The L&I website is pretty easy, and even has sample plans to follow during the app. process. Respectfully, if the process isn't understood its because a qualified builder should handle most of this process.
http://www.phila.gov/li/faq/permits/deckinfo/index.html
The City of Philadelphia requires all individuals to obtain permits prior to constructing a wood deck for a single family dwelling that is 12 -inches or more above the ground. The cost is $52.00 to cover the $25.00 Zoning permit, $25.00 Building permit and the $2.00 State fee. If construction is started without a permit and a violation is issued, an additional special inspection fee will be imposed equal to the Building and Zoning permit fees.
REQUIREMENTS
General Construction
All lumber must be pressure treated or naturally durable, such as redwood or cedar
All hardware must be non-corrosive
The foundation must be a minimum of 2'6" below ground
The guardrail vertical balusters may have a maximum opening of 4"
Complex decks and/or deck exceeding 400 sq. ft in area are required to be certified by an registered architect or engineer
Zoning Requirements
Complete a Zoning Permit Application
Provide six (6) copies of a Plot Plan.
Definition
Example
The plot plan will be reviewed for compliance with following Zoning requirements
The deck can not be located in the front or side yard.
The guard rail height may be a minimum of 36-inches and a maximum of 42-inches.
The deck can not have a roof, walls, stairs, or an enclosure beneath the deck.
Deck supports must not prevent vehicle access to the garage or parking space, regardless of its use.
A minimum distance of 3-feet must be maintained from the deck to the rear property line or common driveway.
All support columns must have a 1-foot,
6-inch clearance from the side lot lines if they are within 4-feet, 6-inches of the common driveway.
For decks above driveways, the clearance between the lowest horizontal support beam and the driveway must be at least 6 feet.
A deck attached to buildings located on the corner must not extend beyond the building line.
Building Requirements
Complete the Building Permit Application
Provide three (3) copies of a sketch of the deck, including:
Size and spacing of joists
Size and spacing of posts
Size of beam
Siz and method to attachment of ledger
Height of deck above grade
Sample Plan View
Sample Cross Section Sketch