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Historic Preservation - Technical Procedures
Repairing A Detached Standing Seam On A Copper Roof
Hspg Prepared For Nps - Sero
Thermal And Moisture Protection
Sheet Metal Roofing
Repairing A Detached Standing Seam On A Copper Roof
REPAIRING A DETACHED STANDING SEAM ON A COPPER ROOF
THIS PROCEDURE SHOULD ONLY BE PERFORMED BY AN EXPERIENCED
PROFESSIONAL AND ONLY UPON APPROVAL FROM THE REGIONAL HISTORIC
PRESERVATION OFFICER (RHPO).
THIS PROCEDURE SHOULD BE PERFORMED UNDER THE DIRECTION OF AN
HISTORICAL ARCHITECT OR ENGINEER TO DECIDE THE MOST EFFICIENT AND
LEAST DESTRUCTIVE MANNER FOR EXECUTING THE WORK.
A. This procedure includes guidance on repairing a detached
standing seam on a copper roof. GENERALLY, THIS WORK
SHOULD BE ACCOMPLISHED BY AN EXPERIENCED ROOFING
CONTRACTOR. Though this technique applies specifically
to copper roofing, the same principles are also
applicable to other types of standing seam metal roofs.
B. Standing seams may become detached for several reasons:
1. If the fasteners securing the cleats have pulled
a. This is especially true when copper tacks have
been used instead of the proper nails.
b. Tacks are tapered throughout their length and,
therefore, even the slightest withdrawal will
seriously reduce their hold in the decking.
c. The normal shrinkage of wooden deck members
due to natural drying out will aggravate the
2. If a seam has an insufficient number of cleats or
some existing cleats coincide with joints or splits
in the decking. This, combined with localized high
wind turbulence may cause individual seams to
a. Cleats should be spaced at a maximum of 1'-3"
on center, and fastened to the deck by two
copper nails close to the turn up.
b. Cleats spaced too far apart can break under
the repeated strain of wind loading.
C. See 01100-07-S for general project guidelines to be
reviewed along with this procedure. These guidelines
cover the following sections:
1. Safety Precautions
2. Historic Structures Precautions
4. Quality Assurance
5. Delivery, Storage and Handling
6. Project/Site Conditions
7. Sequencing and Scheduling
8. General Protection (Surface and Surrounding)
These guidelines should be reviewed before performing
this procedure and should be followed, when applicable,
along with recommendations from the RHPO.
A. Anneal--operation of heating and cooling the metal to
soften it and make it less brittle.
B. Cleats or Clips--copper strips, cut to lengths to suit
roll or seam, placed at intervals and securely fixed to
the roof base, the ends being welted in with the edges of
the sheets to hold the copper roofing in position.
C. Standing seam--a double welted joint formed between the
sides of adjacent bays and left standing.
D. Turn up--where the two adjacent edges of metal sheets are
brought together vertically and folded over.
E. Welting--joining copper sheets at their edges by folding
together. Welting may have single or double folds, such
joints being termed single or double welts respectively.
1.03 SYSTEM DESCRIPTION
A. A metal roof in good condition has not failed due to
withdrawal of nails from the decking, nails have not
pulled through the holes in clips, has sufficient clips
provided in the seams, and that no breakage of clips has
1.04 PROJECT/SITE CONDITIONS
A. Environmental Requirements:
1. Wet weather: Do not begin to repair metal roof in
misty or rainy weather. Do not apply metal roofing
to wet roof sheathing.
2. At the end of each work day, provide building
protection for any exterior roofing element removed
for repair or replacement.
A. Wash copper metalwork at regular intervals to remove
corrosive elements, especially areas which are not
effectively washed by rainfall to remove dust, grime, and
soot. Carry out such cleaning with materials
noncorrosive to copper or the copper patina.
NOTE: AVOID CLEANING COPPER WITH ALKALINE SOAPS THAT DO
NOT CONTAIN SODIUM HYDROXIDE, DETERGENTS CONTAINING
PYROPHOSPHATES SUCH AS "TIDE" OR AMMONIA SOLUTIONS.
THESE WILL ATTACK THE COPPER.
B. Clean the roof of dirt build-up annually by rinsing with
clean, clear water.
C. Keep the roof clear of debris, and trim all overhanging
branches that might cause mechanical damage.
D. Inspect for and eliminate ant hills and/or bird droppings
that can corrode sheet metals.
1. Bird droppings can cause localized corrosion on
copper because of the acids found in the droppings.
2. Remove droppings using a wooden spatula; wash
copper surface with a neutral detergent.
3. Rinse with distilled water and wipe dry with a
clean soft cloth, to prevent water spots and
CAUTION: DO NOT USE BLEACH TO REMOVE BIRD EXCREMENT.
BIRD DROPPINGS CONTAIN AMMONIA AND IF MIXED WITH BLEACH
CAN FORM TOXIC GASES.
E. Inspect the secureness of cleats and fasteners and the
condition of the sheet metal after particularly heavy
F. Never use any black goop (asphaltic roofing compound) or
caulk to seal joints on a metal roof. Asphalt attacks
metal roofing, and no caulk lasts long enough for this
A. Copper nails - large, flat head nails with barbed shank
B. Copper cleats
A. Soldering iron to anneal edges of sheet metal
(temperature of iron should not exceed 500 degrees)
B. Vise-Grip Crimpers, wood block and mallet, or metal
C. Chicken ladder, safety belt or harness
D. Protective gloves and gear
E. Straight snips for cutting straight or curved lines in
sheet metal 24 gauge or lighter
F. Handy Tongs for bending the edges light sheet metal
A. Nails in the cleats that have withdrawn from the decking,
may be unable to fall out of the cleat because they are
covered by sheet metal. As a result, they may turn on
their side and prevent the seam from either resting on or
being pressed flat against the top of the decking.
B. To decide if there are not enough cleats, note the
positions of the cleat in the opened seam, and then
closely examine the exterior of the other seams at
approximately the same intervals in their length. The
additional thickness of the folded cleat frequently
produces a slight bulge in the seam that is not too
difficult to detect.
C. Poorly positioned fasteners, i.e., nails at the ends of
the cleats instead of close to the turn up may allow a
standing seam to be raised from the decking without the
use of undue force.
3.02 ERECTION, INSTALLATION, APPLICATION
A. Using soldering iron, heat seam (anneal) as necessary to
open it sufficiently to insert new cleats as required.
B. Fix new cleats at appropriate intervals and with proper
fasteners, taking care to nail near the turn up.
C. Re-heat edges of sheet as required to make them workable.
D. Dress upstands together and fold over (welt) as required
to finish seam. Match existing appearance.
END OF SECTION