Cedar Shakes & Shingles
The Cedar Shake & Shingle Bureau is very involved in building code work. Certi-label™ cedar products are manufactured to CSSB-97 grading rules, which have been adopted by the U.S. International Building Code (IBC) and the U.S. International Residential Code (IRC) and the National Building Code (NBC). Certi-label™ shakes and shingles meet all national standards for shakes and shingles. The following code bodies and manufacturing standards in the United States and Canada govern shake and shingle manufacturing and application:
· American Society for Testing and Material (ASTM)
· California State Fire Marshall (CSFM)
· Canadian Standards Association (CSA)
· Cedar Shake and Shingle Bureau
· International Accreditation Service (IAS)
· International Building Code (IBC)
· International Residential Code (IRC)
· National Fire Protection Association (NFPA)
· Uniform Building Code (UBC)
All construction projects in the United States must meet at minimum, IBC and IRC standards. Prior to beginning construction, homeowners and contractors should check with the local building official in their area to ensure that their project meets all code requirements and adheres to any local ordinances in place when applying roof or sidewall product.
The classification for uplift resistance is expressed in pounds per square foot. The test method subjects a minimum 10 by 10 ft. test sample to various short term (1 minute interval) static pressures which represent the uplift forces imposed on roofing systems securement to a specified roof deck when exposed to high velocity winds. In other words it tests how well shakes and shingles hold up when subjected to high winds. It measures the degree to which the roofing material is uplifted from the roof deck.
The classifications for impact resistance are expressed as Class 1, 2, 3 or 4 which relate to a roof covering’s ability to withstand impacts from 1¼, 1½ , 1¾ and 2″. diameter steel balls, respectively. Certi-label™ 24″ x ¾” Handsplit and Resawn shakes carry a Class 4 impact resistance rating, Certi-label™ Handsplit and Resawn shakes 24″x ½” carry a Class 3 impact resistance rating. If you live in a hailstorm prone area there are some insurance underwriting companies that will offer a discount on your premium if you use a roofing material that is impact resistance rated. In the state of Colorado for instance, Western United offers a scaled discount depending on the impact resistance rating. Identifying the difference in naturally weathered and storm damaged cedar roofs is sometimes a difficult task. It takes a trained eye to assess a cedar roof and determine if it is in fact damaged due to hail, or if it is just naturally weathered. It also takes a trained eye to determine the amount of repair required.
Certi-Split® shakes 180 PSF
A subsequent report by a Florida Registered Professional Engineer converted the PSF numbers into miles per hour figures using the analytical method for wind design of roof cladding set forth in Section 6 of ASCE 7-98 (American Society of Engineers). Results, using no safety factors, are as follows:
Certigrade® shingles withstood wind speeds of 173 MPH
Certi-Split® shakes withstood wind speeds of 245 MPH
It should be noted that these calculations were conducted for a specific house in the Dade County area of Florida. When converting from PSF to MPH using ASCE 7-98 results will vary depending on many factors including building height, location, roof slope, environment etc. Be advised that all design parameters, assumptions and limitations of use set forth in the Florida engineer’s report are necessary components of further interpretation.
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