Section07620 ShtmtlFlashing Trim.doc

Solicitation No.AG-95CV-S-09-0020 Recovery – Replace or Repair/Resurface Roofs, Main Bldg

(N.Wing), WAB, Service Bldg, WRRC, Albany, CA

SECTION 07620 – SHEET METAL FLASHING AND TRIM (Section applies only to WAB (Labs) roof)

PART 1 GENERAL

1.1

RELATED DOCUMENTS

A.

General provisions of the Contract, including General and Supplementary Conditions and Division 1 Specification Sections, apply to this Section.

B.

“Supplemental Information – WAB (Labs) Roof” applies to this Section.

1.2

SUMMARY

A.

This Section includes the following:

1.

Sheet metal flashing and trim.

B.

Related Sections include the following:

1.

Section 06105 for wood nailers, curbs, and blocking.

2.

Section 07540 for installing sheet metal flashing and trim integral with roofing.

1.3

PERFORMANCE REQUIREMENTS

A.

General: Install sheet metal flashing to withstand wind loads, structural movement, thermally induced movement, and exposure to weather without failing, rattling, leaking, and fastener disengagement.

B.

Fabricate and install flashings capable of resisting applicable forces, per recommendations in FMG Loss Prevention Data Sheet 1-49.

C.

Thermal Movements: Provide sheet metal flashing and trim that allow for thermal movements resulting from the following maximum change (range) in ambient and surface temperatures by preventing buckling, opening of joints, hole elongation, overstressing of components, failure of joint sealants, failure of connections, and other detrimental effects.

1.

Temperature Change (Range) 120 deg, ambient; material surfaces.

D.

Water Infiltration: Provide sheet metal flashing and trim that do not allow water infiltration to building interior.

1.4

SUBMITTALS

A.

Product Data: Provide for each type of product indicated. Include construction details, material descriptions, dimensions of individual components and profiles, and finishes.

B.

Samples for Initial Selection: For each type of sheet metal flashing and trim with factory-applied color finishes.

C.

Samples for Verification: For each type of exposed finish required, prepared on Samples of size indicated below:

1.

Sheet Metal Flashing: 12 inches long. Include fasteners, clips, closures, and other attachments.

2.

Trim: 12 inches long. Include fasteners and other exposed accessories.

3.

Accessories: Full-size Sample.

1.5

QUALITY ASSURANCE

A.

Sheet Metal Flashing and Trim Standard: Comply with SMACNA's "Architectural Sheet Metal Manual." Conform to dimensions and profiles shown unless more stringent requirements are indicated.

B.

Pre-Installation Conference: Conduct conference at Project site:

1.

Meet with Contracting Officer’s Representative (COR), flashing Installer, and installers whose work interfaces with or affects sheet metal flashing and trim, including installers of roofing materials and roof accessories.

2.

Review methods and procedures related to sheet metal flashing and trim.

3.

Examine substrate conditions for compliance with requirements, including flatness and attachment to structural members.

4.

Document proceedings, including corrective measures and actions required, and furnish 3ea. copies of record to COR.

1.6

DELIVERY, STORAGE, AND HANDLING

A.

Deliver sheet metal flashing materials and fabrications undamaged. Protect sheet metal flashing and trim materials and fabrications during transportation and handling.

B.

Unload, store, and install sheet metal flashing materials and fabrications in a manner to prevent bending, warping, twisting, and surface damage.

C.

Stack materials on platforms or pallets, covered with suitable weathertight and ventilated covering. Do not store sheet metal flashing and trim materials in contact with other materials that might cause staining, denting, or other surface damage.

1.7

COORDINATION

A.

Coordinate installation of sheet metal flashing and trim with interfacing and adjoining construction to provide a leakproof, secure, and noncorrosive installation.

PART 2 - PRODUCTS

2.1

MANUFACTURERS

A.

In other Part 2 articles where titles below introduce lists, the following requirements apply to product selection:

1.

Available Products: Subject to compliance with requirements, products that may be incorporated into the Work include, but are not limited to, products specified.

2.2

SHEET METALS

A.

Galvanized steel Sheet: ASTM A 526, twenty four (24) gauge GSM.

1.

Finish: Standard.

B.

Lead Sheet: ASTM B 749, Type L51121, copper-bearing lead sheet.

2.3

UNDERLAYMENT MATERIALS

A.

Peel-n-stick Sheet: Self adhering SBS modified bitumen sheet. Product meets ASTM D 6163, Type 1, Grade S; Tremco or Government approved equal.

2.4

MISCELLANEOUS MATERIALS

A.

General: Provide materials and types of fasteners, solder, welding rods, protective coatings, separators, sealants, and other miscellaneous items as required for complete sheet metal flashing and trim installation.

B.

Fasteners: Wood screws, annular threaded nails, self-tapping screws, self-locking rivets and bolts, and other suitable fasteners designed to withstand design loads.

1.

Exposed Fasteners: Heads matching color of sheet metal by means of plastic caps or factory-applied coating.

2.

Fasteners for Flashing and Trim: Blind fasteners or self-drilling screws, gasketed, with hex washer head.

3.

Blind Fasteners: High-strength aluminum or stainless-steel rivets.

C.

Solder for Stainless Steel: ASTM B 32, Grade Sn60, with acid flux of type recommended by stainless-steel sheet manufacturer.

D.

Solder for Lead: ASTM B 32, Grade Sn50, 50 percent tin and 50 percent lead.

E.

Burning Rod for Lead: Same composition as lead sheet.

F.

Sealing Tape: Pressure-sensitive, 100 percent solids, polyisobutylene compound sealing tape with release-paper backing. Provide permanently elastic, non-sag, nontoxic, non-staining tape.

G.

Elastomeric Sealant: ASTM C 920, elastomeric polyurethane polymer sealant; of type, grade, class, and use classifications required to seal joints in sheet metal flashing and trim and remain watertight.

H.

Butyl Sealant: ASTM C 1311, single-component, solvent-release butyl rubber sealant, polyisobutylene plasticized, heavy bodied for hooked-type expansion joints with limited movement.

I.

Epoxy Seam Sealer: Two-part, noncorrosive, aluminum seam-cementing compound, recommended by aluminum manufacturer for exterior nonmoving joints, including riveted joints.

2.5

FABRICATION, GENERAL

A.

General: Custom fabricate sheet metal flashing and trim to comply with recommendations in SMACNA's "Architectural Sheet Metal Manual" that apply to design, dimensions, metal, and other characteristics of item indicated. Shop fabricate items where practicable. Obtain field measurements for accurate fit before shop fabrication.

B.

Fabricate sheet metal flashing and trim in thickness or weight needed to comply with performance requirements, but not less than that specified for each application and metal.

C.

Fabricate sheet metal flashing and trim without excessive oil canning, buckling, and tool marks and true to line and levels indicated, with exposed edges folded back to form hems.

1.

Seams for Other Than Aluminum: Fabricate nonmoving seams in accessories with flat-lock seams. Tin edges to be seamed, form seams, and solder.

D.

Sealed Joints: Form nonexpansion but movable joints in metal to accommodate elastomeric sealant to comply with SMACNA recommendations.

E.

Expansion Provisions: Where lapped or bayonet-type expansion provisions in the Work cannot be used, form expansion joints of intermeshing hooked flanges, not less than 1 inch deep, filled with elastomeric sealant concealed within joints.

F.

Conceal fasteners and expansion provisions where possible on exposed-to-view sheet metal flashing and trim, unless otherwise indicated.

G.

Fabricate cleats and attachment devices from same material as accessory being anchored or from compatible, noncorrosive metal.

1.

Thickness: As recommended by SMACNA's "Architectural Sheet Metal Manual" for application but not less than thickness of metal being secured.

2.6

LOW-SLOPE ROOF SHEET METAL FABRICATIONS

A.

Skirt flashings: Fabricate from the following material:

1.

Galvanized Steel: ASTM A 526, minimum twenty four (24) gauge thick.

B.

Counterflashing: Fabricate from the following material:

1.

Galvanized Steel: ASTM A 526, minimum twenty four (24) gauge thick.

C.

Roof-Penetration Flashing / drains: Fabricate from the following material:

1.

Lead: 4 lb / sq ft, hard tempered.

D. Gravelstop: Twenty four (24) gauge TPA coated metal

2.7

FINISHES

A.

Comply with NAAMM's "Metal Finishes Manual for Architectural and Metal Products" for recommendations for applying and designating finishes.

B.

Protect mechanical and painted finishes on exposed surfaces from damage by applying a strippable, temporary protective covering before shipping.

C.

Appearance of Finished Work: Variations in appearance of abutting or adjacent pieces are acceptable if they are within one-half of the range of approved Samples. Noticeable variations in the same piece are not acceptable. Variations in appearance of other components are acceptable if they are within the range of approved Samples and are assembled or installed to minimize contrast.

PART 3 - EXECUTION

3.1

EXAMINATION

A.

Examine substrates, areas, and conditions, with Installer present, to verify actual locations, dimensions and other conditions affecting performance of work.

1.

Verify that substrate is sound, dry, smooth, clean, sloped for drainage, and securely anchored.

2.

Proceed with installation only after unsatisfactory conditions have been corrected.

3.2

INSTALLATION, GENERAL

A.

General: Anchor sheet metal flashing and trim and other components of the Work securely in place, with provisions for thermal and structural movement. Use fasteners, solder, welding rods, protective coatings, separators, sealants, and other miscellaneous items as required to complete sheet metal flashing and trim system.

1.

Torch cutting of sheet metal flashing and trim is not permitted.

B.

Metal Protection: Where dissimilar metals will contact each other or corrosive substrates, protect against galvanic action by painting contact surfaces with bituminous coating or by other permanent separation as recommended by fabricator or manufacturers of dissimilar metals.

1.

Adhere TF flashing tape to sheet metal flashing and trim where flashing and trim will contact wood, ferrous metal, or cementitious construction.

2.

Underlayment: Where installing metal flashing directly on cementitious or wood substrates, install a course of peel-n-stick and extend down face of wall a minimum of six (6) inches 3.

Bed flanges in thick coat of asphalt roofing cement where required for waterproof performance.

C.

Install exposed sheet metal flashing and trim without excessive oil canning, buckling, and tool marks.

D.

Install sheet metal flashing and trim true to line and levels indicated. Provide uniform, neat seams with minimum exposure of solder, welds, and butyl sealant.

E.

Install sheet metal flashing and trim to fit substrates and to result in watertight performance. Verify shapes and dimensions of surfaces to be covered before fabricating sheet metal.

F.

Fasteners: Use fasteners of sizes that will penetrate substrate not less than 1 ¼ inches for nails and not less than 3/4 inch for wood screws with washers.

1.

Galvanized or Prepainted, Metallic-Coated Steel: Use stainless-steel fasteners.

2.

Aluminum: Use aluminum or stainless-steel fasteners.

3.

Copper: Use copper or stainless-steel fasteners.

4.

Stainless Steel: Use stainless-steel fasteners.

G.

Seal joints with butyl sealant as required for watertight construction.

1.

Where sealant-filled joints are used, embed hooked flanges of joint members not less than 1 inch into sealant. Form joints to completely conceal sealant. When ambient temperature at time of installation is moderate, between 40 and 70 degrees F, set joint members for 50 percent movement either way. Adjust setting proportionately for installation at higher ambient temperatures. Do not install sealant-type joints at temperatures below 40 degrees F.

H.

Soldered Joints: Clean surfaces to be soldered, removing oils and foreign matter. Pre-tin edges of sheets to be soldered to a width of 1 ½ inches except where pre-tinned surface would show in finished Work.

1.

Pre-tinning is not required for lead.

2.

Stainless-Steel Soldering: Pre-tin edges of uncoated sheets to be soldered using solder recommended for stainless steel and phosphoric acid flux. Promptly wash off acid flux residue from metal after soldering.

3.

Where surfaces to be soldered are lead coated, do not tin edges, but wire brush lead coating before soldering.

4.

Lead-Coated Copper Soldering: Wire brush edges of sheets before soldering.

5.

Do not use open-flame torches for soldering. Heat surfaces to receive solder and flow solder into joints. Fill joints completely. Completely remove flux and spatter from exposed surfaces.

3.3

ROOF FLASHING INSTALLATION

A.

General: Install sheet metal roof flashing and trim to comply with performance requirements and SMACNA's "Architectural Sheet Metal Manual." Provide concealed fasteners where possible, set units true to line, and level. Install work with laps, joints, and seams that will be permanently watertight.

B.

Pipe Counterflashing: Install counterflashing umbrella with close-fitting collar with top edge flared for butyl sealant, extending a minimum of 4 inches over base flashing. Install stainless-steel draw band and tighten.

C.

Counterflashing: Coordinate installation of counterflashing with installation of base flashing. Insert counterflashing in reglets or receivers and fit tightly to base flashing. Extend counterflashing 4 inches over base flashing. Lap counterflashing joints a minimum of 4 inches and bed with butyl sealant.

D.

Roof-Penetration Flashing: Coordinate installation of roof-penetration flashing with installation of roofing and other items penetrating roof. Install flashing as follows:

1.

Turn lead flashing down inside vent piping, being careful not to block vent piping with flashing.

2.

Seal with elastomeric sealant and clamp flashing to pipes penetrating roof except for lead flashing on vent piping.

3.4

CLEANING AND PROTECTION

A.

Clean exposed metal surfaces of substances that interfere with uniform oxidation and weathering.

B.

Clean and neutralize flux materials. Clean off excess solder and sealants.

C.

Remove temporary protective coverings and strippable films as sheet metal flashing and trim are installed. On completion of installation, clean finished surfaces, including removing unused fasteners, metal filings, pop rivet stems, and pieces of flashing. Maintain in a clean condition during construction.

D.

Replace sheet metal flashing and trim that have been damaged or that have deteriorated beyond successful repair by finish touchup or similar minor repair procedures.

END OF SECTION 07620

SHEET METAL FLASHING AND TRIM

07620 - 1 (Section applies only to WAB (Labs) roof)