A. General:
1. Materials: See section 8-3-4 of this chapter.
2. Mortar: Masonry below grade: Portland cement mortar consisting of 1 part Portland cement and 3 parts sand by volume; lime, not more than 25% of the cement by volume may be added.
All other masonry: Portland cement mortar (see above) or cement-lime mortar, consisting of 1 part Portland cement, prepared masonry cement mortars; 1 part masonry cement, 3 parts sand by volume, with no other materials added other than sand and water. Retempering of mortar not permitted.
3. Joints: Maximum thickness: 1/2", with all joints to be uniform in thickness. Solid masonry units: Fill joints solid. Hollow masonry units: No through mortar joints. Point all joints solid both sides of wall. Weather or tool outside and exposed inside joints unless otherwise acceptable to the building officer.
4. Bonding: Brick masonry: Header course consisting of alternate through header and stretcher every seventh course, or 1 through header in every 240 square inches, uniformly placed throughout wall. Rubble stone masonry: Bond stones at least 4" thicker than other stones. Minimum: 20% of wall area. Stagger vertical joints. Intersecting concrete and masonry walls: bond together.
5. Closed Cell Hollow Units: Use for rough openings, corners and wall intersection. Filling exposed ends of cells not permitted.
6. Protection: Provide frost protection, acceptable to building officer, when temperature falls below freezing, except that no masonry work shall be done in temperatures below 20° Fahrenheit.
7. Loading: Allow sufficient time for strength of masonry to develop before subjecting to loads.
B. Masonry Unit Foundation Walls: (For cast in place concrete foundation walls, see subsection 8-3-5J of this chapter.)
1. General Materials: (See section 8-3-4 of this chapter.)
Walls supporting wood frame construction: Extend so that wood portion of wall is not less than 4" above adjoining outside finished grade.
Wall supporting masonry veneered wood frame: Extend foundation so that wood portion of wall is not less than 4" above outside finished grade.
Wall of hollow units: Cap with minimum of 4" of solid masonry, concrete, or fill upper course with concrete, or, use approved top course bearing block.
Concentrated loads: Under ends of girders bearing on hollow masonry unit foundation walls, support on minimum of 4" solid masonry or concrete, or, fill upper 2 courses with concrete.
2. Minimum Thickness: Not less than that of wall supported. Masonry unit walls, minimum thickness, 8", except when total height of foundation wall and masonry wall supported exceeds 30' at eaves and 35' at ridge in gable end, when minimum shall be 12". Rubble stone: 16".
3. Girder Pockets: Provide 4" end bearing for girder. For wood girder, leave 1/2" space each side.
4. Sill Anchor Bolts To Be Installed: Diameter: 1/2" minimum. Minimum length in masonry unit walls: 15". Provide washer under nuts on bolts. Spacing: Not more than 8' on center: minimum 2 bolts in each piece. Top 2 courses to be completely filled with concrete.
5. Anchorage For Intersection Walls And Slabs: Provide anchorage for concrete area walls with 1/2" dowel bars at 10" on center.
6. Chimney Foundations: Start at a level of lowest adjacent foundation wall footings.
7. Special Soil Conditions: If special or unforeseen soil conditions warrant, the building officer may require either reinforcement of wall or increased thickness.
C. Damp Proofing And Waterproofing:
1. Damp proof basement unit masonry walls on exterior side from finished grade to outside edge of footing using 1/2" thick Portland cement plaster coating, forming a cove at footing over which apply at least 1 heavy coat of undiluted hot tar, asphalt or compound, acceptable to the building officer. Not required where entire area is basementless.
2. Concrete walls cast in place: Apply at least 1 heavy coat of undiluted hot tar, asphalt or compound on exterior from finished grade to outside edge of footing acceptable to the building officer.
D. Piers:
1. Masonry piers supporting exterior walls acceptable only for open porches. Provide adequate girders for support of floor and wall loads between piers.
2. Materials: Masonry units or cast in place concrete (see section 8-3-4 of this chapter).
3. Minimum size in inches: Masonry: 12" x 12". Plain concrete: 10" x 10", or 8" in diameter if round.
4. Maximum spacing: Exterior wall piers supporting floor joists: 8' on center. Exterior wall piers in line parallel to joists and interior piers: 12' on center.
5. Minimum height above grade: 6".
6. When of hollow masonry units, cap with at least 4" solid masonry or concrete, or fill upper 2 courses with concrete (see subsection B1 of this section).
7. Sill anchor bolts, dowels or pier brackets to be installed.
E. Exterior Masonry Walls Above Grade:
1. Materials: Masonry or cast in place concrete (see section 8-3-4 of this chapter).
2. Minimum thickness: 8".
3. Maximum for 8" thickness: 22' from grade to eaves; or 30' from grade to ridge in gable ends. For greater heights, minimum thickness 12" except top 22".
a. In all cases the height cannot exceed 18 times the width of the block and/or wall without installing intermediate support at that height either by a floor system and/or ceiling roof combination.
b. The length cannot exceed 75 times the width of the block and/or wall without installing intermediate support at that length either by interior partitions and/or pilasters.
4. Backing, when used, solid or hollow masonry units, minimum thickness, bonded to facing: 4". Facing and backup bonded with masonry bond or other substantial ties (excluding sheet metal ties).
5. Furring, if necessary, when interior finish is applied. Not less than 1" wood strips. Spacing as permitted for interior finish (see section 8-3-13 of this chapter). Install horizontal furring strips at ceiling and floor to form fire stops and prevent convection. Exterior walls to be moisture proofed if plaster is applied directly thereon.
6. Lintels: Size to be determined by span in each case. No concentrated loads over nonreinforced lintels. Lintels may be precast concrete, brick reinforced, stone, masonry arch, steel, or wood (see section 8-3-24, appendix A, of this chapter). Minimum bearing: 4" in length on each end.
7. Rafters plate anchor bolts to be installed. Diameter, 1/2", minimum. Minimum length in masonry unit walls: 15". Poured concrete walls: 10". In masonry walls, washer and 3" square plate on bolts. Spacing not more than 8' on center.
8. Radiator recesses: Construct at time wall is built. Maximum recess depth: 4" in 8" walls; 8" in 12" walls. Back and side of recess to be waterproofed and insulated. Width under windows not greater than rough opening.
9. Vertical chases: Construct at time wall is built. Maximum length for chases, where wall thickness is 8" or less: 4'. Maximum chase depth: 4".
10. Horizontal chases: Not acceptable unless wall thickness is at least 4" greater than thickness required under subsection E2 of this section. Maximum depth: 4".
F. Masonry Veneer:
1. Minimum thickness: Brick: 33/4". Ashlar stone masonry: 4". Rubblestone masonry, uncoursed (field stone): 12". Mosaic or random: 12", coursed, one-story: 8"; over one-story: 12".
2. Masonry veneered wood frame construction: Veneer applied over sheathing with air space between.
Air space: 3/4" between masonry veneer and sheathing.
Base flashing: Saturated asphalt felt not less than 15 pounds per square or copper extending over top of foundation wall from outside face wall, and not less than 12" up on sheathing (base flashing may be omitted if foundation is offset at least 2"). Apply water resistant building paper, or saturated asphalt felt over sheathing; lap base flashing at least 4".
Bonding: Corrosion resisting metal ties spaced not more than 15" vertically and 32" on center horizontally. When other than wood board sheathing is used, secure ties through to studs with corrosion resisting nails of length sufficient to penetrate wood at least 1".
Lintels: Size to be determined by materials and span in each case; bearing at least 4"; arches permitted.
G. Cavity Walls:
1. Minimum thickness: Facing (outer leaf): 33/4". Backing (inner leaf): 33/4". (Total, with cavity: 10".)
2. Maximum height above grade for minimum thickness: 22' to eaves. 30' to ridge at gable ends.
3. Lay units with full flat bed and vertical joints.
4. Tie each square foot of facing to backing with approved rigid, corrosion resistant tie bars, at least 3/16" in diameter. Embed ties in horizontal joints. Also locate not more than 3' apart within 12" of perimeter of all openings. "Z" bars shall have 6" shank length and 3" legs bent to 90° angles. Ties used with hollow units with cells vertical shall be rectangular in shape.
5. Flash with a corrosion resistant metal sheet over tops of all openings, at window sills, and at bottom of cavity wall.
6. Provide weep holes along flashing. Keep cavity clear of mortar droppings.
H. Interior Masonry Walls:
1. Material: Masonry or cast in place concrete.
2. Pipe recesses: Construct at time walls are built.
3. Party and fire walls: Minimum thickness, cast in place concrete: 6". Masonry units: 8". Chases or recesses not permitted. Flat roofs: Extend above roof, flash and cap with stone, concrete, vitrified tile, or terra cotta. Under pitched roofs: Build masonry solid to underside of roof sheathing, unless carried above roof.
4. Bearing partitions: Minimum thickness: Plain concrete, 6". Masonry units, 8". Sections of walls with distance between opening 2' or less. Solid masonry reinforced concrete or, masonry arches, minimum, 4" bearing upon solid masonry at least 4" thick. Girder bearing: Solid masonry at least 8" thick.
5. Nonbearing partitions: Minimum thickness: 3". Lintels: Steel, reinforced concrete, or, masonry, or, masonry arches.
I. Chimneys:
1. Required; Exception: Provide masonry chimney except as provided in subsection I8 of this section. Separate flue required for each fireplace and heating appliance, unless combined flue is specifically approved by the building officer.
2. Materials: Solid masonry with footing of concrete cast in place, except as provided in subsection I8 of this section.
3. Effective Flue Area: At least as recommended by the manufacturer of equipment connected to chimney but in no case shall chimney flue be smaller in area than that of the area of the connector from the appliance. Minimum diameter for house heating flue, 8". For fireplace, type of flue: Round lined 1/12 of fireplace opening area but not less than 50 square inches. Square or rectangular lined 1/10 of fireplace opening area but not less than 64 square inches. Lined with firebrick or unlined 1/8 of fireplace opening area but not less than 100 square inches.
4. Chimney Linings, Withes, And Walls: Glazed fireclay flue lining required in all chimneys for liquid and solid fuels: When gas is used as fuel, provide flue lining of stainless steel, porcelain enameled iron, asbestos cement, or glazed fireclay lining or vitrified tile lining, bell and spigot type, bell end up, all with joints made with acid resisting mortar; provide drain to dispose of condensation. 2 flues may be grouped without withes provided joints of linings are staggered, 33/4" minimum thickness. Walls, minimum thickness, 33/4" in addition to lining.
5. Height Of Chimney: As recommended by equipment manufacturer, shall extend at least 3' above the adjacent roof, and at least 2' above any roof ridge within 10' thereof. If the height above the roof is more than 4 times the minimum dimension, the chimney shall be braced and anchored to the roof framing and not less than 3' above the ridge of the roof that the chimney penetrates and not less than 2' above the highest ridge within 15' of the chimney.
6. Cap Of Chimney: Cap of chimney to form wash from flue to outside edge, minimum thickness, 2".
7. Metal Thimbles And Cleanout Doors: Metal thimbles and cleanout doors to be built in at the time chimney is constructed.
8. Other Than Masonry: Chimneys, flues, and vents, other than masonry, may be used when approved by the National Board of Fire Underwriters for the kind of fuel to be used.
9. Factory Built Chimneys: Factory built chimneys and additional information, see 2006 international building code, section 2111.13.1 or current adoption.
J. Fireplace:
1. Smoke Chambers And Dampers: Smoke chambers and dampers required in all fireplaces.
2. Minimum Wall Thickness: 8", in addition to the lining.
3. Ash Dump: When provided, empty into concrete or masonry chamber provided with metal cleanout door.
4. Lining: Firebrick or other approved material.
5. Hearth: Support on masonry or concrete. Width: At least 8" wider than fireplace opening on each side. Material: Incombustible. Combined thickness of hearth and support: 6".
6. Fireplace Opening Lintel: Use brick arch, concrete, stone, or steel.
7. Facing: Masonry: no combustible material closer than 71/2" to fireplace opening.
8. Minimum Dimensions:
MINIMUM DIMENSIONS FOR FIREPLACES
Fireplace Component | Minimum Dimension |
Fireplace Component | Minimum Dimension |
Hearth slab thickness | 4" |
Hearth slab reinforcement | Reinforce sufficiently to carry its own weight plus any imposed weight |
Hearth side extensions (each side) | 8" for openings less than 6 square feet |
12" for openings for 6 square feet or more | |
Hearth front extension | 16" for openings less than 6 square feet |
20" for openings 6 square feet or more | |
Construction of firebox wall | 10" solid brick or 8" firebrick lining. All joints to be 1/4" maximum |
Distance from opening to throat | 8" |
Smoke chamber wall thickness | 6" |
Unlined walls | 8" |
Horizontal reinforcement of chimney | 1/4" ties at 18" on center and 2 ties at each bend in vertical steel |
Lintel | Shall be noncombustible material |
Chimney walls with flue lining | Solid masonry or hollow masonry (grouted solid) minimum 4" thick |
Chimney walls without flue lining | 8" solid masonry |
Distance between adjacent flues | A masonry with minimum of 4" and bonded into the walls of the chimney |
Flue area (based on area of fireplace opening) | See subsection I3 of this section |
Clearances: | |
Combustible materials | 2" |
Mantel and trim | Minimum of 6" from the opening. Combustible materials within a foot of the opening cannot project out more than 1/8" for each inch in distance of the opening |
Above roof | Minimum 3' at the roof line and 2' within 10' of the roof penetration |
Footings | See subsection 8-3-5H4 of this chapter |
(Ord. 2008-09-01, 9-24-2008)