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ROOF -CEILING CONSTRUCTION <br />Roof -ceiling construction can generally be broken into two classes: single - <br />joist systems and attic -space systems. The use of attic -space systems is <br />generally required in Minnesota because of the climate and the Minnesota <br />Energy Code. However, information on both systems is included here. <br />Venting of the attic space as required by the building code will reduce the <br />acoustical effectiveness of construction as noted in the table. <br />BASIC BUILDING ELEMENTS <br />Single -Joist Roof <br />(STC 34 - 49) <br />4- <br />Attic-space Systems <br />(STC 41 - 45) <br />STC Ratings for Basic Roof -Ceiling Construction (Based upon EWE• data) <br />Attic space is assumed to be vented and insulated; a single -joist system <br />is assumed to be unvented. <br />Ceiling Material and STC Rating <br />Single -Joist Systems Attic -Space Systems <br />1/2" Gypsum Exposed 1/2" Gypsum Exposed <br />Roof Material Board Joist Board Joist <br />Wood shingles 45 34 41 43 <br />Composition shingles 49 40 42 44 <br />Clay or concrete tiles 57 45 43 45 <br />Build-up roofing 49 37 41 43 <br />1/3" wood -sheet metal -- 36 41 43 <br />*External wall rating. See page 42, Appendix C. <br />9 <br />