The “R” values indicated below apply only to insulating materials, and as used in this section, the term “R” (Thermal Resistance) is the numerical reciprocal of thermal conductance (R=1/c). It is a measure of the resistance of a material to heat flow; the higher the “R” value, the better the insulating value. “R” values per inch of thickness will vary for different insulating materials. Therefore, a given “R” value may require a greater or lesser thickness of insulation.
Expressed in minimum “R” values, the minimum standards for insulating ceilings and walls shall be as follows:
Flat Roof Exterior Exterior Exterior Deck* Masonry Wall Frame Wall Doors Windows Construction Construction
________________________________________________________________________________ Ceiling Wall Ceiling Wall Stormed or Stormed or R-11 R-24 R-6 R-24 R-13 Insulated Type Insulated Glass |
*Construction where rigid roof insulation and exposed structural system is used. When a roof cavity is available, use standards listed for ceilings.
Minimum “R” values for floor areas over unheated basements, unheated crawl spaces or unheated garages:
Structural Slab Wood and Metal Framing R-7 R-11 |
A basement, crawl space or garage shall be considered to be unheated unless it is provided with a positive heat supply to maintain a minimum temperature of fifty degrees Fahrenheit.
Insulation of floors may be omitted over heated basement areas or where the basement sidewalls are insulated at R-6.
Foundation walls of basements need not be insulated except where habitable rooms are provided or where fifty percent (50%) or more of the wall section is above grade level.
Slab-on-grade floors shall be insulated down the exposed edge and under the slab twenty- four inches, or down the exposed edge of the slab and along the inside of the foundation for twenty-four inches. In such cases, the insulating material shall be of the rigid type with a minimum “R” value of five.
(Ord. 1998-8. Passed 6-1-98.)