7 5 2 4 regarding the use of strongback bridging to reduce the effects of differential deflection in floor trusses. The load sharing element is typically considered to be the floor diaphragm. Truss two runs for longer trusses.

If span is greater than 16 use more than one pair. I ve always used a lift for upper floors though. The code does recognize load sharing through the value of cr. Floor truss open concept allow the installation of strongback bridging which actively contribute to reduce floor vibration.

If span is greater than 8 install on 2x8 or larger joists. Floor truss is designed and produced to your specific needs and delivers reliable performance. Floor joist bridging is critical to the structural strength of a floor as shown in figure 1. Proper bridging distributes the load on the floor to other joists and over time prevents floors from sagging and squeaking do to floor joists twisting and warping.

Details to minimize the chance of future squeaks and to help secure the new floor sheath ing start by spreading a generous amount of construction adhesive over the old planks.