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Re: Wood beam spanning 30' over garage?

From: info@builderswebsource.com
Category: Structural
Remote Name: 172.183.246.167
Date: 28 Dec 2001
Time: 10:04 AM

Comments

A 30-foot beam supporting a second story without a center support is a substantial beam. You will most likely need either a beefy glulam, LVL or steel I-Beam. Anything less will probably fail to meet acceptable deflection criteria. When making any structural decision between two or three alternatives, occupant safety always comes first over cost. While it's prudent to be cost conscious, we would recommend an "engeered" wood or steel solution that has readily quantifiable strength characteristics. Built-up beams made from 2x and plywood are very difficult to specify because there are too many variables, such as the type of wood, the number and thickness of plies, the glue used, the number and spacing of bolts, the wood moisture content, etc.

With a few more questions, we can estimate the size of beam you'll need to give you a ball park. We need to know whether the beam is in the center of the 30'x30' span (that is, 15' of load on each side of the beam). Also, are there any additional loads transferred to the beam, such as roof loads, attics, etc. If you are using trusses, most of the loads will be transferred to the outside walls. If you're using traditional stick framing, part of the roof load will be transfered to an internal load-bearing wall, which in turn will be transferred to the beam. We would need to know any point or distrubuted loads and their amounts.

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