Originally Posted by boman47k
Since this is a freestanding deck, I will use doubled 2x8's all around, I guess.
I must say that decks should never be built by 'guessing'.
Decks should always be built by calculations.
Your preliminary design will dictate your calculations. Your calculations will give you your dimensions for your beam, footings, joists and other key structural information.
These all contribute to the overall structural stability that equal, your safety and the safety of all those that you care about.
There are mathmatical/engineering reasons for specific lumber dimensions, footing sizes/depths, post-placement distances, beam depth and width, why certain
joists are doubled, why a beam is tripled, and so forth. Code requirements for connection points and what fasteners to use.
Example of other factors - Do you know what a ''crown'' is on a stuctural piece of lumber that will be used for a joist? Do you know where that crown should face? This is very important.
Check with your local area to see what requirements or guidelines your building dept. has for constructing a deck.
Please do alot of research
concerning general deck structural design and weight load calculations. Once you do that, do your design on paper before you attempt anything. Have someone with experience look it over and critic it.... Please ?
Review joist span information and structural requirements. In most US jurisdictions, a building permit is in fact, required to build a deck.
For starters, Use 2x10's (not 2x8's for that span).....
Here's some examples of Town/City requirements for decks (please check YOUR local requirements):