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§ 1541.15
<br />DWELLING HOUSE CODE
<br />shall have all joints filled with mortar. Hol-
<br />low masonry units, laid with cells vertical,
<br />shall have full mortar coverage of the face
<br />shells in both the horizontal and vertical
<br />joints; mortar joints between webs are not
<br />mandatory. Hollow masonry units, laid with
<br />cells horizontal, shall be bedded solidly in
<br />mortar and joints between contiguous shells
<br />shall be filled solid with mortar.
<br />1541.15 Bond.
<br />(a) Brick. In the required thickness of a
<br />brick masonry wall, there shall be a header
<br />course in every seventh course or less on
<br />both sides of the wall or there shall be at
<br />least one full length header in every lr/z
<br />square feet of wall surface and the distance
<br />between adjacent full-length headers shall
<br />not exceed 20 inches either vertically or
<br />horizontally.
<br />(b) Hollow or solid units. When two or
<br />more hallow units or solid units exceeding
<br />brick size are used to make up the required
<br />thickness of a wall, the inner and outer
<br />courses .shall be bonded at vertical inter-
<br />vals not exceeding 34 inches by lapping at
<br />least 4 inches or by lapping with units at
<br />least 50% greater in width than the units
<br />below at vertical intervals not exceeding 17
<br />inches.
<br />(c) Facing, Brick facing shall be bonded
<br />to walls of solid or hollow masonry units as
<br />required by subsections (a) and (b) of this
<br />Section 1541,15, Ashlar facing of either nat-
<br />ural or cast stone shall have at least 20%
<br />of the superficial area extending not less
<br />than 4 inches into the backing to form bond
<br />stones, which shall be uniformly distributed
<br />throughout the wall, Every projecting stone,
<br />and, except where alternate courses are full
<br />bond courses, every stone not a bond stone
<br />shall be securely anchored to the backing
<br />with substantial noncorrodible metal an-
<br />chors or ties with a cross section of not less
<br />than 02 square inches, There shall be at
<br />least one anchor or tie to each stone and not
<br />less than two anchors or ties for each stone
<br />more than 2 feet in length and 3 square feet
<br />in superficial area. Facing stones not over 12
<br />square feet in area shall have at least one
<br />anchor or tie to each 4 square feet of super-
<br />ficial face area. Facing may be, counted as
<br />part of the required wall thickness,
<br />(d) Veneer. Veneered .walls shall have
<br />the veneer tied into the backing either by a
<br />header for every 300. square inches of wall
<br />surface and extending at least 4 inches into
<br />the backing, or by substantial corrosion-re-
<br />sistant-wail anchors or ties with a cross sec-
<br />tion of not less than 0.02 square inches spaced
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<br />not farther apart than 17 inches vertically
<br />and 2 feet horizontally. The veneer shall not
<br />be counted as part of the required thickness
<br />of bearing walls and shall not exceed 35 feet
<br />in height above the adjoining ground.
<br />1541.16 Change in thickness.
<br />Except for permissible chases and re-
<br />cesses, walls shall not vary in thickness be-
<br />tween their lateral supports, When a change
<br />in thickness, due to minimum thickness re-
<br />quirements, occurs between floor levels the
<br />greater thickness shall be carried to the
<br />higher floor level. Where walls of hollow
<br />masonry units are decreased in thickness, a
<br />course of solid masonry shall be interposed
<br />between the wall section below such point
<br />and that next above.
<br />1541.17 Chases.
<br />Chases in masonry walls shall not be
<br />deeper than r/z the wall thickness nor longer
<br />than 4 feet horizontally and shall have at
<br />least 8 inches of masonry in back of the
<br />chases and between chases and jambs of
<br />openings. Chases not over 4 inches deep, 30
<br />inches wide and 24 inches high, maybe built
<br />in 8-inch walls, provided that chases below
<br />windows may equal the width of the opening
<br />above. The back of such chases in exterior
<br />walls shall be pargeted with r/z" of a 1: 2 mix
<br />cement mortar or otherwise waterproofed
<br />and insulated,
<br />1541.18 Anchorage.
<br />Masonry walls that meet or intersect shall
<br />be securely bonded or anchored. Floors and
<br />roofs shall be securely anchored to masonry
<br />walls at intervals not exceeding 6 feet.
<br />Where the same thickness of masonry wall
<br />continues above the bearing, the end of all
<br />wood beams or joists entering masonry walls
<br />shall be cut to a bevel of one-half the depth
<br />of beam or joist, or 3 inches, whichever is
<br />less.
<br />1541.19 Openings.
<br />The masonry above openings shall be sup-
<br />ported by well buttressed arches or lintels of
<br />metal or masonry, plain or reinforced, which
<br />shall bear on the wall at each end for not
<br />less than 4 inches:. Timber centering for
<br />arches may remain in place, provided the
<br />opening is riot over 4 feet wide and the tim-
<br />ber at each. end bears on the wall fora dis-
<br />tance not exceeding 2 inches.
<br />1541.20 Freezing.
<br />All masonry shall.' be protected against
<br />freezing" for at least ~ 24 hours after laying.
<br />No masonry shall be built - -upon :frozen
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<br />Interior li'inish and Assemblies
<br />§ 1579.14
<br />of lr/4 inches for r/z inch lath and 13/4 inches
<br />for 1 inch thickness of lath, shall be spaced
<br />not more than 3 inches apart at each stud or
<br />nailing member.
<br />(b) Freedom from moisture. Precaution
<br />shall be taken so that insulating board lath
<br />shall not be moistened during, prior to, or
<br />after application.
<br />(c) Installation. Lath shall be applied
<br />with long edges at right angles to the fram-
<br />ing or furring strips. End joints shall be
<br />centered on framing and the vertical joints
<br />or ends of each course of lath shall be stag-
<br />geredwith the points of the preceding course.
<br />(d) Reinforcement. All outside corners
<br />shall be reinforced with metal corner beads.
<br />All re-entrant angles shall be reinforced with
<br />standard expanded metal lath strips, not less
<br />than 6 inches square, bent into the angle and
<br />secured in place by nailing. All joints be-
<br />tween frame and masonry construction shall
<br />be reinforced with 6 inch strips of expanded
<br />metal lath. Expanded metal lath strips, 3
<br />inches wide and not less than 8 inches long,
<br />shall be applied diagonally at corners of door
<br />and window openings.
<br />1579.10 Gypsum lath.
<br />(a) Quality, size and thickness. Gypsum
<br />board lath shall conform in quality to ASTM
<br />C37. Standard size, 16" or 24" x 48", shall
<br />be used with a minimum thickness of 3/s inch
<br />for maximum stud or joist spacing of 16
<br />inches o.c. and r/z inch thickness for stud or
<br />joist spacing of 24 inches o.c.
<br />(b) Nailing. Gypsum lath shall be se-
<br />curely nailed to wood supports with blue
<br />plasterboard nails having 5/16 inch flat-
<br />heads and 1r/s inch long for 3/s inch thickness
<br />and lr/4 inch long for r/z inch thickness of
<br />lath. For stud or joist spacing of 16 inches,
<br />the nails shall be approximately 5 inches on
<br />center and for stud or joist spacing in excess
<br />of 16 inches the nails shall be approximately
<br />4 inches on center. The nails shall be driven
<br />with the underside of the head flush with the
<br />face of the lath and shall not be closer than
<br />3/a inch from edges or.ends.
<br />(c) Installation. Gypsum lath shall be ap-
<br />plied with its face side out and with the long
<br />dimension at right angles to the framing
<br />members. On walls, the end joint shall be
<br />made to fall on different supports in alternate
<br />courses. On ceilings, end joints shall either
<br />be staggered as for side walls, or the lath
<br />shall be erected so that end joints are made
<br />continuously on one support. -In the latter
<br />case, the continuous joints shall be covered
<br />with 3 inch wide strips of metal lath and the
<br />long or edge joints shall be offset or stag-
<br />gered. In all cases, the lath shall be butted
<br />together.
<br />(d) Cornerite. Cornerite shall be pro-
<br />vided at all interior angles and shall be
<br />fastened only sufficiently to retain position
<br />during plastering.
<br />(e) Metal supports. Gypsum lath shall be
<br />attached to horizontal or vertical metal sup-
<br />ports by means of special clips approved by
<br />the Building Official.
<br />1579.11 Inspection of lathing and furring.
<br />No plaster shall be applied until the lath-
<br />ing and furring has been inspected and ap-
<br />proved by the Building Official.
<br />1579.12 Plastering materials.
<br />All gypsum, lime, sand and other ingre-
<br />dients.used in plastering, their proportions
<br />and preparation shall conform to ASA A42.1,
<br />except that materials conforming with any
<br />of the following applicable standard specifi-
<br />cations shall also be deemed as acceptable
<br />good practice:
<br />Gypsum Plaster
<br />Keene's Cement
<br />Portland Cement
<br />Plastering
<br />Hydrated Lime
<br />Lime Putty,
<br />Preparation of
<br />Sand for Plaster
<br />ASTM C28
<br />ASTM C61
<br />ASA A42.3
<br />ASTM C6, C206, C207
<br />ASTM C5
<br />ASTM C35
<br />1579.13 Number of plaster coats required.
<br />Plaster applied on metal or wire lath shall
<br />be three-coat work. Plaster applied on wood
<br />lath, masonry, gypsum lath, or fiber insula-
<br />tion lath, shall be not less than two-coat
<br />work. Lime plastering on wood lath shall
<br />be three-coat work.
<br />1579.14 Lime plastering proportions.
<br />(a) Scratch (fast) coat. When lime plas-
<br />ter is applied in three-coat work, the first
<br />coat on metal or wire lath, or wood lath, shall
<br />be composed of not less than 1 volume of
<br />lime putty to 3 volumes of plastering sand,
<br />and not less than 71/z pounds of hair or fiber
<br />per cubic yard of mortar.
<br />(b) Base coat (2-coat work} or brown
<br />coat (3-coat work) . The first (base). coats of
<br />two-coat work and the second (brown) coat
<br />of three-coat work shall be, composed of not
<br />less than 1 volume of lime putty to 3 volumes
<br />of plastering sand and'.not less than 3r/z
<br />pounds of hair or fiber per cubic yard of mor-
<br />tar.
<br />(c) Admixtures. Portland cement or
<br />Keene's cement or other cementitious mate-
<br />rial approved by the Building Official may
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