Atlas Nail Base should be installed directly over the vapor retarder that has been applied over the deck. Atlas requires the use of Atlas Nail Base fasteners. Refer to Atlas Guide Details for Nail Base and Vented-R Insulation for fastening patterns and other application recommendations.  Additional installation recommendations for Atlas Nail Base Fasteners are as follows:

• The fasteners should be installed using an 1800-2500 RPM (max) screw gun with a hardened #3 square drive bit.  Standard electric drill guns are not recommended for installation of the Atlas Nail Base Fastener.
• Metal Decks are acceptable deck types provided they are 22 ga (min.) and 19 ga (max.).  Be sure to detemine the gauge of the deck.  If it is 16 ga, consult the Atlas Technical Department.

Heavy snow and ice loads, very steep pitches, high humidity structures, or very high wind areas may necessitate custom fastening patterns and design. For design conditions beyond those contained in the Guide Details, a professional engineer or architect should be consulted for those special applications. Cover with Atlas No.15 or No. 30 roofing felt. Use only enough nails as required to keep felt in place. Any insulation that has become wet must be replaced with dry product prior to applying the roof coverings. Atlas also offers a wide variety of roof shingle products including three-tab and laminated shingles as well as felts and accessories.

Vapor Retarders

Moisture vapor tends to migrate from warmer to cooler areas. In building construction, vapor retarders are used to inhibit or block the passage of moisture into walls or roofing assemblies. Vapor retarders also serve as air barriers to limit the movement of moisture-laden air from the interior to the exterior. To determine whether a vapor retarder is necessary, calculations on occupancy and relative humidity inside the building and the outside temperatures during the various seasons must be performed. Consult the NRCA Roofing and Waterproofing Manual (Fifth Edition) for more information regarding vapor retarders.

The designer must be aware of the actual conditions of the specific installation. The designer has the responsibility to determine whether a vapor retarder is required and what type should be used; however, Atlas strongly recommends the use of a vapor retarder with a perm rating of 0.5 or less (i.e., 4 mil polyethylene minimum) on all projects except those in extreme cooling climates. The vapor retarder should be placed over the solid deck. This recommendation is made to prevent excessive moisture (from construction materials or design conditions) from migrating through the roof assembly and causing condensation within the roof system. For more information on vapor retarders, refer to Atlas Guide Details for Nail Base and Vented-R Insulation.