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R.Townley Roofing |
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R. Townley Roofing wants to be your roofing contractor! |
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What is title 24??? |
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New 2008 Title-24 Cool Roof Requirements As of January 1, 2010, the California Energy Commission’s update Title-24 Building Energy Efficiency Standards for residential and non-residential roofing are now in force, otherwise known as “Cool-Roof”. The new Cool Roof requirements affect new construction, significant repairs of existing roofs, re-roofing, plus additions and alterations of existing buildings and homes. With the old 2005 Title-24 energy code a residential cool roof was an optional energy efficiency measure, however on January 1, 2010, Cool Roofs are now required for most residential buildings in many of California’s 16 climate zones. Cool Roof standards are designed to reduce air conditioner demands, save money, and reduce the urban heat island effect. Cool roof requirements for residential and non-residential now apply to low-slope and steep-slope roofs. The aged solar reflectance and thermal emittance requirements will vary, depending on the slope of the roof, climate zone, and the density of the roofing product. All roofing products must be certified and labeled according to the Cool Roof Rating Council (CRRC) to comply with the Standards. There are exceptions to both residential and non-residential requirements.
Here’s how it works: New Construction: First determine which climate zone your project is located in 1-16. The cool roof requirements vary depending on the climate zone. Next, determine your roof slope. The Title-24 prescriptive requirements divide roofs into two categories, Low Slope (less than 2:12 pitch) and Steep Slope (greater than 2:12pitch). Then determine the weight of the roofing material. The prescriptive tables divide roofing materials into two weight categories. Less than 5 lb/sq. ft. or greater than 5 lb/sq. ft. The Cool Roof requirements vary depending on roofing material weight. As a rule, lighter weight roofing material (asphalt shingles) have a lower cool roof requirements. Than heavier roofing products like tile roofing. Once you have these factors determined then you simply consult one of the most important tables in the new 2008 Title-24 Building Efficiency Standards, Table 151-D. This table outlines all of the residential prescriptive requirements, including the cool roof requirements. Table 151-D is divided into the 16 unique California Climate Zones with their own specific building component requirements per climate zone. First look across the top row to find your correct climate zone for your project location. We’ll use climate zone #8 for an example. Then go down along the left hand column until you come to “Roofing Products”. There you will select your roofing slope type and roofing weight per sq. ft. Then simply move to the right in the table until you see the Cool Roof requirements for your climate zone. In our example we are using tile roofing with a weight greater than 5 lb/ sq. ft. on a steep slope roof (greater than 2:12) and for climate zone #8 the cool roof requirements are and Aged Solar Reflectance of .015 and a Thermal Emittance of .075. That is your Cool Roof specification for your roofing product. In addition, whatever roofing product you select must meet these numbers and be certified by the Cool Roof Rating Council, (CRRC). There are cool roof products sold in California that are energy Star Certified but this does not automatically qualify the product as a CRRC certified product. |
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Re-Roofs Cool Roof requirements are triggered when either 50 percent of roof area or more than 1,000 sq. ft., whichever is less is replaced. The cool roof requirements for re-roofs are the same as for new construction and use the same values from Table 151-D noted above. However there are exceptions which can be used to offset the cool roof requirement. If one of the exceptions below applies then the cool roof requirements are not triggered: Exceptions: 1. Buildings with no ducts in the attic, or 2. A radiant barrier is installed in the attic meeting the radiant barrier requirements of section 52(f) 2 of Title-24 Standards, or 3. Buildings with at least R-30 ceiling insulation or, 4. Buildings in Climate Zones 10, 11,13 and 14, R-3 or greater roof deck insulation above a vented attic, or 5. Existing ducts in the attic are insulated a sealed and HERS tested according to section151(f) 0, or 6. Insulation with a thermal resistance of at least 0.85hr ft2 degree F/btu or at least 3/4 inch air-space is added to the roof deck over an attic, or 7. In climate zones, 10, 12, and 13, with 1 sq. ft. free ventilation area of attic ventilation area is within two feet vertical distance of the roof ridge: or 8. If the building can show compliance without cool roof using the performance approach (Title-24 calculation). |