Installation Instructions

GlassMaster General Instructions - Ardmore, OK & Hampton, GA
Atlas Roofing
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: 2:12-4:12 (51mm/305mm) on slopes of 2" to 4" rise per foot, a double
layer of approved underlayment over the entire deck surface is required. Starting with a 19" wide
strip at eaves and overhanging the eaves 1/4" to 3/8", cover the first 19" course with a full 36" wide
strip. Expose the first course 17" and continue up the deck with 36" wide strips, lapping each
course 19" over the preceding course - providing a 17" exposure. End laps for low slopes shall be of
at least 12” overlap and staggered 6 feet apart. Install drip edge over the underlayment at the rake
and beneath the underlayment at the eaves. WeatherMaster® Granular is highly recommended as
the underlayment for Low Slope (2" in 12" slope to 4" in 12" slope) to cover the entire deck prior to
installing shingles.
5. FLASHING
All flashing should be in place before shingles are installed. Cap flashings of sheet metal and base
flashings of metal or mineral surfaced roll roofing should be used at vertical surfaces such as
chimneys, skylights, vents, walls, etc. All flashings should be sealed with asphalt plastic cement.
Consult the Residential Asphalt Roofing Manual published by the Asphalt Roofing Manufacturers
Association (ARMA) for details concerning specific methods and types of flashing installation.
6. ICE DAM PROTECTION
Eave and rake edge waterproof flashings must be installed per local building codes and where there
is a possibility of icing along the eaves and rake edges causing a potential for ice damming and a
backup of water. Atlas’ WeatherMaster® Granular Underlayment, or equivalent must be applied
directly over the decking according to application instructions provided with the product, and local
building codes. The waterproof flashing material must extend up the roof at least 24” beyond the
interior warm wall line, and in areas of severe icing, at least up to the highest water level expected
to occur from ice dams. If the overhang requires flashing wider than 36”, the horizontal lap must be
located on the overhang area and cemented or sealed. End laps must be 12” (minimum) and
cemented/sealed. WeatherMaster® Granular Underlayment, as supplied by Atlas, is recommended
as the first layer of Ice Dam Protection. WeatherMaster® Granular Underlayment conforms to ASTM
D-1970.
7. VALLEYS
Valleys must be installed before GlassMaster® 30 shingles are applied. Closed Cut Valley: Over felt
underlayment, apply a 36" wide mineral surface asphalt roll roofing (with granule side up) or
smooth surface asphalt roll roofing centered in the valley, nailing 2" from outer edges only. Apply
all shingles on one side of valley and across center of valley, a minimum of 12". Nail a minimum of
6" away from the center line of the valley on the unshingled side and strike a chalk line 2" from the
center line on the un-shingled side. Apply shingles on the unshingled side up to the chalk line and
trim. Do not cut the underlying shingle. Cut upper corners of the shingle, cement and nail. See
Diagram #1.
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