Expert: Bruce E. Johnson - 2/25/2010

Question
My nephew just purchased a home in Philly.  There was lots of remodeling done. One of the items was replacement of the main support beam for the house.  They sistered (nailed) 3 2x10's together but the boards don't run the full span and they spliced pieces in.  My concern is the splicing in of short pieces. Is this acceptable? Is nailing the proper method of securing the sistered boards?

Answer
Hi Sam, there are some instances, if properly designed, a spliced beam as you mention is acceptable.  Generally a span can be divided into thirds and then the thirds spliced with equal lengths  so that each layer has a splice point at a different location. This will result in smaller pieces of 1/6th lengths at opposite ends of the beam. The method of attachment can be nails in a staggered pattern and preferably with a good construction adhesive between layers.  As to what the nail spacing requirements are depends largely on the span but 4-6" is pretty common with no nails closer than 2" to the edge.  The shear value of the nails should outperform the stress values of the wood.  Unless there is a lot of movement in the beam under normal "live load" conditions or prominent sagging under "dead load" conditions then your beam has been sized and built properly.  You didn't say who designed the beam so I have to assume that a structural engineer did especially if this was a substantial properly "permitted" remodel project. I hope this information helps, please feel free to write agin regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com