Frequently Asked Deck Buildings Questions (continued)

Thanks, I suspected that was the way to go. I would feel better though if 1)the posts were anchored & 2)the posts were raised above the concrete to prevent rot. There are anchors available to do just that. If there is no reason I definitely should not anchor them, I would prefer to do so. That leaves the question of how deep to sink my expansion bolts into the 4 in. thick slab to get maximum hold without causing cracks in the slab.

If you use pressure treated wood, it won't rot. If you intend to sink fasteners in the cement anyway.. I am thinking 3 inches is plenty. My thinking being.. the only thing you need to do is stop lateral movement.. 4 inches is too much since that is the total thickness.

footings for deck

I am building a 17x18 foot deck and the current plans call for footings to be placed along the 14 foot line of the deck. Since the deck is extending out 18 feet from the house, is it safe to have a 4 foot cantilever overhang past the 14 foot line of the deck without using additional footings at the end of the deck? What is the maximum cantilever you would recommend without using additional footings? I will be using pressure treated 2"x8" beams connected to a double 2"x12" crossbeam on top of the footings at the 14 foot line.

Spanning 14 feet, I would use 2x10's not 2x8's. The maximum span for 2x8's is just under 13 feet and you are going over that. A four foot overhang using 2x10's would be fine. As a rule of thumb don't cantilever more than a third of the total length... so 4 feet on an 18 foot span is fine. You can figure the price using two beams one at the 9 foot point and one at the 18 foot point (or just in to give you an overhang). Spanning 9 feet you can use 2x6 joists. The savings might outweigh the cost of the additional beam and posts. One other thing.. on your design... I figure the posts should be every four feet (no more!) on your 2x12 beam if you are only using one beam. Using two beams with 9 ft spans on the joists, you can use posts ever 6 ft.