Expert: Dan Griffin - 4/30/2008

Question
Dan,
I am remodeling a home built in the late 1940's.   The home is constructed out of long leaf pine.  Our game room 2x10 joists stand 11' 5" above our garage.  The joists span a distance of 19 ft.  The joists are on 16" centers and cross braced with 1x4's every 8'.  Teh exterior and interior walls are built with 2x6's and all interior and exterior wall are sheathed with 3/4" lap board from 8" up to 16" in width.  The decking on the floor is tounge and groove that runs @ 45% with a redwood floor nailed to it.

My plan is to put a pool table in the game room (24x20).  The pool table is an 8ft table and it weighs approx 780lbs.

Will the current span hold the load of the pool table and the friends who come over?  

Will I need to build a strong back in the center of the floor joists and obtain one or two adjustable steel columns to support the strong back from the garage floor?


Answer
4 big fellas @ 200# - 800.  Pool table @ 800 - total load about 1600 at mid span.  Pool table about 4x8 plus player's space - about 8x12=96 SF.  That ends up around 17 lbs/SF.

Here is an excellent joist calculator that I have entered your data to:
http://www.awc.org/calculators/span/reversecalc/reversecalc.asp?feet=19&inches=0...

The indication suggests you are over span right now and increasing the concentrated load would require some additional support.  The floor will not fail suddenly.  You could carefully measure the garage ceiling height at mid span before loading.  The L/360 deflection for 19' is .6333 (about 5/8").  The span table says you already have about .95 (almost an 1" with a 30# live load/10# dead load.  Measure the deflection caused by the pool table.

It sounds as if you would just be better off to reinforce.