§ 14-262. Foundations.

(a)

Generally. Foundation walls shall be masonry and shall be continuous under all habitable areas of principal buildings including an attached garage; and shall be designed and constructed to support the loads placed thereon without exceeding the allowable stresses of the materials therein.

Exceptions. Overhanging bays and projecting floors are permitted providing that such cantilevered floors do not exceed four feet. Cantilevered porches and balconies may project six feet providing they do not support a roof. In each case the joists must return twice the distance they project. Clear minimum space of eight inches shall be provided below the bottom of joists to grade.

(b)

Strength. Structural analysis shall be submitted to the building inspector when requested.

(c)

Decay and termite protection. The top of foundation walls under all buildings or structures of wood frame construction shall be at least eight inches above lot grade at all exterior walls, and no exterior wood siding or construction shall be less than six inches above grade.

Exception. Wood pressure treated with a preservative, or of a naturally durable, decay-resistant species and grade of lumber or protected against decay and termites may be used for:

(1)

Sills that rest on concrete or masonry walls and are less than eight inches from exposed earth.

(2)

Ends of wood girders entering masonry or concrete walls and having clearances of less than one-half inch on the top, sides and ends.

(3)

Wood siding less than six inches from the earth.

(4)

Wood embedded in earth.

(5)

All pressure-treated wood shall be identified.

(d)

Foundation wall thickness.

(1)

Concrete foundation walls. Unless designed through structural analysis, the minimum thickness of concrete foundation walls shall be determined from table A; but in no case shall the thickness be less than the thickness of the wall it supports.

(2)

Masonry foundation walls. Unless designed through structural analysis, the masonry foundation walls shall be constructed in accordance with the following requirements:

a.

Unreinforced masonry wall; thickness. The minimum thickness of unreinforced masonry foundation walls shall be determined by table B, but in no case shall the thickness be less than the thickness of the wall it supports.

b.

Reinforced masonry wall; thickness. Reinforced masonry walls shall be reinforced in accordance with the requirements of tables C and D. In partially reinforced masonry walls, vertical reinforcement shall be provided on each side of any opening, at each wall corner, and at intervals indicated in the tables.

(e)

Pilasters. When a girder whose span exceeds 12 feet frames into a masonry wall, pilasters of a minimum size of four inches by 12 inches built integrally with the wall shall be provided.

(f)

Girder bearing. Four inches of end bearing shall be provided for girders framing into foundation wall; and when wood girders are used, an air space shall be provided between the foundation walls and the ends and sides of the girder.

(g)

Dampproofing. Masonry foundation walls of basements and crawl spaces shall be made dampproof by the application to the exterior surfaces thereof of a continuous coat of three-eighths-inch thick waterproof cement mortar or Portland cement mortar plus a coat of bituminous dampproofing material over the parging from top of stone to finish grade. One coat of bituminous dampproofing material shall be applied to concrete foundation wall from top of stone to finish grade. When a minimum of one-eighth-inch thickness of an approved surface bonding cement is applied to an exterior masonry foundation wall, it shall qualify as dampproof.

TABLE A

CONCRETE WALL THICKNESS

Type of Concrete	Nominal Thickness (inches)	Maximum Height of Unbalanced Fill for Material of Wall Being Supported (Wood frame—feet)
3,000 psi	6	6.5
Unreinforced concrete	8 10 12 14	8   9  10  11.5

 

Unbalanced fill is the difference in elevation between the outside grade and the basement floor.

The maximum height of unbalanced fill for a 12-inch thick plain concrete wall may be increased to 12 feet provided the wall is constructed of concrete with a minimum compressive value of 6,000 psi at 28 days.

TABLE B

MAXIMUM DEPTH BELOW GRADE* (HEIGHT OF FILL) AND
THICKNESS FOR VARIOUS CONCRETE MASONRY
FOUNDATION WALLS WITHOUT PILASTERS

	Maximum Depth Below Grade, Feet, When Wall Support
Wall Construction Nominal  Thickness, Inches, and   Type of Unit	Frame Construction (feet)	Masonry, or Masonry Veneer Construction (feet)
Hollow—load bearing
8-inch	5 (6)	6
10-inch	6 (7)	7
12-inch	7	7
Solid load bearing
8-inch	5 (7)	7
10-inch	6 (7)	7
12-inch	7	7

 

* In well-drained sand and gravel soils, the height of the unbalanced fill may be increased to the values in parentheses.

TABLE C

MAXIMUM DEPTH BELOW GRADE (HEIGHT OF FILL) FOR VARIOUS
CONCRETE MASONRY FOUNDATION WALLS WITH PILASTERS

Wall Construction Nominal  Thickness, Inches, and   Type of Unit	Total Height of Wall (feet)	Maximum Pilaster Spacing O.C. (feet)	Pilaster Size (nominal)	Maximum Depth Below Grade (feet)
8-inch hollow load-bearing	7.5	11	16″ × 16″	6.5
8-inch hollow load-bearing with solid pilasters or filled cells of hollow units	7.5	20	16″ × 16″	6.5

 

TABLE D

MAXIMUM DEPTH BELOW GRADE FOR PARTIALLY
REINFORCED MASONRY WALLS

Wall Construction Nominal  Thickness, Inches, and   Type of Unit	Total Height of Wall (feet)	Reinforcement Size and Spacing (feet) Center to Center	Maximum Depth Below Grade (feet)
8-inch hollow load-bearing	7.0 to 8.5	#5 bars @ 8;ft; #6 bars @ 8;ft; #7 bars @ 8;ft;	6.5 7.5 7.5

 

(Code 1983, § 30.19)