Expert: Dan Griffin - 7/24/2011

Question
All wood, 24' wide x 30' long x 10' high garage in Arvada Colorado. Built garage in August of 2010, all work has been inspected and passed our local code requirements. I wold like to now add a steel beam that would span across the 24' wide part, and could handle a maximum of 4,000 lbs. of lift out in the center of the floor. I cannot find any type of load chart to calculate the size of a steel beam needed or if the span can be made with out any center support. I will support each side with the correct size of steel uprights and plates, if a measurement can be found. I will then take this information and drawings to our local code office for the approval. Any information would be appreciated, thank you.

Answer
Kevid, I'm sorry but I don't have the credentials or expertise to size such a beam.  a 4000# point load on a 24' beam will be substantial.

Here is one source that I do have:
http://www.cousesteel.com/AndysPlace/SteelChart.html

the way I read it:

25' span (similar to yours) capable of 2 ton (your 4000#) would need a 12" I beam.

The difficulty comes from how steel is sold.  There is no official beam named an I beam.  There are H, W, and M beams of many different weights per lineal foot.  A typical beam would be labeled something like a W12 x 40 where the 12 indicates the beam being 12" from top flange to bottom flange and weighing 40lbs. per lineal foot.

A call to your local steel supplier with this much information will probably get you what you need.