Business and Professions Code section 19020

“R-value” means a measure of thermal resistance of material or composite materials. “R-value” is equal to the reciprocal of the conductance of a given material, or

R-value =

conductance of the material

where the conductance of the material is: Btu (hour × square foot × Fahrenheit degree average temperature difference between two surfaces).

Source: Section 19020, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=BPC§ionNum=19020. (updated Jan. 1, 1984; accessed Jun. 25, 2025).

Up to date

Verified:
Jun. 25, 2025

§ 19020's source at ca.gov

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Location: https://california.public.law/codes/business_and_professions_code_section_19020

Original Source: Section 19020, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=BPC§ionNum=19020. (last accessed May 12, 2025).