Historic Preservation - Technical Procedures
Repairing Pinch Cracks In Long Copper Gutters
Hspg Prepared For Nps - Sero
Thermal And Moisture Protection
Repairing Pinch Cracks In Long Copper Gutters
REPAIRING PINCH CRACKS IN LONG COPPER GUTTERS
A. This procedure includes guidance on patching pinch cracks
in copper gutters. GENERALLY, THIS WORK SHOULD BE
ACCOMPLISHED BY A EXPERIENCED ROOFING CONTRACTOR.
B. Pinch cracks start as a small wrinkle in the angle
between the bottom of the gutter and the upstand.
Repeated expansion and contraction cycles enlarge the
wrinkle and pinch the folds in the copper, causing the
metal to harden severely and eventually crack.
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 prior to performing
this procedure and should be followed, when applicable,
along with recommendations from the Regional Historic
Preservation Officer (RHPO).
A. Shop Drawings: Before repairing or replacing gutters,
prepare a working drawing showing sheet length and width
between seams. Prepare typical exposed seam details and
fastening patterns for guidance. Submit to RHPO for
1.03 DELIVERY, STORAGE AND HANDLING
A. Packing and Shipping: For replaceable material: protect
gutters and downspouts from damage at all times during
handling, installation, and operation of the building.
B. Acceptance at Site:
1. New sheet metal shall be delivered on the job
carefully packed. Inspect each piece immediately
before installation, and do not use the pieces
which have observable edge damage or face
2. Manufacturer's delivery or job markings on the
sheet metal, and adhesives for manufacturer's
labels, shall either be a neutral or slightly
acidic material. In no case shall such material be
alkaline; any staining of the sheet metal by
alkaline materials will be cause for the rejection
of the piece.
C. Storage and Protection:
1. Salvaged historic material shall be carefully
packed and stored under cover and in the building
away from working or traffic areas. Mark salvaged
material with the year of removal.
2. Keep uninstalled roof gutters and downspouts under
cover, dry, free from scratches, condensation and
distortion during delivery, storage and handling.
1.04 PROJECT/SITE CONDITIONS
A. Environmental Requirements: Do not remove gutters from
structures when rain is forecasted or in progress.
A. Quarter-hard temper copper
B. Stop-end expansion joints
A. Safety belt or harness
B. Ladders and scaffolding
C. Chicken ladder
D. Carpenter's level
E. Mason's level
F. Sheetmetal snips, tongs and clamps for cutting and
1. At the end of each work day, provide building
protection for any exterior gutter element removed
for repair or replacement, if water penetration is
2. Landscape work adjacent to or within the ground
work areas for gutter maintenance shall be
protected. Provide plank barriers to protect tree
trunks. Tie-up spreading shrubs, and cover as
necessary, allowing the plants to breathe. Remove
the covering and ties at the end of each work day.
Set scaffold ladder and legs away from plants.
Pruning requests shall be directed to the RHPO.
3. Keep trees trimmed to prevent branches from
scuffing or moving downspouts.
4. Set ladders on an incline whereby the bottom of the
ladder is approximately 25% of the height from the
base of the building. Do not rest ladders on
3.02 ERECTION, INSTALLATION, APPLICATION
A. Repairing pinch cracks: Dressing the wrinkled copper
flat and soldering a copper patch over the crack may be
ineffective as the cracking will eventually transfer
1. Use quarter-hard temper copper instead of the usual
fully annealed material to enhance the strength of
2. Provide stop-end expansion joints at high points
3. Join or weather the gutter to the roof sheets and
flashing by "sliding" welts or overhanging aprons.
4. The permissible length varies with the thickness of
the copper used, the width of sole, and the shape
of the gutter.
5. With stop-end expansion joints between every length
of lining, each section of the gutter must be
NOTE: Double cross welts have the ability to
absorb longitudinal expansion movement, but they
are generally not suitable for this purpose because
the welts are not sufficiently watertight.
Furthermore, if ponding water develops and sits in
contact with the welts for extended periods, water
may be drawn through the welt.
B. To make welts watertight, make a dummy welt.
1. Reproduce the folds of a double-lock cross welt in
a long strip of copper without actually cutting it
into separate pieces, to form "dummy welts" across
2. Space the dummy welts at a maximum of 4'-3" to
provide adequate accommodation for the thermal
movement to the gutter lining between drips.
END OF SECTION