Metro Government of Nashville and Davidson County

§ 16.08.014. Amendments to the International Residential Code for One- and Two-Family Dwellings.

Latest version.

The following amendments, deletions, or additions to the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings are adopted by reference, as fully as though copied into such Dwelling Code, and thereby made a part of the Dwelling Code.

Section R101.1 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Section R101.1 and substituting the following:

R101.1 Title. These provisions shall be known as the Residential Code for One- and Two-family Dwellings of Metro Nashville, Tennessee, and shall be cited as such and will be referred to herein as "this code".

Sections R103.1 through R105.9 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Sections R103.1 through 105.9 in their entirety.

Section R106.1.3 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Section R106.3.1 in its entirety.

Section R107.1 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting R107.1 Section and substituting the following: R107.1 General. The building official is authorized to issue a permit for temporary structures and temporary uses. Such permits shall be limited as to time of service, but shall not be permitted for more than 90 days. The building official is authorized to grant extensions for demonstrated cause.

Sections R108.1 through R108.6 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Sections R108.1 through 108.6 in their entirety.

Section R109.1.3 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Section R109.1.3 in its entirety.

Section R202 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by adding the following new definitions to Section R202.

BED AND BREAKFAST HOMESTAY—means a private home, inn or other unique residential facility located in a structure of historical significance as defined in Tennessee Code Annotated Section 68-14-503(3) offering bed and breakfast accommodations and one (1) daily meal and having less than four (4) guest rooms furnished for pay, with guest staying not more than fourteen (14) days, and where the innkeeper resides on the premises or property, or immediately adjacent to it. Guest rooms shall be established and maintained distinct and separate from the innkeeper's quarters.

BOARD—shall mean the Metropolitan Board of Fire and Building Code Appeals.

DIRECTOR—shall mean the Director of the Metropolitan Department of Codes Administration, his deputy or duly authorized representative.

NORMAL MAINTENANCE REPAIRS—shall be defined as repairs to an existing building or structure, including but not limited to exterior and interior painting, papering, glazing of windows and doors, floor finishing, minor repairs to chimneys, stairs, porches, underpinning, and repairs to an existing roof.

TEMPORARY—shall mean not more than 90 calendar days.

Section R202 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting the definitions of "Building Official," and substituting the following:

BUILDING OFFICIAL—shall mean the Director of the Metropolitan Department of Codes Administration.

Table R301.2(1) of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Table R301.2(1) and substituting the following:

Table R301.2(1) CLIMATIC AND GEOGRAPHIC DESIGN CRITERIA

Ground Snow Load = 10#

Wind Speed MPH = 90

Seismic Design = C

Subject to Damage From:

Weathering = Severe

Frost Depth = 12"

Termite = Heavy

Decay = Severe

Winter Design Temperature = 14 °F

J. Section R306 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by adding Section R306.5:

R306.5 Clothes Washing facilities. Every dwelling unit shall be provided with a washing machine connection, a dryer electrical connection and a vent for the dryer.

Section R309.3 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Section R309.3 in its entirety.

R309.5 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Section R309.5 in its entirety.

R313.1 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by creating a new Section R313.1.

R313.1 Townhouse automatic fire sprinkler systems. A townhouse shall be considered a separate building with independent exterior walls and shall be separated by a two-hour fire-resistance-rated wall assembly. A townhouse shall be built according to local and statewide adopted building codes; provided, however, a fire sprinkler system shall not be required for a townhouse. For the purposes of this Code, "townhouse" means a single family dwelling unit constructed in a group of three (3) or more attached units that extends from foundation to roof, not more than three (3) stories in height, with a separate means of egress, and an open space or public way on at least two (2) sides.

R313.2 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Section R313.2 in its entirety.

Section R319 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Section R319 and substituting the following:

R319. Premises Identification. All buildings and structures within Metropolitan Nashville and Davidson County shall have approved address numbers posted in accordance with following: Residences are to have their numbers at least three (3) inches in size, on a contrasting background, and in a position to be plainly visible and legible from the street or road fronting the property. The numbers may be attached to the residence or the mailbox, if the mailbox is next to the street.

Sections R322.1 through R322.3.6 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Sections R322.1 through 322.3.6 in their entirety.

Chapter 3 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by adding the following new section R324:

SECTION R324—HOUSE MOVING

Any person desiring to move any house, building, or structure shall comply with all of the provisions set forth in Section 16.28.175 of the Metropolitan Code and other provisions of this Code.

Section R403.1 of the 2012 Edition of the International Residential Code for One- and two-Family Dwellings is hereby amended by deleting Section R403.1 and substituting the following:

R403.1 General. All exterior walls shall be supported on continuous solid or fully grouted masonry or concrete footings, wood foundations, or other approved structural systems which shall be of sufficient design to accommodate all loads according to Section R301 and to transmit the resulting loads to the soil within the limitations as determined from the character of the soil. Footings shall be supported on undisturbed natural soils or engineered fill. All concrete footing shall have minimum bottom reinforcement. Minimum reinforcement shall be 2-#4's continuous and shall be located a minimum of 3 inches clear from the bottom and side of the footing.

Section R501.3 of the 2012 Edition of the International Residential Code for One- and two-Family Dwellings is hereby amended by deleting Section R501.3 and substituting the following:

R501.3 Fire protection of floors. Floor assemblies, not required elsewhere in this code to be fire-resistance rated, shall be provided with a 1/2-inch (12.7 mm) gypsum wallboard membrane, 5/8-inch (16 mm) wood structural panel membrane, or equivalent on the underside of the floor framing member.

Exceptions:

Floor assemblies located directly over a space protected by an automatic sprinkler system in accordance with Section P2904, NFPA13D, or other approved equivalent sprinkler system.

Floor assemblies located directly over a crawl space not intended for storage.

Portions of floor assemblies can be unprotected when complying with the following:

3.1.

The aggregate area of the unprotected portions shall not exceed 80 square feet per story

3.2.

Fire blocking in accordance with Section R302.11.1 shall be installed along the perimeter of the unprotected portion to separate the unprotected portion from the remainder of the floor assembly.

Wood floor assemblies using dimension lumber or structural composite lumber equal to or greater than 2-inch by 10-inch (50.8 mm by 254 mm) nominal dimension, or other approved floor assemblies demonstrating equivalent fire performance.

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Table N1102.1.1(R402.1.1) 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Table N1102.1.1(R402.1.1) and substituting a new Table N1102.1.1(R402.1.1):

Climate Zone	Fenestration U-Factor ^b	Skylight ^b U-Factor	Glazed Fenestration SHGC ^b,e	Ceiling R-Value	Wood Frame Wall R-Value	Mass Wall R-Value ⁱ	Floor R-Value	Basement ^c Wall R-Value	Slab ^d R-Value & Depth	Crawl Space ^c Wall R-Value
1	NR	0.75	0.25	30	13	3/4	13	0	0	0
2	0.40	0.65	0.25	38	13	4/6	13	0	0	0
3	0.35	0.55	0.25	38	20 or 13 + 5 ^h	8/13	19	5/13 ^f	0	5/13
4 except Marine	0.35	0.60	NR	38	13	5/10	19	10/13	10, 2 ft	10/13
5 and Marine 4	0.32	0.55	NR	49	20 or 13 + 5 ^h	13/17	30 ^g	15/19	10, 2 ft	15/19
6	0.32	0.55	NR	49	20 + 5 or 13 10 ^h	15/20	30 ^g	15/19	10, 4 ft	15/19
7 and 8	0.32	0.55	NR	49	20 + 5 or 13 10 ^h	19/21	38 ^g	15/19	10, 4 ft	15/19

Foot notes:

For SI: 1 foot = 304.8 mm.

a. R-values are minimums. U-factors and SHGC are maximums. When insulation is installed in a cavity which is less than label or design thickness of the insulation, the installed R-value of the insulation shall not be less than the R-value specified in the table.

b. ;hg;The fenestration U-factor column excludes skylights. The SHGC column applies to all glazed fenestration.

Exception: Skylights may be excluded from glazed fenestration SHGC requirements in Climate Zones 1 through 3 where the SHGC for such skylights does not exceed 0.30.

c. "15/19" means R-15 continuous insulation on the interior or exterior of the home or R-19 cavity insulation at the interior the basement wall. "15/19" shall be permitted to be met with R-13 cavity insulation on the interior of the basement wall plus R-5 continuous insulation on the interior or exterior of the home. "10/13" means R-10 continuous insulation on the interior or exterior of the home or R-13 cavity insulation at the interior of the basement wall.

d. R-5 shall be added to the required slab edge R-values for heated slabs. Insulation depth shall be the depth of the footing or 2 feet, whichever is less in Zones 1 through 3 for heated slabs.

e. There are no SHGC requirements in the Marine Zone.

f. Basement wall insulation is not required in warm-humid locations as defined by Figure N1101.10 and Table N1101.10.

g. Or insulation sufficient to fill the framing cavity, R-19 minimum.

h. First value is cavity insulation, second is continuous insulation or insulated siding, so "13 + 5" means R-13 cavity insulation plus R-5 continuous insulation or insulated siding. If structural sheathing covers 40 percent or less of the exterior, continuous insulation R-value shall be permitted to be reduced by no more than R-3 in the locations where structural sheathing is used - to maintain a consistent total sheathing thickness.

i. The second R-value applies when more than half the insulation is on the interior of the mass wall.

Table N1102.1.3(R402.1.3) of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Table N1102.1.3(R402.1.3) and substituting a new Table N1102.1.3(R402.1.3):

TABLE N1102.1.3 (R402.1.3)
EQUIVALENT U-FACTORS

Climate Zone	Fenestration U-Factor	Skylight U-Factor	Ceiling U-Factor	Frame Wall U-Factor	Mass Wall U-Factor ^b	Floor U-Factor	Basement Wall U-Factor	Crawl Space Wall U-Factor
1	0.50	0.75	0.035	0.082	0.197	0.064	0.360	0.477
2	0.40	0.65	0.030	0.082	0.165	0.064	0.360	0.477
3	0.35	0.55	0.030	0.057	0.098	0.047	0.091 ^c	0.136
4 except Marine	0.35	0.60	0.030	0.082	0.141	0.047	0.059	0.065
5 and Marine 4	0.32	0.55	0.026	0.057	0.082	0.033	0.050	0.055
6	0.32	0.55	0.026	0.048	0.060	0.033	0.050	0.055
7 and 8	0.32	0.55	0.026	0.048	0.057	0.028	0.050	0.055

a. Nonfenestration U-factors shall be obtained from measurement, calculation or an approved source.

b. When more than half the insulation is on the interior, the mass wall U-factors shall be a maximum of 0.17 in Zone 1, 0.14 in Zone 2, 0.12 in Zone 3, 0.087 in Zone 4 except Marine, 0.065 in Zone 5 and Marine 4, and 0.057 in Zone 6 through 8.

c. Basement wall U-factor of 0.360 in warm-humid locations as defined by Figure 301.1 and Table 301.1.

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Section N1102.4.1.2 of the 2012 Edition of the International Residential Code for One- and two-Family Dwellings is hereby amended by deleting Section N1102.4.1.2 and substituting the following:

N1102.4.1.2 (R402.4.1.2) Testing. A newly constructed building or dwelling unit shall be tested and verified as having an air leakage rate of not exceeding 7 air changes per hour. Testing shall be conducted with a blower door at a pressure of 0.2 inches w.g. (50 Pascals). Where required by the building official, testing shall be conducted by an approved third party. A written report of the results of the test shall be signed by the party conducting the test and provided to the building official. Testing shall be performed at any time after creation of all penetrations of the building thermal envelope. During testing:

Exterior windows and doors, fireplace and stove doors shall be closed, but not sealed, beyond the intended weatherstripping or other infiltration control measures;

Dampers including exhaust, intake, makeup air, backdraft and flue dampers shall be closed, but not sealed beyond intended infiltration control measures;

Interior doors, if installed at the time of the test, shall be open;

Exterior doors for continuous ventilation systems and heat recovery ventilators shall be closed and sealed;

Heating and cooling systems, if installed at the time of the test, shall be turned off; and

Supply and return registers, if installed at the time of the test, shall be fully open.

The test must be performed by a person certified as a Home Energy Rating Systems (HERS) rater or Duct and Envelope Tightness Verifier or who possesses a current professional certification from HERS rater, Building Performance Institute or other similar entity. The test cannot be performed by the prime contractor as listed on the building permit or a direct employee of the prime contractor. A certification from the person performing the test shall be with the following information:

Address where test was performed.

Name of person performing test.

Company name.

Date test was performed; and

Results of test in A.C.H.

Beginning at the time of adoption of this Code, all testing will be required, all documents shall be provided and attached to the dwelling appropriately. There is a grace period for airtightness compliance until January 1, 2016.

Section N1103.2.2 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Section N1103.2.2 and substituting the following:

N1103.2.2 (R403.2.2) Sealing (Mandatory). Ducts, air handlers, and filter boxes shall be sealed. Joints and seams shall comply with Section M1601.4.1 of this code.

Exceptions:

Air-impermeable spray foam products shall be permitted to be applied without additional joint seals.

Where a duct connection is made that is partially inaccessible, three screws or rivets shall be equally spaced on the exposed portion of the joint so as to prevent a hinge effect.

Continuously welded and locking-type longitudinal joints and seams in ducts operating at static pressures less than 2 inches of water column (500 Pa) pressure classification shall not require additional closure systems.

Duct tightness shall be verified by either of the following:

Postconstruction test: Total leakage shall be less than or equal to 12 cfm (113.3 L/min) per 100 square feet (9.29 m2) of conditioned floor area when tested at a pressure differential of 0.1 inches w.g. (25 Pa) across the entire system, including the manufacturer's air handler enclosure. All register boots shall be taped or otherwise sealed during the test.

Rough-in test: Total leakage shall be less than or equal to 12 cfm (113.3 L/min) per 100 ft2 (9.29 m2) of conditioned floor area when tested at a pressure differential of 0.1 inches w.g. (25 Pa) across the system, including the manufacturer's air handler enclosure. All registers shall be taped or otherwise sealed during the test. If the air handler is not installed at the time of the test, total leakage shall be less than or equal to 12 cfm (85 L/min) per 100 square feet (9.29 m2) of conditioned floor area.

Exception: The total leakage test is not required for ducts and air handlers located entirely within the building thermal envelope.

Section N1104 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Section N1104 in its entirety.

Standard Reference Design for the Air Exchange Rate, Table N1105.5.2(1), of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Standard Reference Design for the Air Exchange Rate, Table N1105.5.2(1) and substituting the following:

Air leakage rate of 5 air changes per hour. in Zones 1 and 2, and 7 air changes per hour in Zones 3 through 8 at a pressure of 0.2 inches w.g (50 Pa). The mechanical ventilation rate shall be in addition to the air leakage rate and the same as in the proposed design, but no greater than 0.01 × CFA + 7.5 × (N ^br + 1) where: CFA = conditioned floor area N ^br = number of bedrooms Energy recovery shall not be assumed for mechanical ventilation.

Sections M1201.1 through E4304.5 of the 2012 Edition of the International Residential Code for One- and Two-Family Dwellings is hereby amended by deleting Sections M1201.1 through E4304.5 in their entirety.

(Ord. BL2015-1145 § 8, 2015; Ord. BL2010-613 § 1, 2010; Ord. BL2007-1373 § 2, 2007; Ord. BL2001-703 § 2, 2001; Ord. 98-1445 §§ 45—47, 1998; Ord. 96-562 §§ 9—25, 1996; Ord. 95-1542 § 3, 1995; Ord. 95-1487 §§ 20—27, 1995; Ord. 92-118 § 4, 1992)

                    
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