Technical Procedures Disclaimer
Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.
We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. Specifications should only be applied under the guidance of a qualified preservation professional who can assess the applicability of a procedure to a particular building, project or location. References to products and suppliers serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or method is the best alternative or compliant with current environmental regulations and safety standards.
A. This procedure provides supplemental guidelines to be used when specifying any type of repairs to copper metal work. Guidelines for shop drawings, qualifications for subcontractors, materials and finishes, shop assembly, and general guidelines for installation are included.
B. These guidelines may be used in conjunction with the following procedures:
- 07602-01-R "Repairing Pinch Cracks in Long Copper Gutters".
- 07610-02-R "Installing a Transverse Expansion Joint in a Standing Seam Copper Sheetmetal Roof".
- 07610-03-R "Repairing a Bowing Sheetmetal Roof".
- 07610-04-R "Repairing a Wind-damaged Copper Sheetmetal Roof Ridge and Installing a New Ridge Cap".
- 07610-05-R "Repairing Holes in a Sheetmetal Roof".
- 07610-06-R "Repairing Corroded Copper Sheetmetal Roofing Materials"
- 07610-12-R "Repair of Star Cracks in Copper Roofs".
C. Procedures for the repair of copper metalwork shall include all work, materials and equipment required to:
- Remove required ornamental metalwork and securely re-install ornamental metalwork to its original place and position.
- Repair ornamental metalwork with RHPO approval.
- Provide for historical photos of work done.
D. See 01100-07-S for general project guidelines to be reviewed along with this procedure. These guidelines cover the following sections:
- Safety Precautions
- Historic Structures Precautions
- Quality Assurance
- Delivery, Storage and Handling
- Project/Site Conditions
- Sequencing and Scheduling
- 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. Product Data: Submit product data for each product used in ornamental metalwork, including finishing materials and methods to RHPO for prior approval.
B. Shop Drawings: Submit to RHPO three copies of shop drawings showing fabrication and installation of ornamental metalwork including plans, elevations and details of components and attachments to other units of work. Indicate materials, profiles of each ornamental metalwork member and fitting, joinery, finishes, fasteners, anchorages and accessory items.
- Include setting drawings, templates, and directions for installation of anchor bolts and other anchorages to be installed as unit of work of other sections.
- Where installed products are indicated to comply with certain design loadings, include structural computations, material properties, and other information needed for structural analysis which has been prepared by, or under the supervision of, a qualified professional engineer.
C. Samples: Submit to RHPO samples for initial selection purposes in form of conservator's color samples of patina consisting of actual units or sections of units showing full range of patina colors and other finish characteristics for each item indicated below.
D. Submit to RHPO samples for verification purposes of each type of metal finish required, prepared on metal of same thickness and alloy indicated for final unit of work. Where finishes involve normal color and texture variations, include sample sets composed of two or more units showing full range of variations expected.
E. Submit to RHPO conservator/installer certificates signed by Contractor certifying that conservator/installers comply with requirements specified under "Quality Assurance" article.
F. Submit to RHPO qualification data for firms and persons specified in "Quality Assurance" article to demonstrate their capabilities and experience; Include list of completed projects with project name, addresses, names of architects and owners, plus other information specified.
- Contractor shall ensure that the conservator takes one 8" x 10" black and white photo "before" shot of each metalwork assembly as required. "After" photos in the same format shall be taken from the same locations and of the same items after all items are re-installed and conservation is complete. Submit two copies and the negatives of each shot. All copies shall be archivally sound.
- Submit one set of color slides showing de- installation, progress of repair and restoration, and re-installation, to RHPO at close of contract. Views shall be chosen by conservator. The slides shall present a picture story of the entire conservation process.
- Label all photos and slides in such a manner that photo location and process shown corresponds to label.
1.03 QUALITY ASSURANCE
- Conservator/Fabricator Qualifications: Firm experienced in successfully producing ornamental repousse metalwork similar to that indicated for this project, with sufficient production capacity to produce required units without causing delay in the work.
- Conservator Qualifications: Contractor shall provide a professional conservator who must be approved by RHPO and GSA Contracting Officer prior to award of contract. The conservator shall have the following qualifications:
- Experience of at least five years in providing services of the kind indicated which has resulted in the successful installation of assemblies similar in material, design, and extent to that indicated for this project.
- Extensive repousse metalwork experience is an absolute requirement for this project. Common sheet metal work does not qualify as experience in this instance.
- The same conservator used for the repair of metalwork should be used to remove and re-install the metalwork.
- For conservation referral services, write or call the following: American Institute for Conservation of Historic and Artistic Works www.conservation-us.org This agency is listed for Contractor convenience ONLY. Any conservator chosen by the contractor must submit their qualifications for government approval.
- Use Only experienced riggers with at least three years successful experience to move all pieces from their existing positions to the truck, to the studio, and back again.
B. Pre-Installation Conference: Conduct conference at project site to review scope of project and ensure the understanding of the Scope of Work by all parties. Attendees shall include the RHPO, GSA Contracting Officer, contractor and conservator. The installer and fabricator may be in attendance as necessary.
1.04 DELIVERY, STORAGE, AND HANDLING
A. Packing and Shipping: Perform conservation work in such a manner that the safety of all ornamental metal components is assured during all loading and unloading operations, removal from existing locations, transportation to place of repair, repair itself, transportation back to building, reinstallation, and patination.
B. Storage and Protection:
- All conservation work on removed ornamental metal shall be performed in the conservator's studio. The studio shall comply with OSHA regulations regarding environmental precautions for the work necessary to repair and refurbish required pieces.
- Store all materials in clean, dry location, away from uncured concrete and masonry. Cover with waterproof paper, tarpaulin or polyethylene sheeting in a manner that permits air circulation within covering.
- Handle ornamental metalwork on site to a minimum. Exercise care to avoid damaging metal finishes.
1.05 PROJECT/SITE CONDITIONS
A. Field Measurements: Take field measurements prior to preparation of shop drawings and fabrication, where possible, to ensure proper fitting of ornamental metalwork. Do not delay job progress. Allow for adjustments and fitting where taking of field measurements before fabrication might delay Work.
- General: Provide ornamental copper metalwork composed of the forms and types which comply with project requirements and match as closely as possible existing copper metalwork.
- New and repaired work is to be free from surface blemishes where exposed to view in the finished unit. Exposed-to-view surfaces exhibiting pitting, seam marks, roller marks, "oil canning," stains, discolorations or other imperfections on finished units are not acceptable.
B. Miscellaneous Materials:
- Welding Electrodes and Filler Metal: Type and alloy of filler metal and electrodes as recommended by producer of metal to be welded, complying with applicable the American Welder's Society (AWS) specifications, and as required for color match, strength and compatibility in the fabricated items. Conservator shall supply the Government with manufacturer's certification that material recommended is compatible with metal on which use is recommended.
- Fasteners: Of same basic metal and alloy as fastened metal, unless otherwise indicated. Do not use metals which are corrosive or incompatible with metals joined.
- Provide concealed fasteners similar to existing fasteners for interconnection of ornamental metalwork components and for their attachment to other work, except where otherwise indicated.
- Provide exposed fasteners for interconnection of ornamental metalwork components and for their attachment to other work only where exposed fasteners are unavoidable.
- Anchors and Inserts: Provide anchors of type, size and material required for type of loading and installation condition shown, as recommended by manufacturer, unless otherwise indicated. Use nonferrous metal or hot-dipped galvanized anchors and inserts for exterior locations and elsewhere as required for corrosion resistance. Use toothed steel or expansion bolt devices for drilled-in-place anchors.
- General: Prepare, pretreat, and apply patina and protective acrylic lacquer and/or wax coating to all raw copper that results from repair of metalwork copper. The patination color shall match existing as closely as possible. Patina color shall be as approved by RHPO. Comply with patina and coating manufacturer's instructions.
- Copper: Finishes shall conform with the system established by the Copper Development Association for designating copper alloy finish systems. Protective finishes shall be as directed by project conservator.
A. Shop Assembly:
- Form ornamental copper metalwork to required shapes and sizes, with true curves, lines and angles using repousse technique similar to original repousse technique. Provide components in sizes and profiles indicated, but not less than required to comply with requirements indicated by Secretary of the Interior's "Standards for Rehabilitation and Guidelines for Rehabilitating Historic Buildings."
- Allow for thermal movement resulting from the following maximum change (range) in ambient temperature, in the design, fabrication, and installation of installed metal assemblies to prevent buckling, opening up of joints and overstressing of welds and fasteners. Base design calculations on actual surface temperatures of metals due to both solar heat gain and night time sky heat loss. Range of temperature change shall be from 10 degrees F to 180 degrees F.
- Provide necessary lugs and brackets for assembly of units. Use concealed fasteners wherever possible.
- Comply with AWS for recommended practices in shop welding. Provide welds, if needed, behind finished surfaces without distortion or discoloration of exposed side. Clean exposed welded joints of all welding flux, and dress on all exposed and contact surfaces.
- Mill joints to a tight, hairline fit. Cope or miter corner joints. Form joints exposed to weather to exclude water penetration.
- Provide bronze bracket castings that are sound and free of warp or defects which would impair strength and appearance.
- Finish exposed surfaces to smooth, sharp, well-defined lines and arises.
- Pre-assemble items in shop to greatest extent possible to minimize splicing and assembly. Disassemble units only as necessary for shipping and handling limitations. Clearly mark units for re-assembly and coordinated installation.
B. Performance Requirements: Structural Performance of Repaired Statuary Assemblies: Design, engineer, remove, fabricate, repair and install ornamental metalwork to comply with requirements of this specification for structural performance.
A. Surface Preparation:
- Coordinate and furnish anchorages and setting drawings, diagrams, templates, instructions and directions for installation of items having integral anchors which are to be embedded in concrete or masonry construction. Coordinate delivery of such items to the project site.
- Preparation for Patina: Clean metal surfaces of dirt, grease, black atmospheric pollution, and corrosion products, including any material that would prohibit adherence of patina.
3.02 ERECTION, INSTALLATION, APPLICATION
A. De-Installation: De-installation of all ornamental metalwork is the responsibility of the conservator and shall be performed according to the conservator's instructions and under the conservator's supervision.
B. Repair and Restoration:
- All repair and restoration work of this contract shall be performed in accordance with the Secretary of the Interior's "Standards for Rehabilitation and Guidelines for Rehabilitating Historic Buildings" (see 01091-04-S through 01091-19-S for guidance).
- Repair to sound condition all ornamental metalwork and seams using RHPO approved fabrication and repair techniques.
C. Installation, General:
- Provide anchorage devices and fasteners where necessary for securing ornamental metalwork and other items to in-place construction including, threaded fasteners for concrete and masonry inserts, toggle bolts, through-bolts, lag bolts, wood screws and other connectors as required.
- Contractor shall provide for conservator to perform cutting, drilling and fitting required for installation of ornamental metalwork, and to reinstall items accurately in same location and position, alignment and elevation, from which removed. These items shall be plumb, level and true, measured from established lines and levels. Provide temporary bracing or anchors for items which are to be built into concrete, masonry or similar construction.
- Fit exposed connections accurately together to form tight, hairline joints or, where indicated, with uniform reveals and spaces for sealants and joint fillers. Where cutting, welding and grinding are required for proper shop fitting and jointing of ornamental metal items, restore finishes to eliminate any evidence of such corrective work.
- Do not cut or abrade finishes which cannot be completely restored in the field. Return items with such finishes to the shop for required alterations, followed by complete refinishing or provide new units as required.
- Install concealed gaskets, joint fillers, and flashings as the work progresses, so as to make work weathertight.
- Restore protective coverings which have been damaged during shipment or installation of the work. Remove protective coverings only when there is no possibility of damage from other work yet to be performed at the same location.
- Retain protective coverings intact and remove simultaneously from similarly finished items to preclude nonuniform oxidation and discoloration.
- Field Welding: Comply with applicable AWS specification for procedures of manual shielded metal-arc welding, for appearance and quality of welds made, and for methods used in correcting welding work.
- Perform all other functions required to effect complete conservation and repair of all ornamental metalwork.
A. Touch-Up Patination: Conservator shall perform touch-up patination and coating with acrylic sealer and/or wax at all areas of ornamental metalwork that are not patinated to the satisfaction of the RHPO.
A. Protect finishes of ornamental metalwork from damage during construction period by use of temporary protective coverings approved by ornamental metalwork conservator. Remove protective covering at time of Substantial Completion.
B. Restore finishes damaged during installation and construction period so that no evidence remains of correction work. Return items which cannot be refinished in the field to the shop. Make required alterations and refinish entire unit, or provide new units as required.
- Margot Gayle, David W. Look, John Waite. Metals in America's Historic Buildings. Washington, DC: National Park Service, 1992.
- L. William Zahner. Architectural Metals. New York: John Wiley & Sons, Inc., 1995.