CEMP-ET
TI 809-53
01 May 1999
(7) Temperatures During Construction. Consider the temperatures during construction to verify
that the clips can accommodate the maximum thermal expansion expected when the building is put into
service.
b. Pre-roofing Conference. A conference should be held prior to construction especially for unusual
applications. Representatives of the designer, user, roofing contractor, general contractor, materials
manufacturer, field inspector, and other related subcontractors should be present. Discussion should
include support of mechanical equipment, penetrations, transitions, and terminations.
c. Shop Drawing Submittals. The manufacturer will normally provide detailed drawings of all
connections. These should be appropriate for the project's wind and structural design requirements. See
NRCA Roofing and Waterproofing Manual and the SMACNA Manual for typical details required.
d. Design Submittal Requirements and Checklist. The designer should specify design loads,
resource documents (e.g., ANSI/ASCE 7-95), and system type (e.g., structural vs. non-structural,
watershedding vs. waterproof) using the guidelines in this EI. The metal system should be designed as a
complete system to meet these requirements. Evidence of meeting ASTME1592 and UL 580 should also
be required.
e. Field Review and Observation. These systems each have unique application techniques and tool
requirements. A copy of the manufacturer's erection manual should be provided to the field inspector for
examination.
9-5. MAINTENANCE CONSIDERATIONS.
a. General.
(1) Coatings. Zinc-aluminum, aluminum, and PVDF (poly-vinylidene difluoride) coated steel
should remain corrosion free for 20+ years. However, gouges and scratches that remove the coating can
result in corrosion if not field coated. Manufacturers can provide touchup materials.
(2) Surface Contamination. Ferrous debris left on the roof panels (such as iron shavings from
metal cutting operations) will corrode and cause staining of the zinc-aluminum and all-aluminum coatings.
Periodic cleaning of leaves, pine needles, and other debris is recommended.
(3) Copper Salts. Copper salts, such as that carried by HVAC condensate water, will attack
zinc, aluminum, and zinc-aluminum alloy coatings. Because of this, run condensate lines from copper
cooling coils directly into drains. Washing of copper salts from up-slope copper flashings will also degrade
zinc alloys.
(4) Durable Metals. Avoid the use of galvanized steel counterflashings as they are far less
durable than zinc-aluminum and Polyvinylidene Fluoride (PVDF) coated materials. Galvanized iron will
become unsightly as it rusts and stains the zinc/aluminum coating. Only durable fasteners recommended
by the manufacturer should be used for the same reason.
b. Repair or Replace. The most common problems with metal roofing are:
(1) Corrosion. When the protective coatings fail the base steel will rust. Clean by sandblasting or
sanding followed by rust inhibiting primer and topcoat. For PVDF coatings, adhesion of retreatments is a
problem. Consult with the system manufacturer for suitable primers and coatings.
(2) Differential Panel Movement. Differential panel movement may cause fastener hole
enlargement of through-fastened panels. A variety of treatments are available, most of which embed
9-8
Previous Page
