I have 4 8 inch concrete piers spaced @ 6' 7 inches apart and would like to construct a double 2x10 beam 24' long
That would give me 2 foot overhang on each end
I have 14' 2 x 10
Where and how would I join them?
Typically beam splices are required to be aligned over a post, see Figure 3 of the International Residential Code for deck design, 2006 edition. If you are not building to this code, your requirements may be different. Beams composed of multiple lumber members are assembled in accordance with Figure 4 of IRC 2006, which shows the required nailing pattern and nail size. Maximum beam cantilever is in accordance with figure 3, which allows Lb/4 maximum, where Lb is the c-c distance between posts. In your case, you state the posts are 6'7" (79 inches) c-c, so maximum overhang is 19-3/4 inches according to IRC code, so your proposed 2 foot overhang would not be acceptable.
Again, if you are working to a different code, this may not apply. If you hire an engineer to design the deck and stamp the plans, you are typically allowed to deviate from code. Your local building inspector is generally permitted to allow you to deviate from code, so you may wish to consult with them in advance if you cannot live with code requirements.
The Following User Says Thank You to Daniel Holzman For This Useful Post: