(a)  Insulation Certification by Manufacturers.

Any insulation shall be certified by Department of Consumer Affairs, Bureau of Home Furnishing and Thermal Insulation that the insulation conductive thermal performance is approved pursuant to the California Code of Regulations, Title 24, Part 12, Chapters 12-13, Article 3, “Standards for Insulating Material.”

(b) Installation of Urea Formaldehyde Foam Insulation.

Urea formaldehyde foam insulation may be applied or installed only if:

1.   It is installed in exterior side walls; and

2.   A four-mil-thick plastic polyethylene vapor retarder or equivalent plastic sheathing vapor retarder is installed between the urea formaldehyde foam insulation and the interior space in all applications.

(c)  Flame Spread Rating of Insulation.

All insulating material shall be installed in compliance with the flame spread rating and smoke density requirements of the CBC.

(d) Installation of Insulation in Existing Buildings.

Insulation installed in an existing attic, or on an existing duct or water heater, shall comply with the applicable requirements of Subsections 1, 2, and 3 below. If a contractor installs the insulation, the contractor shall certify to the customer, in writing, that the insulation meets the applicable requirements of Subsections 1, 2, and 3 below.

1.   Attics. If insulation is installed in the existing attic of a low-rise residential building, the R-value of the total amount of insulation (after addition of insulation to the amount, if any, already in the attic) shall meet the requirements of Section 150.0(a).

EXCEPTION to Section 110.8(d)1: Where the accessible space in the attic is not large enough to accommodate the required R-value, the entire accessible space shall be filled with insulation provided such installation does not violate Section 1203.2 of Title 24, Part 2.

2.   Water heaters. If external insulation is installed on an existing unfired water storage tank or on an existing back-up tank for a solar water-heating system, it shall have an R-value of at least R-12, or the heat loss of the tank surface based on an 80°F water-air temperature difference shall be less than 6.5 Btu per hour per square foot.

3.   Ducts. If insulation is installed on an existing space-conditioning duct, it shall comply with Section 605.0 of the CMC.

(e)  Insulation Placement on Roof/Ceilings.

Insulation installed to limit heat loss and gain through the top of conditioned spaces shall comply with the following:

1.   Insulation shall be installed in direct contact with a continuous roof or ceiling which is sealed to limit infiltration and exfiltration as specified in Section 110.7, including but not limited to placing insulation either above or below the roof deck or on top of a drywall ceiling; and

2.   When insulation is installed at the roof in nonresidential buildings, fixed vents or openings to the outdoors or to unconditioned spaces shall not be installed and the space between the ceiling and the roof is either directly or indirectly conditioned space and shall not be considered an attic for the purposes of complying with CBC attic ventilation requirements; and

3.   Insulation shall not be placed on top of a suspended ceiling with removable ceiling panels to meet the Roof/Ceiling requirement of Sections 120.7, 140.3 and  141.0; and

EXCEPTION to Section 110.8(e)3: When there are conditioned spaces with a combined floor area no greater than 2,000 square feet in an otherwise unconditioned building, and when the average height of the space between the ceiling and the roof over these spaces is greater than 12 feet, insulation placed in direct contact with a suspended ceiling with removable ceiling panels shall be an acceptable method of reducing heat loss from a conditioned space and shall be accounted for in heat loss calculations.

4.   Insulation shall be installed below the roofing membrane or layer used to seal the roof from water penetration unless the insulation has a maximum water absorption of 0.3 percent by volume when tested according to ASTM Standard C272.

NOTE: Vents, that do not penetrate the roof deck, that are designed for wind resistance for roof membranes are not within the scope of Section 110.8(e)2.

(f)  Insulation for Demising Walls in Nonresidential Buildings.

The opaque portions of framed demising walls in nonresidential buildings shall be insulated with an installed R-value of no less than R-13 between framing members.

(g) Insulation Requirements for Heated Slab Floors.

Heated slab floors shall be insulated according to the requirements in Table 110.8-A.

1.   Insulation materials in ground contact must:

A.   Comply with the certification requirements of Section 110.8(a); and

B.   Have a water absorption rate for the insulation material alone without facings that are no greater than 0.3 percent when tested in accordance with Test Method A – 24 Hour-Immersion of ASTM C272.

C.   Water vapor permeance no greater than 2.0 perm/inch when tested in accordance with ASTM E96.

2.   Insulation installation must:

A.   Be covered with a solid guard that protects against damage from ultraviolet radiation, moisture, landscaping operation, equipment maintenance, and wind; and

B.   Include a rigid plate, which penetrates the slab and blocks the insulation from acting as a conduit for insects from the ground to the structure above the foundation.


Insulation Location

Insulation Orientation

Installation Requirements

Climate Zone




Outside edge of heated slab, either inside or outside the foundation wall


From the level of the top of the slab, down 16 inches or to the frost line, whichever is greater. Insulation may stop at the top of the footing where this is less than the required depth. For below grade slabs, vertical insulation shall be extended from the top of the foundation wall to the bottom of the foundation (or the top of the footing) or to the frost line, whichever is greater.

1 – 15




Between heated slab and outside foundation wall

Vertical and Horizontal

Vertical insulation from top of slab at inside edge of outside wall down to the top of the horizontal insulation. Horizontal insulation from the outside edge of the vertical insulation extending 4 feet toward the center of the slab in a direction normal to the outside of the building in plan view.

1 – 15



10 vertical and 7 horizontal


(h) Wet Insulation Systems.

When insulation is installed on roofs above the roofing membrane or layer used to seal the roof from water penetration, the effective R-value of the insulation shall be as specified in Reference Joint Appendix JA4.

(i)   Roofing Products Solar Reflectance and Thermal Emittance.

1.   In order to meet the requirements of Sections 140.1, 140.2, 140.3(a)1, 141.0(b)2B, 150.1(c)11,  150.2(b)1H or 150.2(b)2 a roofing product’s thermal emittance and an aged solar reflectance shall be certified and labeled according to the requirements of Section 10-113.

EXCEPTION 1 to Section 110.8(i)1:  Roofing products that are not certified according to Section 10-113 shall assume the following default aged solar reflectance/thermal emittance values:

A.   For asphalt shingles: 0.08/0.75

B.   For all other roofing products: 0.10/0.75

2.   If CRRC testing for an aged solar reflectance is not available for any roofing products, the aged value shall be derived from the CRRC initial value using the equation ρaged=[0.2+β[ρinitial-0.2], where ρinitial = the initial solar reflectance and soiling resistance β is listed by product type in TABLE 110.8-B.


Product Type

CRRC Product Category


Field-Applied Coating

Field-Applied Coating




Not A Field-Applied Coating



3.   Solar Reflectance Index (SRI), calculated as specified by ASTM E 1980-01, may be used as an alternative to thermal emittance and an aged solar reflectance when complying with the requirements of Sections 140.1, 140.2, 140.3(a)1, 141.0(b)2B, 150.1(c)11, 150.2(b)1H,or 150.2(b)2. SRI calculations shall be based on moderate wind velocity of 2-6 meters per second. The SRI shall be calculated based on the aged reflectance value of the roofing products.

4.   Liquid applied roof coatings applied to low-sloped roofs in the field as the top surface of a roof covering shall:

A.   Be applied across the entire roof surface to meet the dry mil thickness or coverage recommended by the coating manufacturer, taking into consideration the substrate on which the coating is applied, and

B.   Meet the minimum performance requirements listed in TABLE 110.8-C or the minimum performance requirements of ASTM C836, D3468, D6083, or D6694, whichever are appropriate to the coating material.

EXCEPTION 1 to Section 110.8(i)4B: Aluminum-pigmented asphalt roof coatings shall meet the requirements of ASTM D2824 or ASTM D6848 and be installed as specified by ASTM D3805.

EXCEPTION 2 to Section 110.8(i)4B: Cement-based roof coatings shall contain a minimum of 20 percent cement and shall meet the requirements of ASTM C1583, ASTM D822, and ASTM D5870.



Physical Property

ASTM Test Procedure


Initial percent elongation (break)

D 2370

Minimum 200% 73° F (23° C)

Initial percent elongation (break)


Initial Flexibility

D 2370


D522, Test B

Minimum 60% 0° F (-18° C)


Minimum pass 1” mandrel 0° F (-18° C)

Initial tensile strength (maximum stress)

D 2370

Minimum 100 psi (1.38 Mpa) 73° F (23° C)

Initial tensile strength (maximum stress)


Initial Flexibility

D 2370


D522, Test B

Minimum 200 psi (2.76 Mpa) 0° F (-18° C)


Minimum pass 1” mandrel 0° F (-18° C)

Final percent elongation (break) after accelerated weathering 1000 h


Minimum 100% 73° F (23° C)

Final percent elongation (break) after accelerated weathering 1000 h


Flexibility after accelerated weathering 1000h


Minimum 40% 0° F (-18° C)


Minimum pass 1” mandrel 0° F (-18° C)


D 1653

Maximum 50 perms

Accelerated weathering 1000 h

D 4798

No cracking or checking1

1. Any cracking or checking visible to the eye fails the test procedure.


j) Radiant Barrier.

A radiant barrier shall have an emittance of 0.05 or less, tested in accordance with ASTM C1371 or ASTM E408, and shall be certified to the Department of Consumer Affairs as required by Title 24, Part12, Chapter 12-13, Standards for Insulating Material.