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 Carlisle