CA Title 24
Modified: 11/01/2013
Green Guide
California's Title 24 is the Energy Building Regulation that applies to every new building and runs parallel with California's building code for safety. This regulation defines how a building is to be designed to save energy using the latest technologies for maximized savings. In October of 2005, the new 2005 Title 24 went into practice. It contains specific requirements for low-sloped roofing systems.

Building Categories

2004 Title 24 covers building categories
  • New construction
  • Major renovations
  • Additions
  • Alterations
  • Repairs

Qualifications for Cool Roofs

  • Designates Cool Roof Rating Council (CRRC) as the Supervisory Entity
  • Requires CRRC testing and labeling starting January 1, 2003 for compliance
  • Tested and labeled to CRRC- 1 – 2002
  • Initial thermal emittance (ε) > 0.75
  • Initial solar reflectance (P) > 0.70
  • Liquid coatings shall meet the same requirements for reflectivity and emittance and be applied at specific minimum thickness:
    • General coatings – 20 mils dry (2.5 gal/100 sqft @ 50% solids)
    • Cement – based coatings:
      • 30 mils dry over capsheet
      • 40 mils dry over metal
      • 200 mils dry over rock or gravel
      • 20% minimum cement content
    • Aluminum-pigmented asphalt shall meet
      • ASTM D2824
      • ASTM D3805

New Low-Slope Standards

2005 Non-residential standard new low-slope roofs:

Prescriptive Approach

  • Envelope component approach – “Check-Off List” where the actual component is “checked-off” against the Title 24 requirements as meeting or exceeded it
    • Cool Roof required
  • Overall envelope approach – Heat Gain trade-off calculation method must be used:
    • Standard Building envelope heat gain calculation is based on code – Cool Roof values used in the calculation
    • Proposed Building – Overall heat gain tradeoffs between the envelope components to achieve an energy value < the Standard Building value

Performance Approach – Whole building Energy Calculation method must be used (computer model required):

  • Standard Building energy load is based on code – Cool Roof used in the calculation
  • The Proposed Building energy load is developed using tradeoffs between the various building components to achieve an energy value < the Standard Building value

If roof product is not listed with CRRC, the reflective value used in the calculations for Envelope and Performance Aapproaches is P = 0.10

New Low-Slope Replacement Roof Standards

2005 Non-residential standard replacement low-slope roofs:

  • Replacement, recovering, recoating – Cool Roof required
  • Title 24 applies when more than 50% of roof is replaced or more than 2,000 sqft is replaced, whichever is less
  • Very limited exemption for recovering of build-up roofs with rock or gravel surfaces.
    • Cool roof is not required when all of the following occur:
      • Existing roof is rock or gravel surface (mineral surface roofs not included!)
      • New roof is rock or gravel surface
      • No removal of existing layers of roof coverings
      • No recoating with a liquid applied coating
      • No installation of recover board, rigid insulation or other rigid substrate. Between the existing and new roof
  • Performance standards alternative (Overall Envelope Approach or Performance Approach) – of little benefit in reroofing

2005 Non-residential standards insulation

  • Insulation shall be in direct contact with a continuous roof or ceiling
  • Maybe installed above or below the roof deck or on a drywall ceiling
  • Insulation placed on top of a suspended ceiling shall be deemed to have no affect on heat loss
  • Standing Seam Metal Roofs, roofs with metal decks, and wood decks with metal supports – the R-value must be made up by either
    • Continuous rigid insulation meeting the full R-value required is stalled either above the roof deck or between the roof deck and the structural members supporting the roof deck, or
    • Continuous rigid insulation of R-10 installed either above the roof deck or between the roof deck and the structural members supporting the roof and insulation > than the required R-value installed between the structural members, or
    • Continuous bat insulation > the required R-value installed between the roof deck and the structural supports and in addition must have thermal blocks of R-5 installed between the purlins and the deck

2005 Standards Implementation

  • Effective October 1, 2005
  • Compliance Manuals to further explain standards will be issued
  • Training is available from the California Energy Commission, Utilities and Versico

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