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Re: Sizing Steel I Beam for Basement Clear Span

From: fclaridge@yahoo.com
Category: Structural
Remote Name: 64.122.124.242
Date: 13 Feb 2006
Time: 11:52 PM

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Question: I need to replace the beams that are sagging in my basement supporting the main floor. There are (2) 6x6 beams that meet together at the center and sit atop a 6x6 wood post. The beams bear on the concrete foundation walls at either end. I would like to make the span of 20 feet using a steel I beam and eliminate the post, thus opening up the space below. What size I beam would be needed to accomplish this? Thanks.

Builders Websource® Answer: Unfortunately, you have not provided enough information to make an accurate computation. However, you note that the existing wood beams are sagging, which indicates they were probably undersized at the outset. Specifically, one would need to have a loading diagram that shows all the loads imparted on the beam from above, including tributary loads and any point loads from load-bearing walls, such as might be supporting a second floor or roof load. Furthermore, analysis would be required to ensure that there is sufficient strength and reinforcement of the foundation footing and walls to support the extra load on each end of the steel I beam, including fastening details. We urge you to consult with a licensed structural engineer who can do a proper load analysis, factoring in all other loads such as wind, seismic, and snow loads that may be present in your area.

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