City of Watertown, WI Construction Standards

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]

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.

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

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.

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.

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]

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.

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.

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.

Pilasters.

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.

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.

Girder pockets. Provide four-inch end bearing for girder. Provide one-half-inch air space between pocket and sides and end of wood girder.

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.

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.

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]

Foot drain tile.

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.

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.

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.

§ 253-28 Masonry chimneys.

Masonry chimneys. Masonry chimneys shall be constructed gastight and shall bear on masonry or concrete foundations.

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.

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.

Chimney cap. Chimney cap shall be provided to form wash from flue to outside edge of chimney; minimum thickness at outside edge: two inches.

Thimbles. Thimbles and cleanout doors shall be built in at the time chimney is constructed.

Cleanout doors. Every chimney shall be provided with a cleanout opening equipped with a metal cleanout door and frame.

Framing around chimney. Wood lath, furring or framing shall be placed not less than two inches from any chimney.

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.

§ 253-29 Fireplaces.

Smoke chamber, dampers, etc. Smoke chamber and damper shall be installed in all fireplaces.

Ash dump, when provided, shall empty into concrete or masonry chamber provided with metal cleanout door.

Lining shall be fire brick or other acceptable material.

Hearth. Support on masonry or concrete. Projection from chimney breast at least 16 inches. Width to be at least 16 inches wider than fireplace opening.

§ 253-30 Frame walls.

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.

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.

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.

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.

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.

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.

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.

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.

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:

Wood not less than 5/8 inch thick.

Approved fiber board not less than 7/16 inch thick.

Approved gypsum sheathing not less than 1/2 inch thick.

(4)

Approved plywood not less than 5/16 inch thick.

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.

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.

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.

§ 253-31 Masonry veneer on frame construction.

Thickness.

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.

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.

Flashing. Flashing shall be installed where necessary to prevent moisture from penetrating behind the wall.

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.

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.

§ 253-32 Stucco on frame construction.

Flashing. Flashing or other measures adequate to prevent penetration of moisture behind the stucco surface shall be used where necessary.

Back plastering. Back plastering shall be required where sheathing or its equivalent is omitted.

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.

§ 253-33 Wood framing.

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.

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.

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.

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.

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.

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.

Floor joist bridging.

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.

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.

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.

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.

§ 253-34 Concrete slab floors.

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:

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.

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.

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.

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.

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.

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.

§ 253-35 Ceiling and roof construction.

Roof framing. Roofs shall be so framed and tied into framework and supporting walls as to form an integral part of the whole building.

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]

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.

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.

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.

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.

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.

Roof trusses. If built-up roof trusses are used, they shall be of the size and space according to the manufacturer's specifications.

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.

Spans for ceiling joist.

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.