Expert: Dan Griffin - 10/20/2011

Question
I recently purchased a wood framed ranch with a full below grade basement in the Syracuse, New York area.  I want to finish a portion of the basement to use as a recreation area.  The section I want to finish is approximately 27' X 29-1/2' with floor joists running the the 27' length.  Running the 29-1/2' length is a steel I-beam specified as W8X15 with two steel support posts spaced approximately equal distance from either wall.  As I mentioned, the house is a single level ranch and above the basement area that I am finishing, there is standard residential items (furniture) with no load bearing walls.  The house also uses a truss roof system.  In the rec room, I plan on putting a billiard table in and, ideally, I would like to remove one the support posts requiring the I-beam to span approximately 19-1/2' (eliminating any obstructions for playing pool).  Will this beam support the load?  If not, what would be the maximum span for this beam under these conditions or what size beam would be required (preferably a W8X??)?  Is there any way the existing beam can be modified or added to to extend the span (such as welding additional steel plates, square tubing or I beams)?

Answer
Ed, I'm sorry I am not a structural engineer.  I am fairly sure that welding a side plate on each side of the existing beam will solve your problem.  It would also be possible to go to a heavier 8" beam.  You really need to have a structural engineer design the remedy.