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Re: Selecting a Beam to Support Room Above Garage

From: williamejacobs@yahoo.com
Category: Structural
Remote Name: 134.134.136.1
Date: 04 Nov 2005
Time: 06:57 PM

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Question: I am designing a room above a garage. This room will house a pool table and serve as a family room. My plan is to use attic trusses. The span is 28 feet. Assuming that I will need a beam under the trusses in order to have a stable floor under a substantial load presented by the pool table and the live load of several people, and assuming that I can place a beam along the centerline of the trusses, what are my options for beam material? Should I consider steel? What are the cost implications of steel v wood lam?

Builders Websource® Answer: The choice of steel vs. wood beam depends on several factors such as:

• Method of attachment to the end columns
• Beam span
• Desired floor stiffness based on all live and dead loads
• Acceptable depth of beam into the room below (garage in your case)
• Materials and installation cost
• General familiarity with construction methods (mixing wood with steel construction tends to be more expensive)
• Local availability of materials

The longer the clear span, the more steel starts to make sense due to its excellent stiffness per unit length for a given depth. Always consult a licensed structural engineer who can supply not only the proper beam size (and material), but can specify the camber, the mechanical connections, the columns, and the foundation load analysis and recommendations.

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