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§24-01 Exterior Veneering Materials.*
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(a) Scope. These rules are supplementary and additional to the requirements pertaining to exterior veneering materials not exceeding 2" in thickness, so as to provide for the sufficiency of attaching and anchoring mediums on such exterior veneers in accordance with the intent of the Administrative Building Code as outlined in § C26-3.0. They shall apply to veneering materials of metal, cement-asbestos, precast or natural stone, marble, ceramic, tile, concrete masonry units, glass sheets, glass block, plastic materials and other veneering materials, as may be approved by the Board. Note: These rules shall not apply to interior veneering materials. Extracts from the Administrative Building Code contained herein in small type have been assigned decimal rule numbers for convenient reference only and are not to be construed as rules.
(1) These rules shall apply to all materials used as exterior veneers of a thickness not exceeding two inches, bonded or unbonded, and with or without air spaces between the veneer and the supporting surface.
(2) Veneer materials shall not be credited with contributing to the total wall thickness, the stress resisting sections, or to the fire resistive value of the composite construction unless specifically approved by the Board for any given combination of materials.
(3) Veneer materials shall not be used to support vertical loads other than the veneering material above unless permitted otherwise as provided for in §24-01(b)3(3). Where openings occur the veneer shall be supported by substantial lintels of incombustible materials.
(4) All joints between masonry veneer materials shall be filled flush with mortar or approved mastic cement. Around wall openings the joints between the veneer and backing material shall be filled flush with similar materials. Gypsum shall not be used in veneer exposed to the weather except for temporary tacking and supplementary to the anchorage and cement mortar requirements set forth in these rules.
(5) All rosettes, toggle or expansion belts, metal reinforcements, bolts, clips, tie wires and supports shall be of non-corroding metal and of a type and for uses as may be approved by the Board.
(6) Veneering material shall not be placed over existing veneering material.
(7) Veneering when placed on a structure shall not encroach beyond the building line.
(8) Before attaching veneering materials to any surface, the soundness of structural members shall be examined by exposing the structural members and when found necessary, reinforcement or replacement of structural members shall be made to the satisfaction of the borough superintendent.
(9) Signs shall be so hung that their weight shall not bear on the veneering material and shall be supported by grounds set in the supporting wall.
(10) Veneering materials used above the first floor shall be installed in a manner permitting Fire Department access to each floor by means of existing or new windows or readily accessible access panels installed as provided in § C26-550.1d.
(11) Where openings occur in a wall, the veneer shall be supported by a structural member of incombustible material.
(12) All masonry walls shall be cleaned of dust and dampened before stone, marble, precast concrete units, tile or terra cotta is applied.
(c) Metal veneers.
(1) Metal veneers shall be of non-ferrous materials or of steel sheets protected on all sides by porcelain enamel or other approved corrosion resistant surfacing.
(2) Metal veneers shall be securely attached to the supporting construction with approved noncorroding metal hangers, clips, ties, screws, or bolts, secured to the metal veneer in a manner approved by the Board for each specific veneering material, and spaced not more than 16" o.c. vertically and 24" o.c. horizontally. Veneer units exceeding 4 sq. ft. in area shall be attached to the construction at not less than four points, so distributed as to render adequate attachment to the supporting construction.
(3) Where allowed to be used all corrosive supports for metal veneers shall be adequately protected from the effects of the elements by painting with approved paint, galvanizing or other equivalent means. Where the use of wood is permissible all wood used with metal veneers shall be impregnated with creosote or other approved preservative material.
(4) The joints and edges of all metal veneers shall be caulked or painted with approved waterproofing materials or other approved equivalent methods of providing resistance against moisture penetration.
(5) The height of walls veneered with metal units on walls other than panel or enclosure walls shall be not more than 40 ft. above the foundations.
(d) Precast or natural stone, marble, structural clay, ceramic and porcelain tile, terra cotta and precast concrete units.
(1) Veneered Wall (§ C26-157.0). The term "veneered wall" shall mean a wall with a masonry facing which is attached to, but not bonded so as to form an integral part of, the wall for purposes of load bearing and stability.
(2) Anchorage for veneered masonry walls (§ C26-437.0). When masonry walls are veneered with brick, architectural terra cotta, stone or other masonry, the material shall be securely tied into the backing with the equivalent of the following minimum anchorage requirements:
(i) For anchorage of brick veneering on masonry, one substantial non-corroding metal wall tie for each three hundred square inches of wall surface.
(ii) For anchorage of architectural terra cotta and other moulded units on masonry, one non-corroding metal anchor at least equal to five-sixteenths of an inch round or one-eighth of an inch by three-quarters of an inch flat in sectional area to each piece and two or more such anchors to all pieces over 18 inches in length or more than three hundred square inches in superficial area, except where such architectural terra cotta facing is bonded and completely filled with the brick backing.
(iii) For anchorage of stone veneering on masonry, one non-corroding anchor at least three-sixteenths of an inch by one inch flat, or its equivalent in cross sectional area, to each piece over one-half of a square foot in face area and at least two anchors to all pieces over 24 inches in length or more than four hundred square inches in superficial area.
(3) For slabs of natural stone or marble which are tough and hard and over 2 square feet and up to 4 square feet in area there shall be at least three anchors, from 4 square feet to 12 square feet, at least four anchors, from 12 square feet to 20 square feet at least six anchors and on slabs exceeding 20 square feet, anchors shall be provided at the rate of one anchor for each three square feet of area. All anchors shall be seated in cement mortar in a suitable hole sunk in masonry backing. Such anchors shall be of non-corrosive metal not less than 1/8" in diameter.
(4) When veneering is used in a continuous wall more than 25 feet in length without openings, suitable vertical expansion joints shall be provided at approximately 25 foot intervals through the entire height of the veneer.
(5) Thickness and height of veneered walls (§ C26-438.0). In all cases the veneering shall be excluded in calculating the bearing wall thickness and the required thickness of the wall. The maximum height of veneering on walls, other than panel or enclosure walls, shall be forty feet above the foundations.
(6) Veneered wood frame structures (§ C26-439.0). Wood frame structures may be veneered with masonry laid up in cement or cement-lime mortar. Such veneer shall be anchored to the frame by non-corroding metal ties equivalent to the following minimum requirements:
(i) For anchorage of brick veneer on frame structures, one wall tie to every 160 square inches of wall area.
(ii) For anchorage of stone, architectural terra cotta and other moulded units on frame structures, one spike anchor or two wall ties to every two hundred sixty square inches of wall area.
(iii) It shall be unlawful to use such veneer on frame structures above a maximum height of 35 ft. above the foundation; it shall be unlawful also, to use such veneer on structures having more than two stories and a gable. The veneer shall be directly supported on the foundation.
(iv) Frame structures veneered with masonry shall be considered to be in a different class from masonry structures. It shall be unlawful to attribute any structural strength to the veneer.
(7) Veneer units in this group shall be of approved type and not be greater than 2 in. in thickness. The surface bond of veneer units with the scored parging shall be adequately scored or provided with equivalent keys to obtain adequate anchorage. In addition to the attachment herein required, the anchorage requirements of § C26-437.0 shall be complied with. Equivalent substitute methods of anchorage consisting of non-corroding pin and rosette or a continuous angle or anchor bolts secured to the reinforcement within the veneer may be used when approved by the Board for any specific veneering material.
(8) The parging material in which veneer units are embedded shall consist of a portland cement mortar of 1:2 mix, 1 part of approved portland cement to two parts of screened sand passing through a 20 mesh screen not less than 3/4 in. thick and reinforced with 4 in. mesh (13 gauge) galvanized wire reinforcement or equivalent reinforcing. Such reinforcement to be secured to the masonry or concrete wall with approved non-corroding anchors at the rate prescribed in § C26-437.0. When the supporting wall is of wood framework, approved paper backed wire lath or other approved material may be used when attached to the wood framework as provided in § C26-459.0h, provided the weight of the veneering materials is carried on an incombustible base. The parged surface shall be trawled to a plane surface and then scratched to receive the setting bed. The setting bed of not less than 3/8" thick shall not be applied until the scratched parged surface is set. Prior to parging masonry on concrete surfaces, such walls shall be thoroughly wetted prior to the application of the parging mortar.
(9) Waterproofing material if used in mortar shall be of approved type.
(10) The base for supporting veneers shall be of suitable incombustible materials.
(11) All veneer units used in Class 1, 2 and 3 buildings exceeding 20 ft. in height, regardless of thickness, shall be attached to the scored parged surface by mechanical anchorage as provided in § C26-437.0, pars. 1, 2, 3 and shall have lugs, keys or equivalent scoring of the backside of the veneer unit or supported on relieving shelf angles at each story level.
(e) Glass veneer on the exterior of structures may be used only in accordance with the provisions of this title and the rule of the Board.
(1) Minimum thickness (§ C26-545.0). The minimum thickness of glass veneer shall be eleven-thirty-seconds of an inch, except where glass veneer extends within 4 in., or less of the sidewalk level, the minimum thickness of that portion of the veneer below a level of four inches above the sidewalk at its point of intersection with the veneer shall be seven-sixteenths of an inch.
(2) Maximum area and dimensions (§ C26-546.0).
(i) The maximum area of a single section of glass veneer shall not exceed 10 sq. ft. in area when 15 ft. or less above the level of the sidewalk directly below shall not exceed 6 sq. ft. in area when more than 15 ft. above the level of the sidewalk directly below.
(ii) The maximum length of any section of glass veneer shall be 60 in.
(3) Edges (§ C26-547.0). All edges of each plate of glass veneer shall be ground square. It shall be unlawful to use mitred joints.
(4) Backing for glass veneer (§ C26-548.0). Glass veneer may be placed only against substantial, rigid, incombustible surfaces of true plane, plumb and straight. The backing shall in any case provide rigidity and stability equal to or greater than that provided by one-inch thick cement mortar on wire lath secured to studs spaced 12 in. or less on centers. It shall be unlawful to use wood backing surfaces, regardless of whether they are fireproofed.
(5) Setting of glass veneer (§ C26-549.0).
(i) Glass veneer shall be set only when the backing is thoroughly dry and after the application of a thorough and uniform bond coat of material approved by the board. The bond coat shall be such as to effectively seal the portions of the veneer backing and to insure against the absorption of the vital properties of the mastic cement.
(ii) Mastic cement approved by the board shall be applied to the back surface of each plate of the glass veneer, which veneer shall be applied to the backing with a substantial and uniform pressure over its entire area sufficient to flatten out the gobs of mastic cement to a thickness of between one-quarter of an inch and five-eighths of an inch. Sufficient mastic cement shall be applied to insure that at least 60 percent of the total area of the section is bonded to the backing.
(iii) The bond coat and the mastic cement shall be of one manufacture and shall be certified to be of such composition as to insure close affinity between the two materials.
(iv) Abutting edges of glass veneer shall be ground square and uniformly buttered with an approved pointing compound.
(v) Where glass veneer extends to the sidewalk surface each such section shall rest on two cushions of approved resilient material, one near the end of each such section or plate. Cushions shall be one-quarter of an inch or more in thickness. The joint between the bottom edge of the glass section and the top of the sidewalk shall be caulked with a waterproof compound.
(vi) Where the glass veneer is permitted to extend below the level of the sidewalk surface, an expansion joint of one-quarter of an inch or more shall be provided between the outer face of the glass veneer and the edge of the sidewalk. Such expansion joint space shall be filled with a resilient caulking compound from the level of the sidewalk surface to a depth at least 3/4 of an inch below such level.
(vii) Where glass veneer is applied at an elevation more than eight feet above the sidewalk surface, the mastic cement binding shall be supplemented by the use of metal clip angles of a design approved by the Board. Clips shall be located in each vertical or horizontal edge of each section of veneer and shall be secured through the backing directly into the wall behind by means of expansion bolts and in a manner satisfactory to the superintendent. Angle clips shall be two inches or more in length and shall be of at least No. 16 U.S. gauge, and shall be so designed as to furnish at least two-inch bearing support on each clip and shall hold the glass in a vertical plane independently of the mastic cement.
(viii) All horizontal joints shall be cushoined with pads of adhesive asphaltic tape which shall extend from the rear surface of the glass to one-eighth of an inch or less from the front surface. Horizontal joints shall be buttered with joint cement over the full depth of the joint, including the surface of the cushion tape.
(ix) Shelf angles of approved design shall be set at vertical intervals of 3 ft. or less, in all horizontal joints located 8 ft. or less above the sidewalk, except that, where there are show windows it shall be unnecessary to have shelf angles below the level of the tops of the show window bulkheads. Shelf angles shall be of a type approved by the board and shall be secured to the backing in a manner satisfactory to the superintendent.
(x) Where glass veneer is confined between non-resilient materials at ends, expansion shall be provided for by means of an expansion joint at each end of one-quarter of an inch or more throughout the entire height of the veneer.
(6) Clips required under § C26-549.0, subsection (g) shall be non-corroding and located in each vertical plane in horizontal edge of each section of veneer and shall be thoroughly secured through the backing by means of non-corroding toggle bolts or into the wall directly behind the glass veneer by means of non-corrodible expansion bolts at least 1 1/4" long.
(7) Shelf angles required under § C26-549.0, sub-section (i) shall be of non-corroding metal of a type approved by the Board and shall be thoroughly secured through the backing by means of non-corroding toggle bolts or into the wall directly behind the glass veneer by means of non-corroding expansion bolts at least 1 1/4" long.
(8) Glass veneer units shall be separated from each other and adjoining material by an expansion joint at least 1/32" wide. Between the bolts and the veneer units there shall be a clearance of 1/64". All expansion joints shall be filled with an approved waterproofing mastic compound.
(9) Glass veneer material shall not be used any higher than 2 stories and not exceeding 35 ft. in height above the foundation of the structure.
(10) Exposed edges of glass veneer shall be flashed with non-corrodible sheet metal and caulked with an approved waterproofing mastic compound.
(11) All awning brackets shall be set so as to be free of contact with the glass veneer. Glass veneer above awning boxes shall be carried by a continuous steel angle attached to the wall by anchors.
(12) Signs shall be hung clear of the glass veneering material.
(f) Glass blocks (§ C26-550.1j.). Veneer or ashlar: Glass blocks may be used as exterior wall veneer under the rules of the Board. Note: Investigation has shown that glass block is not used as a veneer material in building construction and when uses of glass block are developed as veneer, the Board will then consider including in these rules the safe provisions for use.
(g) Veneering units of a type unprovided for in these rules, may be used, provided they are approved by the Board and are used in accordance with the limitations of the approval.