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Re: Steel Beam Size

From: info@builderswebsource.com
Category: Structural
Remote Name: 63.198.181.43
Date: 26 Jan 2002
Time: 06:31 PM

Comments

Assuming no roof load is transferred to interior floor joists or beams, then we would recommend something along the following lines. Please note that you should always consult a licensed structural engineer in your state who can run calcuations for you based on your actual conditions.

Given your overall layout and the fact that there is no conveninet place to put a post, we would recommend that you span the 40' direction with either a steel I beam, or a glulam. The I beam will be shallower, so if beam depth is an issue, you should consider this route.

The steel I beam or glulam should be centered along the short wall (at approximately 14' from either end).

Then, we recommend 2x12 floor joists running perpendicular from the I beam (using joist hangers) out to the long walls. Since the floor joists will only span 14' now, you can use a 16" o.c. spacing and have a very stiff floor.

The size of the I beam or glulam depends on how stiff you want to specify the floor. So, there are MANY possible solutions. Here are just a couple that give you a "ballpark" estimate. Again, this must be cross-checked with an engineer. In both cases, we minimize deflection by specifying a minimum of SPAN/480 for the live load. Generally, the following recommendations are even more conservative.

You could use a Glulam in the range of 10-3/4"x28-1/2" GLB 24F-V4 DF/DF with approximately a 0.5" camber. The camber helps to offset the deflection due to dead load.

Or your could use a steel I beam, such as a W16x 100 (measuring 10-3/8" x 17") with about a 0.5" camber also.

Either path will yield a large beam, requiring a small crane or hydraulic jack to put into place. The mounting techniques require further structural design, as well as possible reinforcement to the foundation where the loads will be transferred on either end.

Also, you may need LVLs or GLULAMS or steel I beams as your garage headers to take the loads from the floor, the 2nd story walls, and any loads transferred from the roof.

Since there are several beams that will need to be sized, a structural engineer is essential. Safety is #1. But also be sure the specifies a stiff enough beam to prevent bounce. This can be very noticeable on long spans such as this. Spend the money and do it right. The structural integrity of your project is the most important thing!

Another alternative to using a large beam is to take a look at the new structural engineered wood products, including wood "I beams" such as those from GP and others. In looking at the span charts, it is possible to span the entire 28' width of your garage by using a 16" depth with 12" o.c. spacing. Other options are available as well.

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