Foundations Minimum Requirements

Unfinished Basement Without Concrete Floor Slab

Perimeter foundation permits can be issued "over the counter" if the proposed building is not going to be raised and there are no exterior alterations proposed to the building.

• The following plans are required:
  • Plot plan
  • Foundation Plan showing location of proposed work and indicating the number of stories of the structure
  • Foundation construction detail. (See attached standard details.)

Finished Basement With Concrete Floor Slab

Perimeter foundation permits may be approved "over the counter" for projects where new concrete floor slabs are installed but where the building is not raised and there are no exterior alterations proposed.

• The following plans are required:
  • Plot plan
  • Foundation Plan showing location of proposed work and indicating the number of stories of the structure
  • Cross section of the building showing existing and proposed ground to wood clearance, basement headroom and number of stories in the building
  • Basement floor plans showing existing and proposed use of every space including any area that is not intended as living space (laundry, workshop, storage). Any area not intended as living space must be designated as "non-habitable space" on the plans.
  • No heating or air conditioning can be permitted in any "non-habitable space."
  • Details of all proposed wall and ceiling finishes as well as any proposed electrical plumbing or mechanical fixtures.

Note: Private garages must be separated from the dwelling unit and its attic area by means of a minimum 1/2" gypsum board applied to the garage side. Garages beneath habitable rooms must be separated from rooms above by not less than 5/8" Type 'X' gypsum board. Doors openings between a private garage and the dwelling unit are required equipped with a self-closing, self-latching door that is either a solid wood or solid core or honeycomb core steel door not less than 1-3/8" thick, or a 20-minute rated door.

Retaining Wall Standard

General Assumptions

• F’c = 2,500 PSI MIN
• Fy = 40,000 PSI MIN
• Allowable soil bearing capacity = 1,500 PSF
• Equivalent fluid pressure on the wall is limited to 30 PCF
• Wall supports maximum of two (2) floors and a roof with a max tributary width of 10’-0” for a max vertical load limited of 1,000 PLF
• Owner must provide dampproofing per CBC Section 1807.2
• Owner must take measures to reduce hydrostatic pressure build up per CBC Section 1807.4
• Owner must check the adequacy of this minimum standard for each specific project

Wall Component Specifications

• Stud Wall
• Pressure treated sill plate with 5/8” diameter galvanized anchor bolt with 7” embed and 3”x3”x0.229” plate washer @ 6’-0” max
• Vertical #4 Rebar: Steel reinforcement bars placed at 18” O.C. (on center) typically throughout the vertical stem wall to provide structural strength
• Horizontal #4 Rebar: A minimum of (2) horizontal steel reinforcement bars placed at 18” O.C. within the wall for lateral stability
• 4” MIN Slab on Grade: A concrete interior floor with a minimum thickness of 4 inches, installed where the interior floor meets the retaining wall
• Footing Reinforcement (#4 Rebar): Additional steel reinforcement placed at 18” O.C. each way (longitudinal and transverse) when the footing depth (S) is greater than 0 inches
• Exterior sheathing
• Edge nailing
• Finished grade

Retaining Wall Data Tables

H: Total wall height from the top of the footing to the top of the stem wall.
W: Total width of the concrete footing.
A: The distance from the exterior face of the stem wall to the edge of the footing.
S: The depth of the footing extension below the base.

With Slab on Grade

Without Slab on Grade

Minimum Foundations for Non-Engineered Construction

Note: Concrete mix shall be 2,500 PSI @ 28 days.

One (1) Story Foundation Requirements

• 2x4 MIN pressure treated sill plate with 5/8” diameter galvanized anchor bolt with 7” embed and 3”x3”x0.229” plate washer @ 6’-0” MAX
• Finish grade
• #4 rebar continuous top and bottom

Two (2) Story Foundation Requirements

• 2x6 MIN pressure treated sill plate with 5/8” diameter galvanized anchor bolt with 7” embed and 3”x3”x0.229” plate washer @ 4’-0” MAX
• #4 rebar continuous top and bottom

Three (3) Story Foundation Requirements

• 2x6 MIN pressure treated sill plate with 5/8” diameter galvanized anchor bolt with 7” embed and 3”x3”x0.229” plate washer @ 4’-0” MAX
• (1) #4 rebar continuous at top; (2) #4 rebar continuous at bottom

Revised August 27, 2014