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Ludowici Interlocking Tile Installation Manual <br />10 www.ludowici.com <br />Roof Deck <br />A design standard for roofing decks is to have a maximum <br />deflection of L/240 between supports. A deck will be <br />exposed to live and dead loads. A live load is one that <br />will only be exerting pressure on the roof deck for a short <br />time. Example; Snow or wind loads. A dead load is one <br />that will exert a constant pressure to the roof deck; i.e., <br />underlayments, tile and battens. <br />Fastener Pullout Resistance: Minimum average fastener <br />pullout resistance for clay roofing tile is 180 lbs. with no <br />single value less than 170 lbs. Greater pullout values may <br />be required depending upon the predicted aerodynamic <br />moment expected for the tile shape, building shape and the <br />proximity to the coastline. An engineer should be consulted <br />to assure local building code compliance. <br />For Board Plank Deck: Use well-seasoned plank board <br />(1" full thickness, maximum 6" nominal width) that is not <br />prone to warping, cupping or twisting. <br />For Plywood Deck: APA rated plywood is required for a <br />minimum of 3/4" thick wood decking and must be rated <br />for structural use as roof sheathing. The expansion crack <br />between panels shall be at least 1/16" but no greater than <br />1/8". H-clips are to be used when rafters are spaced greater <br />than 16" on center to hold the side joints of the plywood <br />together between supports. Unsupported end joints must <br />be blocked. <br />Nailable Concrete Decks: Nailable concrete decks over <br />time may lose their plastic nature, which allows direct <br />nailing. For old decking material, a pullout test should be <br />performed to determine the usefulness of the deck and the <br />appropriate fastener. An engineer should be consulted to <br />assure local building code compliance. <br />Non-Nailable Concrete Decks: For concrete decks that <br />will not accept direct nailing, nailer boards are required. <br />Attachment strips that allow the tile to be fastened to them <br />should be pressure treated wood. These may be a board and <br />batten system or pressure treated wood strips. Other means <br />Weight <br />Proper roof framing is required to carry the weight <br />of a tile roof. The weight of one square (100 sq. ft.) of <br />Interlocking tile will range from 598 pounds to over 1,025 <br />pounds. The weight of the roof tile is determined by the <br />type and size of the tile and the exposure of each course <br />of tile. Reducing the exposure of the tile will increase the <br />roof load. <br />The weight of the underlayment, fastening system, roof <br />accessories and trim tile also needs to be considered <br />when determining the total weight. Check dead load <br />allowances of the applicable local building codes. <br />It is recommended that the structural design of the roof <br />be evaluated by a registered engineer to determine that <br />it can support the load; most building codes require an <br />engineering review. Getting a written letter of approval is <br />suggested and may be required by local building codes. <br />If the installation is in a region of seismic activity or heavy <br />wind load, local building codes must be consulted for <br />additional requirements. <br />Roof Slope <br />Ludowici Roof Tile’s recommended minimum slope <br />requirements for Interlocking tile is 3:12. No clay tile <br />roofs are to be installed below a roof slope of 3:12. <br />There is no maximum slope requirement for tile roofs. <br />However, on extremely steep (above 19:12) or <br />vertical applications, wind current may cause the <br />tiles to rattle. To avoid this, set the butt of each tile <br />with a bead of sealant where it will not be seen. <br />Before Getting Started