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 includes guidance on making small temporary repairs to roof flashing by patching small holes with sheetmetal. See also 07631-03-R for additional guidance on patching sheetmetal. For more extensive flashing repairs, see 07620-02-R.
B. Flashing is an integral part of a roofing system and protects against water infiltration at roof hips and valleys; penetrations such as chimneys; where roofing meets a vertical surface such as a parapet or at a porch roof; or at drip edges.
C. Copper, with copper nails, galvanized sheet metal with hot-dipped galvanized nails, or terne-coated stainless steel with stainless steel nails are the primary materials used for flashing.
Caution: The different metals should not be mixed. Rainwater run-off from copper flashing will corrode both galvanized sheet metal and stainless steel through galvanic action. Great care should be taken to use a flashing material compatible wtih the rest of the roof system.
D. Safety Precautions:
- Wear rubber-soled shoes that have non-slip or grid type tread (preferably high top sneakers for good ankle support. Avoid wearing loose clothing.
- Wear a safety belt or harness secured to a substantial chimney or to a window on the opposite side of the building. Leave only enough slack to work comfortably in one area, and adjust the slack as work proceeds on other sections of the roof.
- Be sure the roof is clear of debris and water.
- Do not work on wet or snow covered roofs, or on a brittle roof surface. Work on cleated walkboards.
- On steep roofs:
- Secure chicken ladders or cleats at the top for adequate footing.
- Safety lines should be tied and secured with manila rope.
- Carry a limited amount of materials so that balance and footing are not impaired.
E. 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 before performing this procedure and should be followed, when applicable, along with recommendations from the Regional Historic Preservation Officer (RHPO) or designated representative.
1.02 SYSTEM DESCRIPTION
A. Flashing is performing as it was intended when there are no cracks, splits or torn areas. It should not show any signs of corrosion. Where flashing meets a vertical surface, all cap flashing should be secure and the flashing itself should be soundly anchored.
A. Check flashings as a part of the annual roof inspection (preferably in late autumn). Repair defects immediately because flashing is a critical part of the roof fabric. Small leaks in the flashing which are neglected may lead to major faults in the roof system. See also Section 3.01 Examination below.
A. Flashing material: 16 oz. or 20 oz. sheet copper; lead-coated copper; 26 gauge galvanized steel. Metal should match remaining metals on the roof.
B. Flashing cement or roofing compound
C. Clean, soft cloths
D. See also materials/manufacturers listed in Part 2 of 07631-03-R.
A. Safety belt or harness; protective gloves and gear.
B. Chicken ladder; ladders and scaffolding.
C. Straight snips for cutting straight or slightly curved lines in sheet metal 24 gauge or lighter.
D. Stiff bristle brushes
E. See also equipment listed in Part 2 of 07631-03-R.
A. Flashing is usually a weak part of the roofing system and, therefore, should be inspected regularly for damage or deterioration.
- Outside, inspect flashing for splits, holes or corrosion.
- Inside, inspect the underside of the roof deck for evidence such as water stains or damp wood; inspect the ceiling and walls around fireplaces and chimney flues for stained or spalling plaster or wallpaper, or peeling paint.
- Look for daubs of roofing cement on the flashing—this is an indication of previous leaks. This type
of repair is not recommended and may not have completely stopped the leak.
- Look for uncaulked openings at the tops of flashing where water may enter.
A. Surface Preparation: Select sheetmetal type to be used making sure it is compatible with the remaining flashing on the roof.
3.03 EXECUTION, INSTALLATION, APPLICATION
A. See 07631-03-R for three different methods of patching small holes in sheetmetal. The methods described in that procedure are recommended for patching metal gutters, but may also be used for making temporary patches to flashing. For guidance on making more extensive repairs to flashing, see 07620-02-R.