I'm designing a new free-standing 14 ft deep x 18 ft wide deck to replace my old poorly constructed deck from the previous house owner. This new deck will have pressure treated yellow pine 2 x 8 joists and 2 x 10 beams on 6 x 6 posts resting on 12 inch dia footings (36 inches deep by code in my area 40 miles west of Philadelphia). There are 6 footings. The beam span is 7 ft 1 inch and the joist span is 9 ft 5 inches. The joist spacing is 16 inches on center and I will be using Western red cedar for the decking and railings.
This deck is not high, it's top is only 25 inches from grade at the patio door and then the grade slopes away from the house until the top of the deck is about 37 inches above grade. The decking is parallel to the 18 ft width so my joists are running perpendicular to the house. I will be placing one of those grates I saw in FHB mag in place of one of the deck boards before the door to help with reducing tracking mud in to the house.
My question is, since I can't get 18 ft long beams, how do I splice the beams at that middle post? Is a butt joint there OK or is a half-lap type joint better. SEE THE ATTACHED DRAWING. I show the half lap in the isometric view in the upper right of the drawing.
Also, my local Home Depot, supplies their pressure treated lumber in the yellow pine variety. Is Yellow Pine the same as Southern Pine? I ask this because the span tables show that southern pine is stronger in bending than the Doug fir-Larch-Hem Fir group.
SEE MY ATTACHED DRAWING (pdf or jpg)
Thanks to all in advance.