How do i plan footings for a deck?

Question

Ive built many a deck for the company i work with, but my boss always lays the footings and i work from there, ive learned everything i need to know to build a deck with any kind of material, except how to plan out footings, can somebody explain to me how i figure out how many footing i need and the maximum space between them, when i may need to have two rows to support a secont girter under the joists etc.

Answer 1

Try this site

http://www.lowes.com/lowes/lkn?action=ho...

Answer 2

i do not know the answer sorry

Answer 3

While the individual codes in your area may differ, generally the posts are set no more than 8 ft. apart and the end ones are no more than 2 ft. from the edge of the deck.  They all must be within 2 ft. of the outer edge of the deck, as well.  The posts are set in the ground below the frost depth, 24" in my area and must set on undisturbed soil.  Many houses are built with backfill against the foundation.  I've seen posts that needed to be set 6 ft. into the ground to set on undisturbed soil.  The inspector will have a rod he pokes the ground with to tell if the footings will be solid.  There are different ways and amounts of concrete to pour depending on the way the post is being attached to the concrete.  You should just need one row of posts, as long as the deck is attached to the house band board with a ledger board.  If there is some reason it is a free-standing deck (cannot be attached to house for support), then there needs to be a row of posts within 2 feet of the house and possibly diagonal supports installed.

A simple way to design a deck is to use the Trex deck designer on their website.  It even gives you a 3D picture and materials list for the design.  

http://www.trex.com/deckdesigner/default...

Answer 4

With all due respect, the "planning" might differ for each individual deck. In your doing the finish work, don't you get a sense of how your boss works, at least?

   I've built many a deck too, and never found the same conditions twice. I've poured footers and installed 4 x 4's at

8 ft/ 4 ft centers, often. I've doubled often.  As I said, so much of it depends on size of the finished product, the design, then it's potential or very real load bearing issues, soil conditions, grades, etc.

  In some sense the number of footers depends on the overall size of the deck, and any multiple levels to it.

  The smallest deck I built was for a house I used to own. The deck is 12 x 18. I used 4 corners of course, poured to allow 8 ft. beams centered on 24 inches inside the exterior framing, supported at the perimeter and center. That equated to 6 footers and posts, with decking, fractionally overhanging after. That deck supports 4 x 4's which support a roof, so I poured 36 inch footers.

   I build decks, much as I would frame a house, no longer pour and bury supports, choosing to use pier block instead. I've also poured using Sauna tubes for graded areas. I also no longer use anything but 2 x stock for the deck surface, unless it's a composite.

  I truly mean no offense, but it's a Deck. While I realize this is Sunday, and YOU may not have worked, perhaps your boss didn't either, have you ever questioned him?

Steven Wolf

AKA: The Deck Doc

Just my two "sense"