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Ludowici Interlocking Tile Installation Manual <br />11www.ludowici.com <br />of attaching tile to a concrete deck include wire-tie systems, <br />foam adhesive and expanding nail-in anchors. <br />NOTE: Ludowici does not recommend applying tile over <br />spaced board sheathing or open battens. <br />Underlayment <br />Most problems with water-shedding roof installations occur <br />from water that migrates through the joints of the tiles <br />through capillary action, wind driven rain and runoff or ice <br />damming. Because of this possibility, the underlayment <br />is critical to the success of the roof. It is the architect or <br />building owner’s responsibility to select an underlayment <br />product that is suitable to specific location, climate, roof <br />pitch and attic ventilation. When selecting an underlayment <br />remember that Ludowici roof tiles are expected to last over <br />75 years so the underlayment should be of a comparable <br />lifespan and quality. <br />Ludowici recommends the following for minimum <br />underlayment: • All decks shall be covered with two layers of No. 30# <br />asphalt-impregnated roofing felt or one layer of No. 43# <br />coated base sheet or one layer of Ice and Water Shield. <br />NOTE: When using non-breathing Ice and Water Shield <br />underlayments to cover the entire roof, the attic space <br />MUST be properly ventilated to prevent moisture buildup.• All hips, valleys, rakes and ridges shall be covered with a <br />waterproof underlayment, example; Ice and Water Shield <br />or two layers of No. 43# coated base sheet. • For proper ice dam protection a layer of Ice and Water <br />Shield underlayment should be installed from the eave to a <br />point 24" beyond the inside of the exterior wall. See page <br />14 for more information on ice dam protection. <br />NOTE: Roofing felt should meet or exceed ASTM standards <br />D226/D2626. Self adhered Modified should meet or exceed <br />ASTM D1970. <br />Type Pros Cons <br />Asphalt <br />Roofing Felt <br />• Long track record <br />• Well suited for most applications <br />• Readily available <br />• Breathable <br />• Less expensive than Synthetics or Self Adhered <br />• Doesn’t seal around the nail holes <br />• Not as effective on lower pitches <br />• Can tear <br />• Not suitable for long duration exposure directly <br />to the elements <br />Ice & Water Shield <br />(Self Adhered <br />Polymer-Modified <br />Bituminous Sheet) <br />• Rubberized material seals around nail holes <br />• Self adhering materials creates a more monolithic <br />water barrier <br />• Ideal for low slope applications <br />• More expensive <br />• Non breathing requires good attic ventilation <br />• Can be damaged by UV if exposed for 180+ days <br />Synthetic <br />Underlayments <br />• Purported life span and durability <br />• Some Synthetics are breathable <br />• Unproven. Most products have been on the mar- <br />ket less than 20 years. <br />• Two to three times cost of felt <br />Chart 11.1 Underlayment Characteristics