Metal Roofing Panels
Installation Guide for Delta Rib
™
, Delta Rib
™
III, Nor-Clad
®
, Strata Rib
®
& 2½” Corrugated
®
4 March 2024 • ASC Building Products
www.ascbp.com
Roof Preparation
ASC Building Products Metal Roofing can be used in both new
construction and retrofit roofing applications. We recommend the
installation of metal roofing over a continuous rigid substrate such
as plywood/OSB, or over spaced supports. Contact ASC Building
Products for additional information.
The following steps need to be taken to prepare the roof for
installation of metal roofing panels:
New Roofs:
1. Make sure there are no nails or other objects protruding from
the substrates that might puncture the underlayment or the roof
panels. Clean all debris from the roof.
2. Check all details for possible roof penetrations which must be
added to the deck prior to roof panel installation.
3. Cover the entire roof deck with a minimum of 30 lb asphalt-
saturated felt paper. Some synthetic underlayments may be used
in place of felt with ASC Building Products’ roofing. Installer must
ensure they meet the minimum standards of 30 lb felt and that
the underlayment manufacturer has approved them for use with
metal roofing. For applications over spaced framing other types
of moisture barriers may be required. For Class A fire resistance,
see notes below. For installation begin at the eave and roll the
underlayment horizontally (parallel to the eave). Allow each con-
sec u tive course to overlap the previous one 3 inches. Overlap the
ends a minimum of 6" (See illustration #1). Areas of underlayment
that have torn should be replaced or repaired prior to installation
of the metal roof.
Illustration No. 1
6" END LAP
3" SIDE LAP
30# FELT PAPER
UNDERLAYMENT
Constructions Requiring
Class ‘A’ Fire Resistance:
Panel: ASC Building Products’ steel roof panels.
Barrier Sheet (one of the following):
• GAF VersaShield
®
Underlayment
• Firestone GLAD-GARD™ SA-FR
• Polyglass Polystick
®
XFR
• Georgia-Pacific DensDeck
®
Rooboard
Additional Ply Sheet (optional): Any UL Classified Type G1, G2 or
G3 base/ply sheet, Type 15, 20 or 30 felt or UL Classified Prepared
Roofing Accessory (TGDY) or ASC Building Products’ “AEP Span
Underlayment HT”.
Substrate: 15⁄32” min. plywood or 7/16” min. OSB
Notes:
• Obey all local code requirements.
• Class A assembly requirements noted above per UL
listing TGFU.R21182. Refer to UL listing for specific
construction limitations.
4. Place an alignment line along the gable end where the first roof
panel will be installed. This line must be parallel to the gable
edge of the roof deck and square with the eave line. Check the
roof for squareness by making a 3' line across the eave. (See
illustration #2).
DIRECTION OF
PANEL APPLICATION
LINE MUST BE
SQARE WITH EAVE
1/4" IN FROM
THE GABLE
ALIGNMENT LINE
Illustration No. 2
Completing the 3' x 4' x 5' triangle should place the 4' edge of
the triangle parallel with the gable. The first roof panel will be
placed parallel with this line. Slight variations or out-of-square
conditions up to 3" can be covered by the gable trims shown on
page 18.
5. It is very important to measure the entire length of the roof from
gable to gable. Correct placement of the panels will allow the
panel’s ribs on each side to be covered by the gable lashing shown
on page 18. This will create a symmetrical appearance on both
gables. Should this be impractical, the adjustable gable detail on
page 30 can be used.
Note:
In areas where snow, ice, and heavy rain conditions exist, a high
temperature cold-applied rubberized underlayment , like AEP
Underlayment HT, should be used in lieu of felt in the valleys. Felt
on the remainder of the roof will lap over the membrane where
the two meet. See Valley page 13.
Existing Roofing:
Some jurisdictions will allow reroofing over existing roofing without
the need for tearoff. Check with your local codes or building
department for your specific requirements.
For best results, Roofing requires a relatively smooth and lat
substrate. Application over rough and/or uneven surfaces is not
recommended, for example, wood shingles. If the roof is to be
stripped down to the existing decking, follow the procedures for
new roofs on page 4. Be sure to check the existing roof and repair
any damaged areas prior to installation of the new roof system.
Note:
Do not apply metal roofing over roofs with structural
damage or trapped moisture.