Construction Guidelines for Tiny Homes

Purpose

The following is a summary of codes and regulation with respect to the construction of "tiny homes". This handout may not be all inclusive, and it is recommended that you refer to the currently adopted Rutherford County Zoning Ordinance and 2018 International Residential Code (IRC) - Appendix Q-Tiny Houses. For specific questions, we encourage you to contact our office at (615) 898-7734.

What is a "Tiny House"?

A "tiny house", as defined by Section AQ102.1 of the 2018 International Residential Code, is a dwelling "400 square feet or less in floor area excluding lofts". Tiny houses regulated by the International Residential Code and NOT fabricated in a different location and relocated to a lot within Rutherford County. 

A Manufactured "Tiny House" is any dwelling built off-site and regulated under the Tennessee Modular Buildings Act. This program is under authority of T.C.A. 68-126-301. The program includes housing that is produced in factories and transported to building sites to be installed. The manufacturers of such 'tiny' modular homes are/shall be licensed by the State of Tennessee, regulated under the supervision of the state program, and are required to have a permanently affixed Tennessee Modular Building label. The label is required to be attached by means of four (4) pop rivets or drive screws on a permanent, non-removable building component as evidence of compliance of the program. The regulation of manufactured "mobile homes" is the responsibility of the U.S. Department of Housing and Urban Development (HUD).

Permitting and Inspections

Any new Tiny House construction requires submittal of a permit application package which includes the following:

• Completed application form
• Zoning compliance form completed by the Planning and Engineering Department 
• An architectural floor plan of the proposed structure
• Construction drawings
• A site plan (dimensioned to lot lines and all other structures on the same lot)
• A septic permit for a new system or evidence of an existing system that the unit will connect to

Upon approval, applicable building and subtrade permits can be issued, at which time, work may begin. Structures shall be inspected by the Rutherford County Building Codes Department, throughout the construction process, as defined in an inspection checklist that will be provided at permit issuance. No structure is permitted to be occupied prior to a final inspection and issuance of a Certificate of Occupancy. 

Construction Requirements

• General
  • Tiny homes must meet ALL requirements of Rutherford County Planning and Engineering Department where it applies to setbacks, lot sizes, site requirements.
  • Tiny homes shall be constructed upon a permanent foundation compliant with 2018 IRC, Chapter 4 - Foundations
  • Electrical systems shall be permitted and inspected by the Tennessee State Fire Marshal's Office
• Habitable Space
  • Habitable Space is defined as a space in a building for living, sleeping, eating or cooking. Bathrooms, toilet rooms, closets, halls, storage, or utility spaces and similar areas are not considered habitable space and do not contribute to minimum habitable space required. 
  • Habitable rooms shall not have less than 70 square feet of floor area (except for kitchens) with not less than 7' in any horizontal dimension (R304.0)
  • Portions of sloped ceiling measuring less than 5' will not be permitted to contribute the minimum required habitable area for that room (R305.1)
• Emergency Escape and Rescue Openings
  • Tiny Homes shall meet the requirements of 2018 IRC, Section R310 for emergency escape and rescue openings
  • Exception: Egress roof access windows in lofts used as sleeping rooms shall be deemed to meet the requirements of r130 where installed such that the bottom of the opening is not more than 44" above loft floor, provided the egress roof access window complies with minimum opening area requirements of R310.2.1 (AQ105.1)
• Sanitation
  • Tiny homes shall be provided with permanent provisions for living, sleeping, eating, cooking, and sanitation (R202)
  • Tiny homes shall be provided with connection to an APPROVED method of sewage disposal and an APPROVED water supply providing hot and cold water (R306.3/306.4)
  • Units shall be provided with a separate bathroom containing a water closet, lavatory, and bathtub or shower (R306.1)
  • Each tiny house shall be provided with a kitchen area with a sink (R306.2)
• Light, Ventilation, and Heating
  • Habitable rooms shall be provided with light and ventilation via operable glazing not less than 8% of floor area (R303.1)
  • Bathrooms shall be provided with operable window(s) of not less than 3 square feet or provided with local exhaust (R303.3)
  • Tiny homes shall provide a heating facility capable of maintaining a minimum 68 degrees fahrenheit (R303.10)
• Energy Conservation
  • Tiny homes shall meet all building thermal envelope, mechanical ventilation, and systems requirements of the 2018 IRC Chapter 11 - with adopted amendments
• Lofts/Stairways
  • Minimum area: Lofts shall have a floor area of not less than 35 square feet (AQ104.1.1)
  • Minimum dimensions: Lofts shall be not less than 5 feet in any horizontal dimension (AQ104.1.2) 
  • Height effect on loft area: Portions of a loft with a sloped ceiling measuring less than 3 feet from the finished floor to the finished ceiling shall not be considered as contributing to the minimum required area for the left. (AQ104.1.3)
  • Height effect on loft area - Gable Roofs: Under gable roofs with a minimum slope of 6 units vertical in 12 units horizontal (50-percent slope), portions of a loft with a sloped ceiling measuring less than 16 inches from the finished floor to the finished ceiling shall not be considered as contributing to the minimum required area for the loft (AQ104.1.3)
  • Loft Access
    • Stairways
      • Width: Stairways accessing a loft shall not be less than 17 inches in clear width at or above the handrail. The width below the handrail shall be not less than 20 inches. (AQ104.2.1.1)
      • Headroom: The headroom in stairways accessing a loft shall be not less than 6 feet 2 inches, as measured vertically, from a sloped line connecting the tread or landing platform nosings in the middle of their width. (AQ104.2.1.2)
      • Treads and risers: Risers for stairs accessing a loft shall be not less than 7 inches and not more than 12 inches in height. Tread depth and riser height shall be calculated in accordance with one of the following formulas: 1. The tread depth shall be 20 inches minus three-fourths of the tread depth. (AQ104.2.1.3)
      • Landing platforms: The top tread and riser of stairways accessing lofts shall be constructed as a landing platform, where the loft ceiling height is less than 6 feet, 2 inches where the stairway meets the loft. The landing platform shall be 18 inches to 22 inches in depth measured from the nosing of the landing platform to the edge of the loft, and 16 to 18 inches in height measured from the landing platform to the loft floor. (AQ104.2.1.4)
      • Handrails: Handrails shall comply with Section R311.7.8. (AQ104.2.1.5)
      • Stairway guards: Guards at open sides of stairways shall comply with Section R312.1. (AQ104.2.1.6)
    • Ladders
      • Ladders: Ladders accessing lofts shall comply with Sections AQ104.2.1 and AQ104.2.2. (AQ104.2.2)
      • Size and capacity: Ladders accessing lofts shall have a rung width of not less than 12 inches, and 10-inch to 14-inch spacing between rungs. Ladders shall be capable of supporting a 200-pound load on any rung. Rung spacing shall be uniform within 3/8 inch. (AQ104.2.2.1)
      • Incline: Ladders shall be installed at 70 to 80 degrees from horizontal (AQ104.2.2.2)
    • Alternating Tread Devices
      • Alternating tread devices accessing lofts shall comply with Sections R311.7.11.1 and R311.7.11.2. The clear width at and below the handrails shall be not less than 20 inches. (AQ104.2.3)
    • Ships ladders
      • Ships ladders accessing lofts shall comply with Sections R311.7.12.1 and R311.7.12.2. The clear width at and below handrails shall be not less than 20 inches. (AQ104.2.4)
    • Loft Guards
      • Loft guards shall be located along the open side of lofts. Loft guards shall be not less than 36 inches in height or one-half of the clear height to the ceiling, whichever is less. (AQ104.2.5)