Can a 8 1/2" x 13 1/2" beam safely span 24 feet?
Mike
Off hand, I can’t say.
What was the loading?..How long has it been there?..Was there any deflection?
Also, what material or species is the beam made from? How is it loaded?
We need to know what the composite of the beam consists of, and the size and loading above. Ex. farm house, dwelling, carport floor, etc.
Marcel 
Michael, you don’t have to do calculations or look up Tables of Allowable Spans or determine beam material to follow the Standards of Practice, just call out problems. As Larry asked, was there deflection? -Kent
3 year old 2 story Lindal style home in the flood plane. No deflection noted , gluelam. I have no problem with the install, i was just curious.
Mike
A ROT for timber, double the depth, subtract 2, this is the span in feet (13.5x2=27-2=25’. This is assuming a rafter condition i.e. uniform loading, fixed connections. Be careful with this ROT because loading points and connections are huge factors in the overall performance of the beam.
Thats a loaded question … particularly for a Glulam or LVL beam. I agree it’s best to just look for visible signs of defects, and then call it a day … 