A.
General. Footings shall be of adequate bearing area to safely distribute
all live and dead loads to the supporting soil without exceeding the
bearing capacity of the soil. Footings placed in unstable soils shall
be formed.
B.
Type and size. Concrete footings, unless designed by structural analysis,
shall comply with the following requirements:
(1)
Continuous footings. The minimum width on each side of the foundation
wall shall measure at least four inches wider than the wall and the
minimum depth shall be eight inches.
(2)
Pier and column footings. The minimum horizontal dimensions of column
or pier footings shall be two feet by two feet and shall be at least
12 inches in depth.
(3)
Stepped footings.
(a)
Where variations in the elevations of the bottom wall footings
are necessary, it shall be spanned with an approved lintel.
(b)
Exception. A vertical connection between the footings at the
step may be constructed of concrete, eight inches thick and of the
same width as the footings, if there is less than two feet difference
in elevation.
(4)
Chimney and fireplace footings. Footings for chimneys or fireplaces
shall be at least four inches wider than the outside dimension of
the chimney or fireplace foundation and at least 12 inches thick.
(5)
Trench footings. Footings poured integrally with the wall, at least
eight inches wide, may be used for a one-story structure when soil
conditions assure that trench walls will not collapse.
C.
Frost protection. The bottom of all footings shall be a minimum of
four feet below grade. Footings shall not be placed upon frozen material.
D.
Curing. Concrete footings shall cure at least 24 hours before foundation
wall or wall forms are begun to be constructed.
E.
Drain tiles. All foundation walls of basements, cellars or other occupied spaces shall have drain tiles on each side of such walls. [See § 756-21B(3) for basementless spaces.] Bleeder tiles shall be placed in the foundation footing at not more than eight-foot centers. Drain tiles shall be connected to a sump pit, provided with a pump to discharge the water at grade or shall be connected to the storm sewer house drain. Drain tiles shall be covered with 12 inches of No. 2 washed stone or other approved porous material. Drain tile and stone shall be placed prior to starting the fourth foundation block course.
A.
General.
(1)
Foundation walls shall be of masonry and shall be continuous under
all areas of the principal building including attached garage and
shall be designed and constructed to support the loads placed thereon
without exceeding the allowable stresses of the materials therein.
(2)
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.
(1)
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.
(2)
Exception.
(a)
Wood pressure treated with a preservative, or naturally durable
decay-resistant species and grade of lumber or protected against decay
and termites, may be used for:
[1]
Sills which 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 1/2 inch on top, sides and ends.
[3]
Wood siding less than six inches from the earth.
[4]
Wood embedded in earth.
(b)
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 756-19A, 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 walls; thickness. The minimum thickness
of unreinforced masonry foundation walls shall be determined by Table
756-19B, but in no case shall the thickness be less than the thickness
of the wall it supports.
(b)
Reinforced masonry walls; thickness. Reinforced masonry walls
shall be reinforced in accordance with the requirements of Tables
756-19C and 756-19D. 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.
Damp-proofing. Masonry foundation walls of basements and crawl spaces
shall be made damp-proof 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
damp-proofing material over the parging from top of stone to finish
grade. One coat of bituminous damp-proofing material shall be applied
to concrete foundation wall from the top of the stone to finish grade.
When a minimum of one-eighth-inch thickness of an approved surface
bonding cement is applied to exterior masonry foundation wall, it
shall qualify as damp-proof.
|
Table 756-19A
Concrete Wall Thickness
| |||
|---|---|---|---|
|
Type of Concrete
|
Nominal Thickness
(inches)
|
Maximum Height of Unbalanced Fill1 for Wood Frame Wall Being Supported
(feet)
| |
|
3,000 psi
|
6
|
6.5
| |
|
Unreinforced concrete
|
8
|
8
| |
|
10
|
9
| ||
|
122
|
10
| ||
|
14
|
11.5
| ||
|
NOTES:
| ||
|---|---|---|
|
1
|
Unbalanced fill is the difference in elevation between the outside
grade and the basement floor.
| |
|
2
|
The maximum height of unbalanced fill for a twelve-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 756-19B
Maximum Depth Below Grade* (Height of Fill) and
Thickness for Various Concrete Masonry Foundation
Walls Without Pilasters
| ||||
|---|---|---|---|---|
|
Maximum Depth Below Grade (feet) When Wall Supports
| ||||
|
Type of Unit
Wall Construction Nominal Thickness (inches)
|
Frame Construction
|
Masonry or Masonry Veneer Construction
| ||
|
Hollow — load bearing
| ||||
|
8
|
5 (6)
|
6
| ||
|
10
|
6 (7)
|
7
| ||
|
12
|
7
|
7
| ||
|
Solid — load bearing
| ||||
|
8
|
5 (7)
|
7
| ||
|
10
|
6 (7)
|
7
| ||
|
12
|
7
|
7
| ||
|
NOTES:
| ||
|---|---|---|
|
*
|
In well-drained sand and gravel soils, the height of the unbalanced
fill may be increased to the values in parentheses.
| |
|
Table 756-19C
Maximum Depth Below Grade (Height of Fill)
for Various Concrete Masonry Foundation Walls With Pilasters
| |||||
|---|---|---|---|---|---|
|
Type of Unit
Wall Construction Nominal Thickness (inches)
|
Total Height of Wall
(feet)
|
Maximum Pilaster Spacing O.C.
(feet)
|
Pilaster Size (Nominal)
(inches)
|
Maximum Depth Below Grade
(feet)
| |
|
8 hollow load-bearing
|
7.5
|
11
|
16 x 16
|
6.5
| |
|
8 hollow load-bearing with solid pilasters or filled cells of
hollow units
|
7.5
|
20
|
16 x 16
|
6.5
| |
|
Table 756-19D
Maximum Depth Below Grade for Partially Reinforced Masonry
Walls
| ||||
|---|---|---|---|---|
|
Type of Unit
Wall Construction Nominal Thickness (inches)
|
Total Height of Wall
(feet)
|
Reinforcement Size and Spacing (feet) Center to Center
|
Maximum Depth Below Grade
(feet)
| |
|
8 hollow load-bearing
|
7.0 to 8.5
|
No. 5 Bars at 8
|
6.5
| |
|
No. 6 Bars at 8
|
7.5
| |||
|
No. 7 Bars at 8
|
7.5
| |||
