Installation Instructions

3.) ROOF DECK
These instructions are for the application of Atlas asphalt shingles to nominal 3/8” or 7/16” thick American
Plywood Association (APA/TECO) rated, code approved plywood, OSB decks or minimum ¾" actual
thickness, wood decking . The plywood or non-veneer (OSB) decks must comply with the roof deck
specifications of APA/TECO. Solid wood decking must be well seasoned, not over 6" (nominal) width, and
fastened securely to each rafter. The deck surface must be clean, bare, gap free and flat. Pinnacle® Pristine
shingles must not be applied to any surface other than roof deck types described here. Atlas also honors its
Shingle Limited Warranty when Atlas shingles are installed on the Atlas CrossVent® Nailable Insulation panels.
Atlas will not be responsible for the performance of its shingles if applied directly to non-vented, insulated
decks composed of perlite board, plastic foam, fiberboard, gypsum plank, lightweight concrete, cementitious
wood fiber, or similar materials or to any decks with insulation installed directly to the underside of the decking,
with the exception of CrossVent® Nailable Insulation. Spray foam insulation applied directly to the bottom of
the decking will void the warranty. Atlas shingles may be installed over a roof system containing a radiant
barrier material if: 1. the required full, flow through ventilation is maintained directly under the decking
material in all cases, 2. the radiant barrier material is highly vapor permeable ( > 2 perms), and, 3. the radiant
barrier is installed on the underside of or below the decking – not used as an underlayment above the decking.
Spray--on types of below deck vapor permeable radiant barriers will be considered only on a job by job basis,
and only if tests confirm > 2 perms or greater vapor permeability.
4.) UNDERLAYMENT
Atlas highly recommends the use of high performance, ASTM 6757 compliant - Gorilla Guard® Everfelt™ or
Summit® proprietary underlayment products for long term roof system performance and WeatherMaster®
products self-adhering, waterproofing underlayment for critical areas, such as valleys and eaves. Atlas does not
approve the use of any self-described, metalized or metal containing category of “Radiant Barrier”, as an
asphalt shingle underlayment installed above the deck. Use of these types of radiant barrier would void the
shingle warranty. Underlayment must be applied flat and unwrinkled. Building codes vary with geographic
areas, and the installation must comply with local building codes or shingle manufacturer’s requirements,
whichever is stricter. Shingles should be applied as soon as possible after the application of organic
underlayment felt, which is not intended for prolonged exposure. Atlas recommends that the shingles be applied
the same day as the felt underlayment application to avoid wetting and wrinkling. If an underlayment is used for
prolonged dry-in, Atlas recommends Summit® Synthetic Underlayment as the dry-in underlayment, for up to 6
months exposure.
Standard Slope Application: Proper application requires that a single layer of approved underlayment be applied
to decks with slopes 4:12 (> 18.4°) up to 21:12 (<60°) and consistent with all applicable building codes. This
approved underlayment is a required roof assembly component to maintain a Class A fire rating of the deck
assembly. Install underlayment over the entire deck, parallel to the eaves, overhanging 1/4" to 3/8", with
fasteners placed 2" from the deck edge, 12" O.C. across the lower edge and with 2" overlap parallel to eaves
and with 4" min. end lap, parallel to the rake. Underlayment end laps shall be staggered 6 feet apart from the
adjacent courses. Corrosion-resistant drip edge should be placed over the underlayment at the rake and beneath
the underlayment at the eaves.
Low Slope Application: 2:12 (>9.5°) up to 4:12 (<18.4°) (51mm/305mm) on slopes of 2" to 4" rise per foot, a
double layer of approved underlayment over the entire deck surface is required. WeatherMaster Ice & Water
products are highly recommended as the underlayment for low slope roofs to cover the entire deck prior to
installing shingles. As an alternative option, a double layer of approved underlayment can be installed over the