[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.
Masonry chimneys. Masonry chimneys shall be constructed gastight
and shall bear on masonry or concrete foundations.
B.
Effective flue area for fireplace. Effective flue area for a fireplace:
not less than 1/10 of fireplace opening. Separate flues required for
each fireplace.
C.
Flue linings. Fire clay flue lining supported on masonry or concrete
shall be installed in all chimneys from a point below the breaching
to the top of chimney. Two flues may be grouped without wythes, provided
joints of linings are staggered. The flue linings of fireplaces and
chimneys shall be backed up with at least four inches of masonry of
the proper fire-resistant material to adequately support and protect
the flue linings. All chimney and fireplaces must have flue linings
not less than eight inches except where gas is used, then four inches
or six inches can be used.
D.
Chimney cap. Chimney cap shall be provided to form wash from flue
to outside edge of chimney; minimum thickness at outside edge: two
inches.
E.
Thimbles. Thimbles and cleanout doors shall be built in at the time
chimney is constructed.
F.
Cleanout doors. Every chimney shall be provided with a cleanout opening
equipped with a metal cleanout door and frame.
G.
Framing around chimney. Wood lath, furring or framing shall be placed
not less than two inches from any chimney.
H.
Chimney height. All chimneys shall extend at least six inches above
the ridge of the roof that the chimney penetrates and not less than
six inches above the highest ridge within 10 feet of the chimney.
A.
Definition. In conventional frame wall construction, all structural
parts are of wood or are dependent upon a wood frame for support.
This includes walls with facing or wood frame for support and walls
with facing or veneer other than wood, such as brick, tile, stone
and stucco.
B.
Studding. Wall studding of frame building shall not be less than
two inches by four inches, 16 inches center to center. One-story detached
garages and other accessory buildings may have studding spaced 24
inches center to center.
C.
Base plates. For garages and porches, stud walls resting on masonry
shall have base plates bolted to the masonry at corners and between
corners, with bolts not less than 1/2 inch in diameter embedded not
less than seven inches into the masonry and spaced not more than eight
feet apart, center to center. These sills shall be not less than the
width of the studs nor less than two inches thick.
D.
Plates. In bearing partitions, the top plate shall be doubled and
lapped at each intersection with walls or partitions. Joints in the
upper and lower members of the top plate shall be staggered not less
than four feet.
E.
Bridging. All stud partitions or walls over 10 feet in height shall
have herringbone bridging, not less than two inches in thickness and
of the same width as the studs, fitted snugly and spiked into the
stud at mid-height of the stud, or other means for giving equal lateral
support to the studs.
F.
Corners and bracing. Angles at corners where stud walls or partitions
meet shall be framed solid so that no lath can extend from one room
to another. All exterior and main cross-stud partitions shall be effectively
and thoroughly braced.
G.
Window and door opening. All windows and door openings on bearing
walls and partitions must have double headers. All bearing openings
between and including three feet to five feet must be headed with
two pieces of two inches by six inches set on edge. All bearing openings
over five feet and not over eight feet wide must be headed by two
pieces of two inches by eight inches set on edge. All bearing openings
over eight feet and not over 10 feet must be headed by two pieces
of two inches by 10 inches set on edge. All bearing openings over
10 feet and not over 12 feet must be headed by two pieces of two inches
by 12 inches set on edge. All headers must have shoulder studs. Front
entrance door shall be not less than three feet wide, and side or
back entrance door shall be not less than two feet eight inches.
H.
Firestopping. Firestopping shall be installed at every floor level
to cut off all concealed draft openings and form an effectual horizontal
fire barrier between stories and roof spaces.
I.
Sheathing. Sheathing shall be required over studs, except in one-story
detached garages and other accessory buildings. Wood boards, when
applied diagonally, shall extend at 45° in opposite directions
from each corner. Sheathing shall be applied solidly over the wall
surface and properly nailed to each stud with not less than two eight-penny
nails for boards four inches to eight inches in width, and three nails
for 10 inches to 12 inches in width. Sheathing shall be of one or
more of the following materials:
J.
Paper or felt. All wood sheathing shall be covered with water-resistant
building paper or saturated asphalt felt. Each lap shall be not less
than four inches, with at least a four-inch lay around opening, with
at least 15 lb. felt or equivalent.
K.
Plywood. Where plywood is used for covering the exterior of outside
sheathing walls, it shall be of the exterior type not less than 3/8
inch thick. Joints shall be backed solid with nailing pieces not less
than two inches wide.
L.
Ledger boards. Ledger or ribbon boards used to support joists shall
be not less than one inch by four inches, shall be cut into the studs
and securely nailed to each stud. Where ledger boards are used, the
outside walls shall be completely firestopped with not less than two-inch
material.
A.
Thickness.
(1)
Masonry veneer applied to the walls of frame structures shall rest
directly upon the masonry foundation of the structure and shall be
not less than 3 3/4 inches in thickness. Such veneer shall be
backed up with waterproof building paper or saturated felt, which
shall extend down below the joist and, where insulated sheathing is
used, the joists are also covered.
(2)
Minimum thickness, brick: 3 3/4 inches. Ashlar stone masonry
dwellings less than two stories high: three inches; two-story dwellings:
four inches. Rubble stone masonry, uncoursed (field stone): 12 inches;
mosaic or random: 12 inches; coursed dwellings less than two stories
high: eight inches; two-story dwellings: 12 inches.
B.
Flashing. Flashing shall be installed where necessary to prevent
moisture from penetrating behind the wall.
C.
Anchorage. The masonry veneer shall be securely attached to the frame
structure at intervals of not more than 16 inches horizontally and
24 inches vertically.
D.
Sheathing. Sheathing shall be securely attached to the framework of the structure back of the masonry veneer by properly nailing to each stud as specified in § 253-30I, and in all cases, before applying masonry veneer, a substantial waterproof paper of asphalt-saturated felt shall be applied as required in § 253-30J.
A.
Flashing. Flashing or other measures adequate to prevent penetration
of moisture behind the stucco surface shall be used where necessary.
B.
Back plastering. Back plastering shall be required where sheathing
or its equivalent is omitted.
C.
Sheathing. Sheathing shall be securely attached to the framework of the structure back of the masonry veneer by properly nailing to each stud as specified in § 253-30I, and in all cases, before applying masonry veneer, a substantial waterproof paper of asphalt-saturated felt shall be applied as required in § 253-30J.
D.
Metal lath. Where metal lath is used for the stucco base, it shall
be expanded galvanized metal lath weighing not less than 3.4 pounds
per square yard, or wire fabric not lighter than No. 19 gauge.
A.
Strength and soundness. All members shall be so framed, anchored,
tied and braced together as to develop the maximum strength and rigidity
necessary for the purpose for which they are used. No member shall
be stressed in excess of the strength of its details and connections.
B.
Size of members. All wooden members shall be of sufficient size and
strength to carry the load safely without exceeding the allowable
working stresses of the material.
C.
Beams. Every beam, girder and joist shall have end bearing in accordance
with compression perpendicular to grain, values, but the length of
end bearing shall never be less than four inches on masonry or concrete
or 1 1/2 inches on metal, except that joists when nailed to the
adjacent studs shall be supported on a one-inch let-in ribbon. Wood
members bearing on or in contact with masonry or concrete at or below
adjacent ground level shall be treated with an approved preservative
or provided with a moisture-resistant separation over bearing or contact.
D.
Spaced columns. The following table gives maximum spans for wood
floor beams for various joist sizes. If steel beams are used, columns
shall be spaced according to manufacturer's specifications.[1]
[1]
Editor's Note: The Table of Maximum Spans for Wood Floor Beams is included as an attachment to this chapter.
E.
Double joists. Joists under bearing partitions shall be doubled unless
supported by a partition underneath. Joists under and parallel to
bearing partitions shall be doubled and well spiked or may be separated
by solid bridging spaced at not more than four-foot intervals.
F.
Floor joist support. Floor joists shall be supported by girders which
bear on exterior walls or partitions, except floor joists heading
into stairwells or similar headers.
G.
Floor joist bridging.
(1)
Solid wood blocking of two-inch nominal thickness, wood cross bridging
of not less than one inch by four inches or metal cross bridging of
equal strength shall be placed between joists where the joist span
exceeds eight feet. Solid blocking shall be placed between joists
at all points of support and at all points where flooring is not continuous,
except that bridging at bearing may be omitted when the joists are
nailed to studs. The lower ends of the cross bridging shall be driven
up and nailed after the floor or subflooring has been nailed.
(2)
Solid blocking not less than two inches nominal thickness and full
depth of the joists shall be provided in the following places: over
all bearing walls, bearing partitions and around all stairways or
other vertical openings; and over all girders, except when joists
are not sealed on the underside thereof. Such solid blocking shall
serve as firestopping and as the required bridging.
H.
Allowable spans. The maximum spans for wood floor joists shall be
as listed in the following table. The table is based on allowable
live load of 40 pounds per square foot on floor joists supporting
a plastered ceiling below.[2]
[2]
Editor's Note: The Table of Maximum Span of Wood Floor Joist for Use in Dwellings is included as an attachment to this chapter.
I.
Plywood flooring. When plywood is used as finished flooring, it shall
be laid over a subflooring and the plywood shall be 5/16 inch thick
for a twelve-inch span, 3/8 inch thick for a sixteen-inch span, and
5/8 inch thick for a twenty-four-inch span.
A.
Cement floors. Minimum thickness: four inches. When concrete slab
on ground is used as finish floor or the base for other finish flooring
in habitable rooms, the construction of the floor and base shall be
such that water or dampness will not penetrate the slab. Normal construction
precautions against water or dampness will require one or a combination
of the following under all conditions:
(1)
Four-inch-thick bed of clean gravel or crushed stone of uniform size,
drained if below grade. Provision must be made to prevent cement paste
or fines of concrete from filling the voids of the bed.
(2)
Two-ply membrane waterproofing, mopped between layers with hot tar
or hot asphalt, turned up to top of slab at edges and, when below
grade, extended up enclosing walls to six inches above grade or equivalent.
B.
Basement floor slabs. Minimum thickness: three inches. Bottom of
slab shall be not lower than top of footing. Slab shall continue over
footing projection to foundation wall.
C.
Garage floor slabs. Minimum thickness: four inches. Provide slab
at least two feet in front of garage for opening to form an apron;
slope to driveway.
D.
Terrace and porch floor slabs. Minimum thickness: four inches, and
reinforced with wire mesh or rods. Metal flashing or two 15 lb. felts
shall be installed between slabs and all wood construction.
E.
Driveways and walks. Minimum slab thickness: four inches. Expansion
joints shall be provided at garage apron and at thirty-foot intervals.
A trowel-cut approximately halfway through the slab of walks shall
be made at approximately four-foot intervals.
A.
Roof framing. Roofs shall be so framed and tied into framework and
supporting walls as to form an integral part of the whole building.
B.
Spans for roof rafters. The maximum spans for rafters shall be as
listed in the following table, based on a live load of 30 pounds per
square foot plus a dead load of five pounds per square foot.[1]
(1)
The allowable span of roof rafters shall be measured from plate to
ridge, except that where rafters are braced to ceiling joists and
a complete truss is formed, the span shall be considered as the distance
between intersecting points of trussing.
(2)
The table below is for rafters with slopes of less than four in 12.
For slopes of four in 12 to 12 in 12, increase below lengths by one
foot six inches; for slopes of 12 in 12 and greater, increase below
lengths by two feet six inches.
(3)
For spacing for woods different from the tables below, joist and
rafters shall be determined on a basis equal to the following tables.[2]
[2]
Editor's Note: The Table of Spacing of Roof Rafters and the Table of Maximum Spans for Ceiling Joists are included as attachments to this chapter.
(4)
Stress values for individual species of lumber shall be determined
from the latest edition of National Design Specifications for Stress
Grade Lumber and Its Fastenings.
[1]
Editor's Note: The Table of Spacing of Roof Rafters is included as an attachment to this chapter.
C.
Collar beams. Collar beams on every other rafter shall be required
when the roof pitch is six inches and under, and collar beams shall
be of one-inch by six-inch lumber.
D.
Trussing. Trussing shall be required on rafters 15 feet and over,
measuring from stud to ridge board. Spacing shall not be more than
four feet apart, and one-inch by six-inch rough lumber or larger shall
be used.
E.
Roof trusses. If built-up roof trusses are used, they shall be of
the size and space according to the manufacturer's specifications.
F.
Plywood roofs. If plywood is used on roofs, the minimum thickness
shall be 3/8 inch spacing, and 1/2 inch thick for twenty-four-inch
spacing. Nailing shall be not less than six-inch spacing.
G.
Spans for ceiling joist.
(1)
The maximum spans for ceiling joists shall be as listed in the following
table.[3]
[3]
Editor's Note: The Table of Maximum Spans for Ceiling Joists is included as an attachment to this chapter.
(2)
Stress values and modulus of elasticity for individual species of
lumber shall be determined from the latest edition of National Design
Specifications for Stress Grade Lumber and Its Fastenings.
H.
Attics. All residences shall have access provided to the attic space
by means of a stairway or permanent ladder or a scuttle not less than
22 inches square. Adequate ventilation shall be provided in all spaces
between the roof and top floor ceiling by means of louvers or other
approval vents. The net area of each ventilation opening shall be
not less than 144 square inches, and such openings shall be so located
as to provide effective cross ventilation.
A.
Window areas. The window or skylight area for each livable room must
be at least 1/8 of actual floor area, excluding bathroom, where a
ventilating fan must be provided if there is no window.
B.
Ventilation. Where more than 1/2 of the required windows in a room
are fixed, ventilation shall be provided by louvers or other approved
devices.
A.
Width. Stairs shall be not less than 36 inches in width in the rough.
B.
Rise and tread. All stairways shall have a uniform rise of not more
than eight inches and a uniform tread of not less than nine inches
measuring from tread to tread and from riser to riser.
C.
Handrails. All stairways and steps of more than four risers shall
have at least one handrail mounted on the open side, if any. Stairs
five feet or more in width, or open on both sides, shall have a handrail
on each side.
D.
Headroom. Every interior stairway shall have a headroom clearance
of not less than six feet four inches, measured vertically from the
nearest nosing to the nearest soffit.
E.
Landings. Between landings there shall be not more than 12 feet measured
vertically, nor less than two risers. Every platform shall be at least
as wide as the stairway, measuring in the direction of travel. Such
dimension need not exceed four feet.
F.
Doors opening into stairways. Whenever a door opens onto a stairway,
a platform shall be provided extending at least the full width of
the door in the direction of travel.
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.