This chapter shall govern the materials, design, construction and quality of
masonry.
Masonry shall comply with the provisions of TMS 402, TMS 403 or TMS 404 as well as applicable requirements of this chapter.
The following notations are used in the chapter:
NOTATIONS.
db | = | Diameter of reinforcement, inches (mm). |
Fs | = | Allowable tensile or compressive stress in reinforcement, psi (MPa). |
fr | = | Modulus of rupture, psi (MPa). |
f 'AAC | = | Specified compressive strength of AAC masonry, the minimum compressive strength for a class of AAC masonry as specified in ASTM C1386, psi (MPa). |
f 'm | = | Specified compressive strength of masonry at age of 28 days, psi (MPa). |
f 'mi | = | Specified compressive strength of masonry at the time of prestress transfer, psi (MPa). |
K | = | The lesser of the masonry cover, clear spacing between adjacent reinforcement, or five times db, inches (mm). |
Ls | = | Distance between supports, inches (mm). |
ld | = | Required development length or lap length of reinforcement, inches (mm). |
P | = | The applied load at failure, pounds (N). |
St | = | Thickness of the test specimen measured parallel to the direction of load, inches (mm). |
Sw | = | Width of the test specimen measured parallel to the loading cylinder, inches (mm). |
Second-hand
masonry units shall not be reused unless they conform to the requirements of new units. The units shall be of whole, sound materials and free from cracks and other defects that will interfere with proper laying or use. Old
mortar shall be cleaned from the unit before reuse.
Mortar for use in
masonry construction shall conform to Articles 2.1 and 2.6 A of TMS 602.
Portland cement mortars for installing ceramic wall and floor tile shall comply with ANSI A108.1A and ANSI A108.1B and be of the compositions indicated in Table 2103.2.3.
TABLE 2103.2.3
CERAMIC TILE MORTAR COMPOSITIONS
LOCATION | MORTAR | COMPOSITION |
Walls | Scratchcoat | 1 cement; 1/5 hydrated lime; 4 dry or 5 damp sand |
Setting bed and leveling coat | 1 cement; 1/2 hydrated lime; 5 damp sand to 1 cement 1 hydrated lime, 7 damp sand |
Floors | Setting bed | 1 cement; 1/10 hydrated lime; 5 dry or 6 damp sand; or 1 cement; 5 dry or 6 damp sand |
Ceilings | Scratchcoat and sand bed | 1 cement; 1/2 hydrated lime; 21/2 dry sand or 3 damp sand |
Premixed prepared Portland cement
mortars, which require only the
addition of water and are used in the installation of ceramic tile, shall comply with ANSI A118.1. The shear bond
strength for tile set in such
mortar shall be as required in accordance with ANSI A118.1. Tile set in dry-set Portland cement
mortar shall be installed in accordance with ANSI A108.5.
Latex-modified Portland cement thin-set
mortars in which latex is added to dry-set
mortar as a replacement for all or part of the gauging water that are used for the installation of ceramic tile shall comply with ANSI A118.4. Tile set in latex-modified Portland cement shall be installed in accordance with ANSI A108.5.
Ceramic tile set and grouted with chemical-resistant epoxy shall comply with ANSI A118.3. Tile set and grouted with epoxy shall be installed in accordance with ANSI A108.6.
Chemical-resistant furan
mortar and grout that are used to install ceramic tile shall comply with ANSI A118.5. Tile set and grouted with furan shall be installed in accordance with ANSI A108.8.
Modified epoxy-emulsion
mortar and grout that are used to install ceramic tile shall comply with ANSI A118.8. Tile set and grouted with modified epoxy-emulsion
mortar and grout shall be installed in accordance with ANSI A108.9.
Water-resistant organic adhesives used for the installation of ceramic tile shall comply with ANSI A136.1. The shear bond
strength after water immersion shall be not less than 40 psi (275 kPa) for Type I adhesive and not less than 20 psi (138 kPa) for Type II adhesive when tested in accordance with ANSI A136.1. Tile set in organic adhesives shall be installed in accordance with ANSI A108.4.
Portland cement grouts used for the installation of ceramic tile shall comply with ANSI A118.6. Portland cement grouts for tile work shall be installed in accordance with ANSI A108.10.
Grout shall comply with Article 2.2 of TMS 602.
Metal reinforcement and accessories shall conform to Article 2.4 of TMS 602. Where unidentified reinforcement is
approved for use, not less than three tension and three bending tests shall be made on representative specimens of the reinforcement from each shipment and
grade of reinforcing steel proposed for use in the work.
Masonry construction shall comply with the requirements of Sections
2104.1.1 through 2104.1.3 and with the requirements of either TMS 602 or TMS 604.
Masonry shall not be supported on wood girders or other forms of wood construction except as permitted in
Section 2304.12.
Unless structural support and anchorage are provided to resist the overturning moment, the center of gravity of projecting
masonry or molded
cornices shall lie within the middle one-third of the supporting
wall. Terra cotta and metal
cornices shall be provided with a structural frame of
approved noncombustible material anchored in an
approved manner.
A quality assurance program shall be used to ensure that the constructed masonry is in compliance with the approved construction documents.
The quality assurance program shall comply with the inspection and testing requirements of Chapter 17 and TMS 602.
The design of
masonry structures using
allowable stress design shall comply with Section 2106 and the requirements of Chapters 1 through 8 of TMS 402 except as modified by Sections 2107.2 through
2107.3.
As an alternative to Section 6.1.6.1.1, it shall be permitted to design lap splices in accordance with Section 2107.2.1.
The minimum length of lap
splices for reinforcing bars in tension or compression,
ld, shall be:
ld = 0.002db fs
(Equation 21-1)
For SI:
ld = 0.29
db fs
but not less than 12 inches (305 mm). The length of the lapped
splice shall be not less than 40 bar diameters.
where: |
db |
= |
Diameter of reinforcement, inches (mm). |
fs |
= |
Computed stress in reinforcement due to design loads, psi (MPa). |
In regions of moment where the design tensile stresses in the reinforcement are greater than 80 percent of the allowable steel tension stress,
Fs, the lap length of
splices shall be increased not less than 50 percent of the minimum required length, but need not be greater than 72
db. Other equivalent means of stress transfer to accomplish the same 50 percent increase shall be permitted. Where epoxy coated bars are used, lap length shall be increased by 50 percent.
Modify Section 6.1.6.1 as follows:
- 6.1.6.1 — Splices of reinforcement. Lap splices, welded splices or mechanical splices are permitted in accordance with the provisions of this section. Welding shall conform to AWS D1.4. Welded splices shall be of ASTM A706 steel reinforcement. Reinforcement larger than No. 9 (M #29) shall be spliced using mechanical connections in accordance with Section 6.1.6.1.3.
The design of masonry structures using strength design shall comply with Section 2106 and the requirements of Chapters 1 through 7 and Chapter 9 of TMS 402, except as modified by Sections 2108.2 through 2108.3.
Exception: AAC masonry shall comply with the requirements of Chapters 1 through 7 and Chapter 11 of TMS 402.
Modify the second paragraph of Section 6.1.5.1.1 as follows:
The required development length of reinforcement shall be determined by Equation (6-1), but shall be not less than 12 inches (305 mm) and need not be greater than 72 db.
Modify Sections 6.1.6.1.2 and 6.1.6.1.3 as follows:
- 6.1.6.1.2 — A welded splice shall have the bars butted and welded to develop not less than 125 percent of the yield strength, ƒy, of the bar in tension or compression, as required. Welded splices shall be of ASTM A706 steel reinforcement. Welded splices shall not be permitted in plastic hinge zones of intermediate or special reinforced walls.
- 6.1.6.1.3 — Mechanical splices shall be classified as Type 1 or 2 in accordance with Section 18.2.7.1 of ACI 318. Type 1 mechanical splices shall not be used within a plastic hinge zone or within a beam-column joint of intermediate or special reinforced masonry shear walls. Type 2 mechanical splices are permitted in any location within a member.
Empirically designed adobe
masonry shall conform to the requirements of Appendix A of TMS 402, except where otherwise noted in this section.
AMENDMENT
This section has been amended at the state or city level.
The use of empirical design of adobe masonry shall be limited as noted in Section A.1.2 of TMS 402. In buildings that exceed one or more of the limitations of Section A.1.2 of TMS 402, masonry shall be designed in accordance with the engineered design provisions of Section 2101.2 or the foundation wall provisions of Section 1807.1.5.
Section A.1.2.2 of TMS 402 shall be modified as follows:
- A.1.2.2 — Wind. Empirical requirements shall not apply to the design or construction of masonry for buildings, parts of buildings, or other structures to be located in areas where Vasd as determined in accordance with Section 1609.3.1 of the International Building Code of New York State exceeds 110 mph.
Adobe construction shall comply with this section and shall be subject to the requirements of this code for Type V construction, Appendix A of TMS 402, and this section.
Adobe units shall have an average compressive
strength of 300 psi (2068 kPa) when tested in accordance with ASTM C67. Five samples shall be tested and individual units are not permitted to have a compressive
strength of less than 250 psi (1724 kPa).
Adobe units shall have an average modulus of rupture of 50 psi (345 kPa) when tested in accordance with the following procedure. Five samples shall be tested and individual units shall not have a modulus of rupture of less than 35 psi (241 kPa).
A cured unit shall be simply supported by 2-inch-diameter (51 mm) cylindrical supports located 2 inches (51 mm) in from each end and extending the full width of the unit.
A 2-inch-diameter (51 mm) cylinder shall be placed at midspan parallel to the supports.
A vertical load shall be applied to the cylinder at the rate of 500 pounds per minute (37 N/s) until failure occurs.
The modulus of rupture shall be determined by the equation:
f r = 3 PLs /2 Sw (St 2)
(Equation 21-2)
where, for the purposes of this section only: |
Sw |
= |
Width of the test specimen measured parallel to the loading cylinder, inches (mm). |
fr |
= |
Modulus of rupture, psi (MPa). |
Ls |
= |
Distance between supports, inches (mm). |
St |
= |
Thickness of the test specimen measured parallel to the direction of load, inches (mm). |
P |
= |
The applied load at failure, pounds (N). |
Adobe units shall have a moisture content not exceeding 4 percent by weight.
Adobe units shall not contain more than three shrinkage cracks and any single shrinkage crack shall not exceed 3 inches (76 mm) in length or 1/8 inch (3.2 mm) in width.
Soil used for stabilized adobe units shall be chemically compatible with the stabilizing material.
A 4-inch (102 mm) cube, cut from a stabilized adobe unit dried to a constant weight in a ventilated oven at 212°F to 239°F (100°C to 115°C), shall not absorb more than 21/2 percent moisture by weight when placed on a constantly water-saturated, porous surface for seven days. Not fewer than five specimens shall be tested and each specimen shall be cut from a separate unit.
The allowable compressive stress based on
gross cross-sectional area of adobe shall not exceed 30 psi (207 kPa).
Bolt values shall not exceed those set forth in Table 2109.2.3.1.
TABLE 2109.2.3.1
ALLOWABLE SHEAR ON BOLTS IN ADOBE MASONRY
DIAMETER OF BOLTS (inches)
| MINIMUM EMBEDMENT (inches)
| SHEAR (pounds)
|
1/2 | — | — |
5/8 | 12 | 200 |
3/4 | 15 | 300 |
7/8 | 18 | 400 |
1 | 21 | 500 |
11/8 | 24 | 600 |
For SI: 1 inch = 25.4 mm, 1 pound = 4.448 N.
The minimum thickness of
exterior walls in one-
story buildings shall be 10 inches (254 mm). The
walls shall be laterally supported at intervals not exceeding 24 feet (7315 mm). The minimum thickness of interior
load-bearing walls shall be 8 inches (203 mm). The unsupported height of any
wall constructed of adobe units shall not exceed 10 times the thickness of such
wall.
Walls and partitions constructed of adobe units shall be supported by foundations or footings that extend not less than 6 inches (152 mm) above adjacent ground surfaces and are constructed of
solid masonry (excluding adobe) or
concrete. Footings and foundations shall comply with
Chapter 18.
Stabilized adobe units shall be used in adobe
walls for the first 4 inches (102 mm) above the finished first-floor elevation.
Adobe units shall not be used for isolated piers or columns in a load-bearing capacity.
Walls less than 24 inches (610 mm) in length shall be considered to be isolated piers or columns.
Exterior walls and interior
load-bearing walls constructed of adobe units shall have a continuous tie beam at the level of the floor or roof bearing and meeting the following requirements.
Concrete tie beams shall be 6 inches (152 mm) or more in depth and 10 inches (254 mm) or more in width.
Concrete tie beams shall be continuously reinforced with not fewer than two No. 4 reinforcing bars. The specified compressive
strength of
concrete shall be not less than 2,500 psi (17.2 MPa).
Wood tie beams shall be
solid or built up of lumber having a
nominal thickness of not less than 1 inch (25 mm), and shall have a depth of not less than 6 inches (152 mm) and a width of not less than 10 inches (254 mm).
Joints in wood tie beams shall be spliced not less than 6 inches (152 mm).
Splices shall not be allowed within 12 inches (305 mm) of an opening. Wood used in tie beams shall be
approved naturally
decay-resistant or
preservative-treated wood.
Exterior walls constructed of unstabilized adobe units shall have their exterior surface covered with not fewer than two coats of Portland
cement plaster having a minimum thickness of
3/
4 inch (19.1 mm) and conforming to ASTM C926. Lathing shall comply with ASTM C1063. Fasteners shall be spaced at 16 inches (406 mm) on center maximum. Exposed wood surfaces shall be treated with an
approved wood preservative or other protective coating prior to lath application.
Lintels shall be considered to be structural members and shall be designed in accordance with the applicable provisions of
Chapter 16.
The
construction documents shall describe in sufficient detail the location, size and construction of
masonry fireplaces. The thickness and characteristics of materials and the clearances from
walls, partitions and ceilings shall be indicated.
Footings for
masonry fireplaces and their
chimneys shall be constructed of
concrete or
solid masonry not less than 12 inches (305 mm) thick and shall extend not less than 6 inches (153 mm) beyond the face of the
fireplace or foundation
wall on all sides. Footings shall be founded on natural undisturbed earth or engineered fill below frost depth. In areas not subjected to freezing, footings shall be not less than 12 inches (305 mm) below finished
grade.
Cleanout openings, located within foundation
walls below fireboxes, where provided, shall be equipped with ferrous metal or
masonry doors and frames constructed to remain tightly closed, except when in use. Cleanouts shall be accessible and located so that ash removal will not create a hazard to combustible materials.
Vertical reinforcement shall be placed enclosed within
1/
4-inch (6.4 mm) ties or other reinforcing of equivalent
net cross-sectional area, spaced not to exceed 18 inches (457 mm) on center in
concrete; or placed in the
bed joints of unit
masonry at not less than every 18 inches (457 mm) of vertical height. Two such ties shall be provided at each bend in the vertical bars.
Masonry fireplaces and foundations shall be anchored at each floor, ceiling or roof line more than 6 feet (1829 mm) above grade with two 3/16-inch by 1-inch (4.8 mm by 25 mm) straps embedded not less than 12 inches (305 mm) into the chimney. Straps shall be hooked around the outer bars and extend 6 inches (152 mm) beyond the bend. Each strap shall be fastened to not fewer than four floor joists with two 1/2-inch (12.7 mm) bolts.
Masonry fireboxes shall be constructed of
solid masonry units,
hollow masonry units grouted
solid, stone or
concrete. Where a lining of firebrick not less than 2 inches (51 mm) in thickness or other
approved lining is provided, the minimum thickness of back and sidewalls shall each be 8 inches (203 mm) of
solid masonry, including the lining. The width of
joints between firebricks shall be not greater than
1/
4 inch (6.4 mm). Where a lining is not provided, the total minimum thickness of back and sidewalls shall be 10 inches (254 mm) of
solid masonry. Firebrick shall conform to ASTM C27 or ASTM C1261 and shall be laid with medium-duty refractory
mortar conforming to ASTM C199.
Steel
fireplace units are permitted to be installed with
solid masonry to form a
masonry fireplace provided that they are installed according to either the requirements of their listing or the requirements of this section. Steel
fireplace units incorporating a steel firebox lining shall be constructed with steel not less than
1/
4 inch (6.4 mm) in thickness, and an air-circulating chamber that is ducted to the interior of the building. The firebox lining shall be encased with
solid masonry to provide a total thickness at the back and sides of not less than 8 inches (203 mm), of which not less than 4 inches (102 mm) shall be of
solid masonry or
concrete. Circulating air ducts employed with steel
fireplace units shall be constructed of metal or
masonry.
The firebox of a concrete or masonry fireplace shall have a minimum depth of 20 inches (508 mm). The throat shall be not less than 8 inches (203 mm) above the fireplace opening. The throat opening shall be not less than 4 inches (102 mm) in depth. The cross-sectional area of the passageway above the firebox, including the throat, damper and smoke chamber, shall be not less than the cross-sectional area of the flue.
Exception: Rumford fireplaces shall be permitted provided that the depth of the fireplace is not less than 12 inches (305 mm) and not less than one-third of the width of the fireplace opening, and the throat is not less than 12 inches (305 mm) above the lintel, and not less than 1/20 the cross-sectional area of the fireplace opening.
Masonry over a
fireplace opening shall be supported by a lintel of noncombustible material. The minimum required bearing length on each end of the
fireplace opening shall be 4 inches (102 mm). The
fireplace throat or damper shall be located not less than 8 inches (203 mm) above the top of the
fireplace opening.
Masonry fireplaces shall be equipped with a ferrous metal damper located not less than 8 inches (203 mm) above the top of the
fireplace opening. Dampers shall be installed in the
fireplace or at the top of the flue venting the
fireplace, and shall be operable from the room containing the
fireplace. Damper controls shall be permitted to be located in the
fireplace.
Smoke chamber
walls shall be constructed of
solid masonry units,
hollow masonry units grouted
solid, stone or
concrete. The total minimum thickness of front, back and sidewalls shall be 8 inches (203 mm) of
solid masonry. The inside surface shall be parged smooth with refractory
mortar conforming to ASTM C199. Where a lining of firebrick not less than 2 inches (51 mm) thick, or a lining of vitrified clay not less than
5/
8 inch (15.9 mm) thick, is provided, the total minimum thickness of front, back and sidewalls shall be 6 inches (152 mm) of
solid masonry, including the lining. Firebrick shall conform to ASTM C1261 and shall be laid with refractory
mortar conforming to ASTM C199. Vitrified clay linings shall conform to ASTM C315.
The inside height of the smoke chamber from the
fireplace throat to the beginning of the flue shall be not greater than the inside width of the
fireplace opening. The inside surface of the smoke chamber shall not be inclined more than 45 degrees (0.76 rad) from vertical where prefabricated smoke chamber linings are used or where the smoke chamber
walls are rolled or sloped rather than corbeled. Where the inside surface of the smoke chamber is formed by corbeled
masonry, the
walls shall not be corbeled more than 30 degrees (0.52 rad) from vertical.
Masonry fireplace hearths and hearth extensions shall be constructed of
concrete or
masonry, supported by noncombustible materials, and reinforced to carry their own weight and all imposed
loads. Combustible material shall not remain against the underside of hearths or hearth extensions after construction.
The minimum thickness of
fireplace hearths shall be 4 inches (102 mm).
The minimum thickness of hearth extensions shall be 2 inches (51 mm).
Exception: Where the bottom of the firebox opening is raised not less than 8 inches (203 mm) above the top of the hearth extension, a hearth extension of not less than 3/8-inch-thick (9.5 mm) brick, concrete, stone, tile or other approved noncombustible material is permitted.
Hearth extensions shall extend not less than 16 inches (406 mm) in front of, and not less than 8 inches (203 mm) beyond, each side of the
fireplace opening. Where the
fireplace opening is 6 square feet (0.557 m
2) or larger, the hearth extension shall extend not less than 20 inches (508 mm) in front of, and not less than 12 inches (305 mm) beyond, each side of the
fireplace opening.
Any portion of a
masonry fireplace located in the interior of a building or within the
exterior wall of a building shall have a clearance to combustibles of not less than 2 inches (51 mm) from the front faces and sides of
masonry fireplaces and not less than 4 inches (102 mm) from the back faces of
masonry fireplaces. The airspace shall not be filled, except to provide
fireblocking in accordance with
Section 2111.13.
Exceptions:
- Masonry fireplaces listed and labeled for use in contact with combustibles in accordance with UL 127 and installed in accordance with the manufacturer's instructions are permitted to have combustible material in contact with their exterior surfaces.
- Where masonry fireplaces are constructed as part of masonry or concrete walls, combustible materials shall not be in contact with the masonry or concrete walls less than 12 inches (306 mm) from the inside surface of the nearest firebox lining.
- Exposed combustible trim and the edges of sheathing materials, such as wood siding, flooring and drywall, are permitted to abut the masonry fireplace sidewalls and hearth extension, in accordance with Figure 2111.12, provided that such combustible trim or sheathing is not less than 12 inches (306 mm) from the inside surface of the nearest firebox lining.
- Exposed combustible mantels or trim is permitted to be placed directly on the masonry fireplace front surrounding the fireplace opening, provided that such combustible materials shall not be placed within 6 inches (153 mm) of a fireplace opening. Combustible material directly above and within 12 inches (305 mm) of the fireplace opening shall not project more than 1/8 inch (3.2 mm) for each 1-inch (25 mm) distance from such opening. Combustible materials located along the sides of the fireplace opening that project more than 11/2 inches (38 mm) from the face of the fireplace shall have an additional clearance equal to the projection.
For SI: 1 inch = 25.4 mm
FIGURE 2111.12
ILLUSTRATION OF EXCEPTION TO FIREPLACE CLEARANCE PROVISION
All spaces between
fireplaces and floors and ceilings through which
fireplaces pass shall be fireblocked with noncombustible material securely fastened in place. The
fireblocking of spaces between wood joists, beams or headers shall be to a depth of 1 inch (25 mm) and shall only be placed on strips of metal or metal lath laid across the spaces between combustible material and the
chimney.
Factory-built or
masonry fireplaces covered in this section shall be equipped with an exterior air supply to ensure proper fuel combustion unless the room is mechanically ventilated and controlled so that the indoor pressure is neutral or positive.
Exterior combustion air ducts for factory-built
fireplaces shall be
listed components of the
fireplace, and installed according to the
fireplace manufacturer's instructions.
Listed combustion air ducts for
masonry fireplaces shall be installed according to the terms of their listing and manufacturer's instructions.
The exterior air intake shall be capable of providing all combustion air from the exterior of the
dwelling. The exterior air intake shall not be located within a garage,
attic,
basement or crawl space of the
dwelling nor shall the air intake be located at an elevation higher than the firebox. The exterior air intake shall be covered with a corrosion-resistant screen of
1/
4-inch (6.4 mm) mesh.
Unlisted combustion air ducts shall be installed with a minimum 1-inch (25 mm) clearance to combustibles for all parts of the duct within 5 feet (1524 mm) of the duct outlet.
The combustion air passageway shall be not less than 6 square inches (3870 mm
2) and not more than 55 square inches (0.035 m
2), except that combustion air systems for
listed fireplaces or for
fireplaces tested for emissions shall be constructed according to the
fireplace manufacturer's instructions.
The exterior air outlet is permitted to be located in the back or sides of the firebox chamber or within 24 inches (610 mm) of the firebox opening on or near the floor. The outlet shall be closable and designed to prevent burning material from dropping into concealed combustible spaces.
A
masonry heater is a heating appliance constructed of
concrete or
solid masonry, hereinafter referred to as "
masonry," which is designed to absorb and store heat from a
solid fuel fire built in the firebox by routing the exhaust gases through internal heat exchange channels in which the flow path downstream of the firebox includes flow in either a horizontal or downward direction before entering the
chimney and which delivers heat by radiation from the
masonry surface of the heater.
Masonry heaters shall be installed in accordance with this section and comply with one of the following:
- Masonry heaters shall comply with the requirements of ASTM E1602.
- Masonry heaters shall be listed and labeled in accordance with UL 1482 or EN 15250 and installed in accordance with the manufacturer's instructions.
The firebox floor of a
masonry heater shall be a minimum thickness of 4 inches (102 mm) of noncombustible material and be supported on a noncombustible footing and foundation in accordance with
Section 2113.2.
AMENDMENT
This section has been amended at the state or city level.
Combustible materials shall not be placed within 36 inches (914 mm) or the distance of the allowed reduction method from the outside surface of a
masonry heater in accordance with NFPA 211, Section 12.6, and the required space between the heater and combustible material shall be fully vented to
permit the free flow of air around all heater surfaces.
Exceptions:
- Where the masonry heater wall thickness is not less than 8 inches (203 mm) of solid masonry and the wall thickness of the heat exchange channels is not less than 5 inches (127 mm) of solid masonry, combustible materials shall not be placed within 4 inches (102 mm) of the outside surface of a masonry heater. A clearance of not less than 8 inches (203 mm) shall be provided between the gas-tight capping slab of the heater and a combustible ceiling.
- Masonry heaters listed and labeled in accordance with UL 1482 or EN 15250 and installed in accordance with the manufacturer's instructions.
Footings for
masonry chimneys shall be constructed of
concrete or
solid masonry not less than 12 inches (305 mm) thick and shall extend not less than 6 inches (152 mm) beyond the face of the foundation or support
wall on all sides. Footings shall be founded on natural undisturbed earth or engineered fill below frost depth. In areas not subjected to freezing, footings shall be not less than 12 inches (305 mm) below finished
grade.
For
chimneys up to 40 inches (1016 mm) wide, four No. 4 continuous vertical bars anchored in the foundation shall be placed in the
concrete between
wythes of
solid masonry or within the
cells of
hollow unit
masonry and grouted in accordance with
Section 2103.3. Grout shall be prevented from bonding with the flue liner so that the flue liner is free to move with thermal expansion. For
chimneys greater than 40 inches (1016 mm) wide, two additional No. 4 vertical bars shall be provided for each additional 40 inches (1016 mm) in width or fraction thereof.
Vertical reinforcement shall be placed enclosed within
1/
4-inch (6.4 mm) ties, or other reinforcing of equivalent
net cross-sectional area, spaced not to exceed 18 inches (457 mm) on center in
concrete, or placed in the
bed joints of unit
masonry, at not less than every 18 inches (457 mm) of vertical height. Two such ties shall be provided at each bend in the vertical bars.
Masonry chimneys and foundations shall be anchored at each floor, ceiling or roof line more than 6 feet (1829 mm) above grade with two 3/16-inch by 1-inch (4.8 mm by 25 mm) straps embedded not less than 12 inches (305 mm) into the chimney. Straps shall be hooked around the outer bars and extend 6 inches (152 mm) beyond the bend. Each strap shall be fastened to not less than four floor joists with two 1/2-inch (12.7 mm) bolts.
Masonry chimneys shall not be corbeled more than half of the
chimney's
wall thickness from a
wall or foundation, nor shall a
chimney be corbeled from a
wall or foundation that is less than 12 inches (305 mm) in thickness unless it projects equally on each side of the
wall, except that on the second
story of a two-
story dwelling, corbeling of
chimneys on the exterior of the enclosing
walls is permitted to equal the
wall thickness. The projection of a single course shall not exceed one-half the unit height or one-third of the unit bed depth, whichever is less.
The
chimney wall or
chimney flue lining shall not change in size or shape within 6 inches (152 mm) above or below where the
chimney passes through floor components, ceiling components or roof components.
Where a
masonry chimney is constructed with a fireclay flue liner surrounded by one
wythe of
masonry, the maximum offset shall be such that the centerline of the flue above the offset does not extend beyond the center of the
chimney wall below the offset. Where the
chimney offset is supported by
masonry below the offset in an
approved manner, the maximum offset limitations shall not apply. Each individual corbeled
masonry course of the offset shall not exceed the projection limitations specified in
Section 2113.5.
Chimneys shall extend not less than 2 feet (610 mm) higher than any portion of the building within 10 feet (3048 mm), but shall be not less than 3 feet (914 mm) above the highest point where the
chimney passes through the roof.
Masonry chimneys shall have a
concrete, metal or stone cap, sloped to shed water, a drip edge and a caulked bond break around any flue liners in accordance with ASTM C1283.
Where a spark arrestor is installed on a masonry chimney, the spark arrestor shall meet all of the following requirements:
- The net free area of the arrestor shall be not less than four times the net free area of the outlet of the chimney flue it serves.
- The arrestor screen shall have heat and corrosion resistance equivalent to 19-gage galvanized steel or 24-gage stainless steel.
- Openings shall not permit the passage of spheres having a diameter greater than 1/2 inch (12.7 mm) nor block the passage of spheres having a diameter less than 3/8 inch (9.5 mm).
- The spark arrestor shall be accessible for cleaning and the screen or chimney cap shall be removable to allow for cleaning of the chimney flue.
Where a
masonry or metal rain cap is installed on a
masonry chimney, the net free area under the cap shall be not less than four times the net free area of the outlet of the
chimney flue it serves.
Masonry chimneys shall be lined. The lining material shall be appropriate for the type of appliance connected, according to the terms of the appliance listing and the manufacturer's instructions.
Flue lining systems shall comply with one of the following:
- Clay flue lining complying with the requirements of ASTM C315.
- Listed chimney lining systems complying with UL 1777.
- Factory-built chimneys or chimney units listed for installation within masonry chimneys.
- Other approved materials that will resist corrosion, erosion, softening or cracking from flue gases and condensate at temperatures up to 1,800°F (982°C).
AMENDMENT
This section has been amended at the state or city level.
Flue lining systems for gas appliances shall be in accordance with the International Fuel Gas Code of New York State.
Flue lining and vent systems for use in
masonry chimneys with oil-fired appliances
approved for use with Type L vent shall be limited to flue lining systems complying with
Section 2113.11.1 and
listed chimney liners complying with UL 641 (see Section 2113.11.1.5 for marking).
When a flue is relined with a material not complying with
Section 2113.11.1, the
chimney shall be plainly and permanently identified by a
label attached to a
wall, ceiling or other conspicuous location adjacent to where the connector enters the
chimney. The
label shall include the following message or equivalent language: "This
chimney is for use only with (type or category of appliance) that burns (type of fuel). Do not connect other types of appliances."
Concrete and
masonry chimneys shall be lined with an
approved medium-duty refractory
brick not less than 4
1/
2 inches (114 mm) thick laid on the 4
1/
2-inch bed (114 mm) in an
approved medium-duty refractory
mortar. The lining shall start 2 feet (610 mm) or more below the lowest
chimney connector entrance.
Chimneys terminating 25 feet (7620 mm) or less above a
chimney connector entrance shall be lined to the top.
Concrete and
masonry chimneys for medium-heat appliances shall extend not less than 10 feet (3048 mm) higher than any portion of any building within 25 feet (7620 mm).
Chimneys for high-heat appliances shall be constructed with double
walls of
solid masonry units or of
concrete, each
wall to be not less than 8 inches (203 mm) thick with a minimum airspace of 2 inches (51 mm) between the
walls.
The inside of the interior
wall shall be lined with an
approved high-duty refractory
brick, not less than 4
1/
2 inches (114 mm) thick laid on the 4
1/
2-inch bed (114 mm) in an
approved high-duty refractory
mortar. The lining shall start at the base of the
chimney and extend continuously to the top.
Concrete and
masonry chimneys for high-heat appliances shall extend not less than 20 feet (6096 mm) higher than any portion of any building within 50 feet (15 240 mm).
Concrete and
masonry chimneys for high-heat appliances shall have
approved clearance from buildings and structures to prevent overheating combustible materials,
permit inspection and maintenance operations on the
chimney and prevent danger of burns to persons.
Clay flue liners shall be installed in accordance with ASTM C1283 and extend from a point not less than 8 inches (203 mm) below the lowest inlet or, in the case of fireplaces, from the top of the smoke chamber to a point above the enclosing walls. The lining shall be carried up vertically, with a maximum slope not greater than 30 degrees (0.52 rad) from the vertical.
Clay flue liners shall be laid in medium-duty nonwater-soluble refractory mortar conforming to ASTM C199 with tight mortar joints left smooth on the inside and installed to maintain an airspace or insulation not to exceed the thickness of the flue liner separating the flue liners from the interior face of the chimney masonry walls. Flue lining shall be supported on all sides. Only enough mortar shall be placed to make the joint and hold the liners in position.
Listed materials used as flue linings shall be installed in accordance with the terms of their listings and the manufacturer's instructions.
The space surrounding a chimney lining system or vent installed within a masonry chimney shall not be used to vent any other appliance.
Exception: This shall not prevent the installation of a separate flue lining in accordance with the manufacturer's instructions.
Where two or more flues are located in the same chimney, masonry wythes shall be built between adjacent flue linings. The masonry wythes shall be not less than 4 inches (102 mm) thick and bonded into the walls of the chimney.
Exception: Where venting only one appliance, two flues are permitted to adjoin each other in the same chimney with only the flue lining separation between them. The joints of the adjacent flue linings shall be staggered not less than 4 inches (102 mm).
AMENDMENT
This section has been amended at the state or city level.
Chimney flues shall not be smaller in area than the area of the connector from the appliance.
Chimney flues connected to more than one appliance shall be not less than the area of the largest connector plus 50 percent of the areas of additional
chimney connectors.
Exceptions:
- Chimney flues serving oil-fired appliances sized in accordance with NFPA 31.
- Chimney flues serving gas-fired appliances sized in accordance with the International Fuel Gas Code of New York State.
AMENDMENT
This section has been amended at the state or city level.
Flue sizing for chimneys serving fireplaces shall be in accordance with Section 2113.16.1 or 2113.16.2.
NoteFor SI: 1 inch = 25.4 mm, 1 square inch = 645 mm2.
FIGURE 2113.16
FLUE SIZES FOR MASONRY CHIMNEYS
TABLE 2113.16(1)
NET CROSS-SECTIONAL AREA OF ROUND FLUE SIZESa
FLUE SIZE, INSIDE DIAMETER (inches)
| CROSS-SECTIONAL AREA (square inches)
|
6 | 28 |
7 | 38 |
8 | 50 |
10 | 78 |
103/4 | 90 |
12 | 113 |
15 | 176 |
18 | 254 |
For SI: 1 inch = 25.4 mm, 1 square inch = 645.16 mm2.
- Flue sizes are based on ASTM C315.
TABLE 2113.16(2)
NET CROSS-SECTIONAL AREA OF SQUARE AND RECTANGULAR FLUE SIZES
FLUE SIZE, OUTSIDE NOMINAL DIMENSIONS (inches)
| CROSS-SECTIONAL AREA (square inches)
|
4.5 × 8.5 | 23 |
4.5 × 13 | 34 |
8 × 8 | 42 |
8.5 × 8.5 | 49 |
8 × 12 | 67 |
8.5 × 13 | 76 |
12 × 12 | 102 |
8.5 × 18 | 101 |
13 ×13 | 127 |
12 × 16 | 131 |
13 × 18 | 173 |
16 × 16 | 181 |
16 × 20 | 222 |
18 × 18 | 233 |
20 × 20 | 298 |
20 × 24 | 335 |
24 × 24 | 431 |
For SI: 1 inch = 25.4 mm, 1 square inch = 645.16 mm2.
The minimum
net cross-sectional area of the flue shall be determined in accordance with
Figure 2113.16. A flue size providing not less than the equivalent
net cross-sectional area shall be used. Cross-sectional areas of clay flue linings are as provided in Tables
2113.16(1) and
2113.16(2) or as provided by the manufacturer or as measured in the field. The height of the
chimney shall be measured from the firebox floor to the top of the
chimney flue.
Inlets to
masonry chimneys shall enter from the side. Inlets shall have a thimble of fireclay, rigid refractory material or metal that will prevent the connector from pulling out of the inlet or from extending beyond the
wall of the liner.
Cleanout openings shall be provided within 6 inches (152 mm) of the base of each flue within every masonry chimney. The upper edge of the cleanout shall be located not less than 6 inches (152 mm) below the lowest chimney inlet opening. The height of the opening shall be not less than 6 inches (152 mm). The cleanout shall be provided with a noncombustible cover.
Exception: Chimney flues serving masonry fireplaces, where cleaning is possible through the fireplace opening.
Any portion of a masonry chimney located in the interior of the building or within the exterior wall of the building shall have a minimum airspace clearance to combustibles of 2 inches (51 mm). Chimneys located entirely outside the exterior walls of the building, including chimneys that pass through the soffit or cornice, shall have a minimum airspace clearance of 1 inch (25 mm). The airspace shall not be filled, except to provide fireblocking in accordance with Section 2113.20.
Exceptions:
- Masonry chimneys equipped with a chimney lining system listed and labeled for use in chimneys in contact with combustibles in accordance with UL 1777, and installed in accordance with the manufacturer's instructions, are permitted to have combustible material in contact with their exterior surfaces.
- Where masonry chimneys are constructed as part of masonry or concrete walls, combustible materials shall not be in contact with the masonry or concrete wall less than 12 inches (305 mm) from the inside surface of the nearest flue lining.
- Exposed combustible trim and the edges of sheathing materials, such as wood siding, are permitted to abut the masonry chimney sidewalls, in accordance with Figure 2113.19, provided that such combustible trim or sheathing is not less than 12 inches (305 mm) from the inside surface of the nearest flue lining. Combustible material and trim shall not overlap the corners of the chimney by more than 1 inch (25 mm).

FIGURE 2113.19
ILLUSTRATION OF EXCEPTION THREE CHIMNEY CLEARANCE PROVISION
All spaces between
chimneys and floors and ceilings through which
chimneys pass shall be fireblocked with noncombustible material securely fastened in place. The
fireblocking of spaces between wood joists, beams or headers shall be self-supporting or be placed on strips of metal or metal lath laid across the spaces between combustible material and the
chimney.
The design of dry-stack
masonry structures shall comply with the requirements of Chapters 1 through 8 of TMS 402 except as modified by Sections 2114.2 through
2114.5.
Dry-stack
masonry shall be of adequate
strength and proportions to support all superimposed
loads without exceeding the allowable stresses listed in
Table 2114.4. Allowable stresses not specified in
Table 2114.4 shall comply with the requirements of Chapter 8 of TMS 402.
For SI: 1 pound per square inch = 0.006895 MPa.
Construction of dry-stack
masonry shall comply with ASTM C946.