Bracing a Steel I-Beam Supporting Wooden Joists


Old 10-20-07, 02:49 PM
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Join Date: Dec 2004
Location: Santa Fe, NM
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Question Bracing a Steel I-Beam Supporting Wooden Joists

In a deck / kitchen remodeling project I have decided to replace an existing 12x4 wooden beam with a sturdier steel I-beam. The existing wood beam spans a distance of around 24', which by my reckoning is just too far for this kind of beam, given the various loads (basically one story with a 5' tributary width). After consulting various tables I've decided that a W10x19 steel I-beam would be perfect.

The existing joists are connected to the side of the wooden beam with joist hangers. I'd like to remove the wooden beam entirely (it makes the deck a few inches too wide), so my plan is to place the new I-beam UNDER the existing joists, near their ends, jack up the I-beam a little, and then put in supporting posts for the I-beam at each end (6x6 P.T. lumber). I will then remove the current wooden beam and replace with a non supporting rim joist.

The one thing I'm not sure about is how best to brace the I-beam horizontally. The load tables I've used mention that the top plate of the I-beam (which is in compression) needs to be braced horizontally every few feet of so. Since the joists will otherwise merely be resting on top of the I-beam, I need a way to connect the I-beam top plate securely to the joists. Are there any standard connectors that are used to connect I-beams to wooden joists resting on top of them? If not, what's the usual way of doing this? We could drill holes in the I-beam top plate underneath the joists and lag bolt into the underside of the joists, but drilling through the I-beam flange at every joist is going to be hard work I suspect. My contractor also suggested simply nailing a 2x2 (or 2x4) strip of wood lengthwise along the beam to the underside of the joists on either side of the I-beam to stop any sideways deflection. Anybody have any comments on this idea?

Any suggestions very welcome!


Old 10-21-07, 04:30 AM
Join Date: Jan 2007
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Bolting a plate on top of the beam would be a great way to go,but try to get some more info from the place you purchased the steel beam on the spacing of the holes to be drilled (you may have to drill less then expected ),(or they may drill them for you)....short of doing that, the only other thing i could recommend would be to take a 2x8 and run it on the diagonal underneath the deck attached to the bottom of every joist.Make sure the 2x8 runs in to the ledger tight , then nail the 2x8 at every joist out to the other corner.

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