Section_J_-_Att_No__002_SOW.pdf

Re-Roof Fort Cronkhite Building 1067

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PART 1 – GENERAL

1.01 WORK INCLUDED

A. Remove (with the intent of preserving the existing 1x sheathing) and legally recycle all existing composition shingle roofing, asphalt underlayment, flashings and all other associated debris generated by this activity.

Note; with prior approval from COR/PM, mutually agreed upon flashings, roof jacks or other accessories may be suitable for re-installation. Submit list for consideration with proposal.

B. Selectively remove, legally dispose of or recycle deteriorated or structurally unstable roof sheathing; extent shall be as determined by COR/PM after inspection of substrate once roofing has been removed.

Contractor to give 48 hours (2 working days) prior notice to COR/PM to request post removal inspection of substrate.

C. Roofing Assembly

1. Provide and install new 7/16 OSB sheathing across entire main roof plane of building including overhangs at gabled ends.

2. Provide & install new synthetic underlayment, flashings, roof jacks, vents and accessories. Paint siding repairs to match existing. Back prime any new siding and/or trim.

3. Install new roof system according to all manufacturer’s installation instructions;

includes “Six-Nail Fastening Pattern” and “Mansfard or Steep Slope Pattern” over a manufacturer approved contractor supplied synthetic underlayment.

4. Shingles shall be Owens Corning Supreme shingles. Color shall be Spanish Red. All shingles must be from the same lot. Bundles from multiple lots will be rejected.

1.03 BACKGROUND

A. Buildings FOCR T-1067

1. Age: Circa 1940-1941

2. Historic Status: The building is a contributing structure in the Forts Baker, Barry, and

Cronkhite National Register Historic District. During the work, Contractor shall exercise

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great care to protect the buildings and surrounding area from damage. Contractor to repair to the satisfaction of the COR/PM any damages caused by contractor’s own forces or forces under the contractor’s direction at no expense to the NPS.

3. Roof structure: The existing roofing is 22 years old. The roof framing should be evaluated prior to undertaking the work of this contract. Care should be exercised during the work to avoid overloading the existing roof rafters and sheathing.

4. Hazardous Materials: Roofing materials have not been checked for asbestos content. It is assumed contractor will comply with all current regulations regarding the treatment of hazardous materials during the performance of this contract.

B. Additional Requirements, Clarifications, and Information

1. The tasks contained in this project are primarily related to roofing rehabilitation. It shall be noted by the contractor that these tasks are located in a contributing national historic landmark area and include selective demolition around sensitive building elements, landscapes, roadways, and paths.

2. This is a high-profile project with public exposure located in the Golden Gate National Recreation Area. In addition to the requirements contained in the plans and specifications, National Park Service expects and will demand a commensurate superior level of quality, standard of care, and attention to detail during the performance of this contract. Poor housekeeping and/or uncooperative responses to CO or COR directives may result in withholding of progress payments.

3. The Contractor is expected to have comprehensive equivalent project experience and demonstrate this experience in the proposal by submitting to the CO qualifications attesting to the proposer’s ability to perform the required tasks.

4. Included in the proposal the Contractor shall submit to the CO any requirements which the proposer expects the NPS to provide within the GGNRA, such as roadway capacities, clearances to existing structures and landscapes, or any other necessary accommodations not currently present in the Park which would prevent the contractor from performing the work under this contract. No vehicles, trucks, or heavy equipment will be allowed off the pavement to access the project without pre-approval of the COR. There is no adequate power or water available on site for the contractors use; provide description of alternative supplies for NPS approval with proposal.

5. The majority of utilities within the Park are owned by NPS. As such, very few utilities will actually be marked by USA. It is the Contractor’s responsibility to field locate, verify and mark all utilities within the project area. Contractor shall be responsible for locating and preventing damage to utilities. If damage occurs, repair utility at no additional expense to the Government.

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6. The Contractor shall submit with proposal a general schedule and sequence of events. The scheduled shall describing dates, durations, and resources used for the project. Project Completion Date to be 60 days after NTP.

7. Point of Contact: NPS Project Manager/COR Tommy Daigle.

Thomas_daigle@nps.gov 415-415-3076

1.04 REFERENCES

A. Sheet Metal and Air Conditioning Contractors National Association (SMACNA):

Architectural Sheet Metal Manual

B. National Roofing Contractors Association (NRCA)

C. ASTM Reference Standards (ASTM)

D. 2015 IBC

1.05 SUBMITTALS

A. Submit three (3) copies of the following for NPS review and acceptance:

1. Product Data: Manufacture’s literature.

a) All fasteners used for flashings, sheathing, siding repairs, underlayment felt, OSB installation, and roofing shingles.

b) Flashings, Roof Jacks, Vent Caps, Flue Caps

c) Sealants

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1.06 WARRANTY

A. Provide for correcting failure of roofing system to resist penetration of water. Including material and labor at no expense to the Government. Warranty period: Two years from date of substantial completion.

1.07 Definition of Contract Line Items

CLIN 1-Modilization/De-mobilization. Includes all costs associated with mobilization and de-mobilizations.

CLIN 2-Re-Roof. Includes materials and labor associated with the removal of existing shingles, decking overlay, and install of roofing system. Also includes recycling of shingles and removal of any associated debris.

PART 2 – PRODUCTS

2.01 ROOFING MATERIALS

A. New Shingles: fiberglass reinforced asphalt composition roofing shingles;

conforming to ASTM D3462 and ASTM D3018, Type 1; shingles bearing UL Class A fire and “Wind Resistant” labels.

1. Manufacturers: Owens Corning, 3 tab shingles Supreme series, color to be “Spanish Red”.

2. Exposure: approximately 6-inches.

3. Accessories: ridge and hip shingles shall be cut out of 3-tab shingles. Starter shingles are required.

4. Color: Spanish Red

B. Roofing synthetic underlayment: As required for manufacturer’s warranty. Synthetic underlayment shall have non-woven surface construction.

C. Shingle Nails: Standard barbed shank round wire shingle type of hot dipped zinc coated steel minimum 3/8” head diameter, 11 or 12 gages; minimum 1-1/4” long. Note: use caution at exposed overhangs, do not penetrate through sheathing with fasteners. Pneumatically or otherwise installed Electro Galvanized (AKA EG) nails are prohibited.

D. Plastic Cement: Cutback asphaltic type; free of toxic solvents and free of asbestos. Provide material capable of setting within 24 hours at temperatures of approximately 75 degrees F and 50 percent relative humidity.

E. Lap Cement: Fibrated cutback asphaltic type, for use an adhesive in cold application of asphalt roofings of underlayments; free of toxic solvents and free of asbestos.

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F. OSB Sheathing: 7/16”

G. Plumbing Jacks, Flashings, hoods, collars, Vent Caps; 20 oz. copper.

2.02 FLASHING FABRICATION

A. Flashing: Copper Sheet ASTM B 370, 20 oz. minimum, temper as required for forming.

B. Form sections square, true and accurate to size, free from distortion and other defects detrimental to appearance or performance.

C. Fabricate sheet metal in accordance with SMACNA Architectural Sheet Metal Manual.

D. Form sections in maximum, 10’-0” lengths; make allowance for expansion at joints. Form joints between sections according to SMACNA details.

PART 3 – EXECUTION

3.01 PREPARATION

A. Inspect existing rooftop with COR/PM and replace damaged and deteriorated wood sheathing materials exposed during removal of roofing materials as directed. Extent shall be as determined by COR/PM after inspection of substrate once roofing has been removed.

Contractor to give 48 hours (2 working days) prior notice to COR/PM to request inspection.

B. Install plywood underlayment across entire roof plane. Remove (E) roofing and install (N) 7/16” OSB sheathing over existing 1x sheathing. Install plywood in full sheets as much as practical with long edge perpendicular to rafters in lengths spanning a minimum of 4 rafters, gap all joints as per manufacturer and stagger 32”-inches minimum. Where full panels are cut, minimum panel size width shall be 24”-inches and 32”-inches in length. Edges of plywood sheathing should be located on center of individual sheathing boards, fastened with Helical Threaded nails. Nails shall have .148 –inch min. diameter and 3” minimum length (10d nails). Nails typ. placed at 4” o.c. at panel edges 8” o.c. for field nailing. Nails with clipped heads will not be allowed. Contractor shall snap chalk lines at rafter centers to confirm nails are driven into rafters.

2) Exposed eaves and overhangs; plywood shall be attached using Stainless Steel 8d nails, 4” on center at the perimeter edges and 6” in the field. DO NOT OVER DRIVE. Nails shall not penetrate the underside of the existing sheathing and be exposed from below. Contractor shall be responsible for replacement of sheathing at their own expense to the satisfaction of the COR/PM should any penetrations occur.

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Notify COR/PM prior to installing roof underlayment for site inspection and acceptance of plywood installation. Allow for 48 hours advance notification.

C. Coordinate installation of roofing with installation of new copper roof jacks, vent and termination caps, and wall flashings. Perimeter of roof to receive copper drip edge metal under roofing to cover plywood edge and edge of original sheathing. Install roof to wall flashing to match existing.

Notify COR/PM prior to installing roof cover for site inspection and acceptance of flashings, jacks and any other accessories. Allow for 48 hours advance notification.

3.02 FLASHING INSTALLATION

A. Install metal flashing and sheet metal in accordance with SMACNA Architectural Sheet Metal

Manual, NRCA Roofing and Waterproofing Manual & Copper Development Association. In the event of conflicting information, strictest interpretation prevails.

B. Exercise care when cutting materials on site, to ensure cuttings do not remain on finished surfaces.

C. Install sealants only as insurance where proper lapping is not possible and only as approved in advance by COR/PM.

D. Use only copper or marine grade stainless steel fasteners for attachment.

E. Lock seams and end joints; fit flashing tight in place; make corners square, surfaces true and straight in planes, and lines accurate to profiles. Hem exposed edges and drip legs.

F. Under-break roof to wall metal flashing so flashing apron is installed tight to shingles.

3.03 ROOFING ASSEMBLY INSTALLATION

A. Install one (1) layer of new synthetic felt underlayment horizontally; lap underlayment minimum 2” and lap edges minimum 6”; stagger layers minimum 12” and stagger end laps.

B. Lay new shingles in accordance with manufacturer’s recommendations for six-nail pattern and mansard roofs to meet manufacturer’s specified maximum fire and wind requirements.

1. Coursing Pattern: Match existing. Install shingles in horizontal lifts (NOT in vertical lifts);

provide a continuous color tone across the roof plane.

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2. Conform with requirements of applicable codes.

3. Nail shingles: do not staple. Install 6 nails per 3-tab shingle using 1.25-inch #12 hot dipped galvanized nails with 3/8-inch diameter head. Do not overdrive nails. Use shorter ring shank fasteners at exposed eaves that do not have plywood to avoid fastener breakthrough.

4. Adhesive at boundaries: at rakes and eves, secure shingles with hand tabbing of asphalt roof cement.

5. Temperature during roofing installation: between 40-degrees F and 85-degrees F.

6. During installation days with heavy wind or temperatures below 65-degrees, apply heat gun to integral adhesive on shingle tab to assure firm set.

7. Apply lap cement to bottom corners of each exposed shingle to assure firm set with wind uplift.

C. Conceal fastenings in completed installation of roofing.

1. Do not penetrate underside of any exposed overhang or eave with any fasteners.

Contractor responsible for replacement of sheathing at their own expense to the satisfaction of the COR/PM should any penetrations occur.

D. Flash and seal items projecting through or mounted on roofing with COR/PM approved sealant.

E. Provide weathertight completed roofing installation.

3.04 PROJECT CLOSE-OUT

A. Clean up: Remove all and any other surplus material, rubbish and debris from the site that accumulated during the construction work. Leave the entire area neat, clean and acceptable to the PM/COR.

END OF SECTION