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Historic Preservation - Technical Procedures

Spectitle:

Repairing Small Holes In Roof Flashing

Procedure code:

0762003R

Source:

Ohj - Feb. 1981

Division:

Thermal And Moisture Protection

Section:

Sheet Metal Flashing And Trim

Last Modified:

02/24/2012

Details:

Repairing Small Holes In Roof Flashing



REPAIRING SMALL HOLES IN ROOF FLASHING


PART 1---GENERAL

1.01 SUMMARY

    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 WITH THE REST OF THE ROOF
         SYSTEM.

    D.   Safety Precautions:

         1.   Wear rubber-soled shoes that have non-slip or grid
              type tread (preferably high top sneakers for good
              ankle support.  Avoid wearing loose clothing.

         2.   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.

         3.   Be sure the roof is clear of debris and water.

         4.   Do not work on wet or snow covered roofs, or on a
              brittle roof surface.  Work on cleated walkboards.

         5.   On steep roofs:

              a.   Secure chicken ladders or cleats at the top
                   for adequate footing.

              b.   Safety lines should be tied and secured with
                   manila rope.

              c.   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:

         1.   Safety Precautions

         2.   Historic Structures Precautions

         3.   Submittals

         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 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.

1.03 MAINTENANCE

    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.


PART 2---PRODUCTS

2.01 MATERIALS

    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.

2.02 EQUIPMENT

    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.


PART 3---EXECUTION

3.01 EXAMINATION

    A.   Flashing is usually a weak part of the roofing system
         and, therefore, should be inspected regularly for damage
         or deterioration.

         1.   Outside, inspect flashing for splits, holes or
              corrosion.

         2.   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.

         3.   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.

         4.   Look for uncaulked openings at the tops of flashing
              where water may enter.

3.02 PREPARATION

    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.
   
                             END OF SECTION