[Amended by Ord. No. 76-21]
A. Support. The foundation of every permanent structure shall be supported
by satisfactory bearing materials such as natural deposits of rock,
gravel, sand, inorganic salt, clay or any combination thereof which
does not contain an appreciable amount of organic matter.
B. Freezing. No footing or foundation shall be placed on frozen soil.
Footings or poured foundations shall not be laid in freezing weather
unless adequately protected.
C. Materials. Footings shall be poured concrete designed to sustain 2,000 pounds per square inch or better, except for wood foundations (see Subsection
L).
[Amended by Ord. No. 79-19]
D. Dimensions.
(1) Concrete footings for load-bearing walls shall be of adequate dimensions to distribute the load to the supporting soil. Minimum thickness shall be eight inches. Footing width shall extend six inches on each side of the wall above. Footings for any building or structure shall be constructed of concrete or reinforced concrete or wood (see Subsection
L) and shall extend below the adjoining grade a minimum of three feet six inches. Masonry units used in foundation walls, appendages and stoops shall be laid in portland cement mortar, plumb and in alignment.
[Amended by Ord. No. 76-22; Ord. No. 79-20]
(2) Concrete footings for piers and columns shall be a minimum of two
feet square and a minimum thickness of 10 inches and shall be designed
to carry the superimposed load. Columns shall be centered on column
footings.
(3) The following tables provide for the minimum wall thickness requirements:
|
|
Thickness of Foundation Walls
(inches)
|
---|
|
Number of Stories
|
Concrete
|
Unit Masonry
|
---|
|
Table I: Masonry and Masonry Veneer Buildings
|
|
1
|
10
|
12
|
|
2
|
12
|
12
|
|
3
|
12
|
12
|
|
Table II: Light Incombustible and Wood Frame Buildings
|
|
1
|
8
|
10
|
|
2
|
8
|
12
|
|
3
|
12
|
12
|
E. Chimney footings. Chimney footing shall be six inches wider all around
than chimney size and 12 inches thick. Chimney footings shall start
at the level of lowest adjacent foundation wall footings.
F. Fireplace footings. Fireplace footings shall be 12 inches wider all
around than fireplace, with reinforcing rods eight inches apart across
at right angles and not less than 12 inches deep.
G. Height above ground. Foundation walls supporting wood members shall
extend at least six inches above the finished grade and shall conform
with the grade of existing homes within the block, and in no case
shall construction begin without first having obtained approval of
grades from the Public Works Director/City Engineer.
[Amended 7-5-2022 by Ord. No. 22-63]
H. Foundation ventilation. The space between the bottom of floor joists
and the ground of a dwelling (except space as is occupied by a basement
or cellar) shall be provided with ventilating openings through foundation
walls or exterior walls. There shall be not less than two ventilating
openings, the minimum total area of which shall be proportioned on
the basis of 1/2 square foot for each 25 linear feet or major fraction
thereof of exterior wall. Minimum clearance between bottom of floor
joists and the ground beneath shall be 18 inches.
I. Concrete slabs on ground. Earth under slab bed shall be leveled and
tamped. Wire mesh reinforcing, when required, shall have a minimum
weight of 20 pounds per 100 square feet.
J. Foundation walls. Walls of hollow masonry units shall be capped with
minimum of four inches of solid masonry or poured concrete. If concrete
is used, reinforce with wire mesh. Hollow masonry unit foundation
walls supporting girder shall be capped under the girder with solid
masonry or poured concrete a minimum of six inches in height.
K. Pilasters.
(1) Concrete walls. Pilasters shall be provided where girders frame into
six-inch poured concrete walls; minimum size of pilasters: two inches
by 12 inches poured integrally with wall.
(2) Masonry walls. Pilasters shall be provided where girders whose clear
span exceeds 12 feet frame into eight-inch masonry walls; minimum
size: four inches by 12 inches built integrally with wall. Also, one
pilaster eight inches by 16 inches shall be required for every 20
feet of wall.
(3) Girder pockets. Provide four-inch end bearing for girder. Provide
one-half-inch air space between pocket and sides and end of wood girder.
L. Wood foundation system. Wood foundations shall be designed and constructed
in accordance with the following adopted standard of the National
Forest Products Association and listed exceptions: The All-Weather
Wood Foundation System, Basic Requirements, Technical Report No. 7.
(1) Exceptions:
(a)
Fasteners. Fasteners for use in preservative-treated wood shall
meet the requirements of this section. Fasteners of silicon bronze
or copper or stainless steel Type 304 or 316, as defined by the American
Iron and Steel Institute classification, shall be permitted in preservative-treated
wood above or below grade. Fasteners or fastener materials not otherwise
permitted under this section shall be permitted if adequate comparative
tests for durability, including the effects associated with wood-treating
chemicals, demonstrate performance equal to or greater than the specified
fasteners or fastener materials.
(b)
Plastic film. Six-mil-thick polyethylene sheeting shall be supplied
over the below-grade portion of exterior basement walls prior to backfilling.
Joints in the polyethylene sheeting shall be lapped at least six inches
and bonded. The top edge of the polyethylene sheeting shall be bonded
to the plywood sheathing. A treated lumber or plywood strip shall
be attached to the wall to cover the top edge to the polyethylene
sheeting. The wood strip shall extend several inches above and below
finish grade level to protect the polyethylene from exposure to light
and from mechanical damage at or near grade. The joint between the
strip and the wall shall be caulked full length prior to fastening
the strip to the wall. Alternatively, asbestos-cement board, brick
stucco or other covering may be used in place of the wood strip. The
polyethylene sheeting shall extend down to the bottom of the wood
footing plate but shall not overlap or extend into the gravel footing.
(c)
The thickness of the wood foundation wall shall be no less than
two by six, 16 inches on center.
(2) Materials. All lumber and plywood shall be treated in accordance
with the following adopted standard and shall be identified as to
conformance with such standard by an approved inspection agency: Quality
Control Program for Soft-Wood Lumber, Timber and Plywood Pressure
Treated with Water-Borne Preservatives for Ground Contact Use in Residential
and Light Commercial Foundations.
(a)
Height of foundation wall above grade. All foundation walls
shall be designed and constructed to provide at least eight inches
of clearance between grade and untreated wood. Note: This section
is not intended to apply to untreated wood applied on the interior
side of foundation walls.
(b)
Where lumber is cut after treatment, the cut surface shall be
brush-coated with not less than a three-percent solution of the same
preservative in the original treatment.
[Added by Ord. No. 79-18]
M. Foot drain tile.
(1) Bleeder tile. Nonperforated, perforated tile, or equivalent, of a
minimum of three inches in diameter, shall be embedded in concrete
footings of all new buildings where any basement or usable crawl space
three feet and greater is proposed (and be spaced in said footing
not to exceed eight feet, more or less apart). This tile, hereafter
called "bleeder tile," shall be placed in the footings between the
main building and an attached section like a garage with the floor
at grade, and around footings of existing building additions where
a full depth basement is proposed. Bleeder tile openings, both inside
and outside of footings, shall be free of any debris and shall be
covered with crushed stone or equivalent acceptable material to permit
water to course freely to and through the bleeder tile.
(2) Exterior drain tile. Perforated tile shall be installed around the
outside perimeter of any basement wall, be placed on the footing and
covered with a minimum of one foot of crushed stone or similar acceptable
material. In the event the tile cannot be placed on footings, it shall
then be placed alongside the footing on not less than two inches of
stone or similar acceptable material and covered with not less than
one foot of like material.
(3) Interior drain tile. Perforated tile shall be placed alongside of
the footing and upon not less than one inch of crushed stone or similar
acceptable material and covered with not less than one inch of like
material to allow the unobstructed flow of water into the tile. All
tiles shall terminate in a clear water sump crock located a minimum
of one inch above the basement floor or to an approved gravity drainage
system.
(4) Sheathing. Where clear sand is encountered or any type of soil that
could cause an obstruction of the tile, the tile shall be wrapped
with a porous nylon sheathing or similar acceptable material to preclude
the entrance of granules into the drain tile.
(5) Exceptions. Drain tile requirements shall not apply in the following
situations:
[Amended by Ord. No. 89-102]
(a)
Buildings constructed with an all-weather wood foundation system
as per Technical Report No. 7, Basic Requirements, National Forest
Products Association, Washington, D.C.
(b)
Additions to existing buildings where crawl space only is proposed.
The erection of a prefabricated building or use of prefabricated assembly, the integral parts of which have been built up or assembled prior to incorporation in the building, shall be permitted, subject to all other provisions of this chapter and according to Chapter
550, Zoning.