Attachment_1__SOW__Gambrill_House_(06-25-2024).pdf

Attachment 1

STATEMENT OF WORK

06/25/2024

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1. BACKGROUND AND OBJECTIVES

The c. 1872 Gambrill House, located on Monocacy National Battlefield, is a Second Empire mansion that is home of the Historic Preservation Training Center leadership, training and admin teams. The scope of this project is to repair and replace deteriorated components of the front/north porch, side/east porch, the rear/west porch and the third floor, front/north balcony. The three porches all exhibit the ornate architectural elements of the Second Empire architectural style that was popular in the late 19th Century. Over the last 150 years there have been various repair campaigns to maintain and repair the porches. The goal of this project is to repair deteriorated elements while preserving extant historic /original architectural and structural materials.

2. STATEMENT OF WORK

Independently, and not as an agent of the Government, the Contractor shall provide all labor, materials, equipment and necessary for the repair and preservation of the front and side porches and balcony at the Gambrill House located at 4801A Urbana Pike, Frederick, MD.

All work shall be completed in accordance with the following:

Attachment 2, Specifications entitled, “Gambrill House Three Porches & Balcony Preservation:

Project Specifications”, consisting of 30 pages, Attachment 3, Informational Drawings entitled, “Gambrill House Historic American Buildings Survey (HABS) Drawings Excerpts”, 1991, consisting of 6 sheets.

The Contractor shall perform the following tasks:

1) MOBILIZATION - SITE ACCESS AND SCAFFOLDING

1) The contractor shall establish a secure perimeter, laydown area in location indicated. Project lay down area and approach to lay down area for staging and parking pictured below.

2) Contractor shall establish construction site perimeter with green plastic construction fencing and T-posts.

3) Contractor shall provide portable toilet and hand washing station for all personnel on site. Water is available at the site. Contractor may use power from the Gambrill House. Submit a site plan to National Park Service (NPS) for approval showing locations of portable toilets, construction trailer, staging areas, etc.

4) Contractor shall erect scaffolding and work platforms to access work from outside the building. No access will be provided from inside the Gambrill house. All scaffold and work platforms shall conform to industry practices and OSHA standards. Scaffolds and work platforms are to be securable to prevent access outside work hours.

2) THIRD FLOOR FRONT/NORTH BALCONY

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1) Contractor shall remove and replace (4) damaged/deteriorated, non-historic finials with new made from Sapele or Spanish Cedar, match size and shape and fastening methods.

2) Prepare (wash to remove mildew, caulk open joints, wet sand rough spots, spot prime bare wood, back prime new wood elements) and paint all painted wood surfaces (balustrade and balcony structure and brackets), per Attachment 2, specifications, entitled, “Gambrill House Three Porches & Balcony Preservation:

Project Specifications”, consisting of 30 pages.

3) FRONT/NORTH PORCH

1) Provide shoring for the Northeast corner support post before starting work on the roof or balustrade.

2) Disassemble and remove non-historic, balustrade from the porch roof (portions of the railing is pictured below). Remove extant flat seam metal roofing. Provide temporary weather protection after Roofing removal.

3) Inspect roof decking/sheathing and structural members. Remove center bay breast beam trim to expose structural beam within. Repair /replace damaged or deteriorated decking/sheathing (estimated to be 30% of the decking area). Repair / replace damaged or deteriorated structural members (estimated to be 30% of the roof area plus the center bay breast beam) and restore slope to the roof for positive drainage toward the built-in gutter. All new materials to be fastened per industry standards and practices.

4) Prepare roof deck for new flat seam metal roofing - removing all protruding nails and other rough elements from the new and extant decking.

5) Cover roof deck and built-in gutter with roof butyl underlayment that meets the following criteria:

• Heat resistant up to 300 degrees F

• Membrane forms watertight seal around roofing fasteners

• Membrane forms watertight overlaps without the need for additional treatment

• Plastic can be easily removed and disposed

6) Install new, fully soldered flat seam, architectural sheet copper coated with tin/zinc on both sides for roofing and built-in gutters. Copper sheets must meet the following criteria:

• Minimum thickness of 0.0005”

• Must have been tested, without failure to withstand accelerated weather elements and have been exposed to industrial, urban and rural environments.

• Product cannot contain lead

• Product may not weather into a red or orange color

• Product should have a satin micro-finish

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Copper flat seam roofing sheets shall be installed over red rosin paper “slip sheet”.

Flat seam panels shall be laid from the low end of the slope to the higher end.

Flat seam panels shall be formed from 18”X 24” sheets with 3/4” seams. Panels shall be attached to the roof deck with two copper or stainless-steel sheet metal cleats on each side and with two 1 ½” copper ring shank nails per cleat.

7) Remove deteriorated and damaged woodwork. Replace damaged components with

Spanish cedar or Sapele milled to match dimensions and profile. Including (4) four vents with screens and add screening to stair risers and ceiling prior to board install.

8) Replace lead coated copper gutter, built in box gutter, leaders, and downspouts.

9) Shore porch roof and remove support posts in locations of damaged porch decking (pictured below). Remove and replace deteriorated and damaged wooden elements. Replace damaged porch deck boards under post. Replace with Number 1 Douglas Fir in full length pieces match thickness and tongue and groove profiles of existing deck boards.

10) Repair and reinstall non-historic balustrade (estimated to be 30% of the components to be replaced).

11) Prepare (wash to remove mildew, caulk open joints, wet sand rough spots, spot surfaces, per Attachment 2, specifications, entitled, “Gambrill House Three Porches & Balcony Preservation: Project Specifications”, consisting of 30 pages.

4) SIDE /EAST PORCH

1) Replace existing non-historic steps, match existing in size, shape, and details. Use preservative treated lumber rated for ground contact for stringers and structural members, use Number 1 Douglas Fir in full length pieces matching thickness and profile of existing treads and risers, prime all bare wood surfaces, apply two topcoats matching extant colors. Prepare and paint all painted wood surfaces per Attachment 2, specifications, entitled, “Gambrill House Three Porches & Balcony Preservation: Project Specifications”, consisting of 30 pages.

2) Repair, prepare, prime and paint metal handrails.

3) Remove deteriorated and damaged woodwork. Replace damaged components with

Spanish cedar or Sapele milled to match dimensions and profile.

4) Prepare, prime metal roof with a coating of an acrylic elastomeric system that offers protection from extreme environmental conditions and heat. Product should meet the following criteria at a minimum:

• Low viscosity material

• Meet all VOC regulations

• Be water soluble and easily removed/cleaned up without hazardous solvents.

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• Should meet the following ASTM standards, D522, D2370, D412, ASTM 1653 and ASTM G154

5) Replace gutters, leaders add gutter guards.

6) Prepare (wash to remove mildew, caulk open joints, wet sand rough spots, spot

5) REAR/WEST PORCH

1) Provide shoring to facilitate the removal and repair of the southwest corner post.

Repair damage column base to reestablish adequate bearing. Install new base trim with Spanish cedar or Sapele milled to match dimensions and profile of adjacent posts.

2) Remove deteriorated and damaged woodwork. Replace damaged components with

Spanish cedar or Sapele milled to match dimensions and profile.

3) Prepare (wash to remove mildew, caulk open joints, wet sand rough spots, spot prime bare wood, back prime new wood elements) and paint all painted wood

4) Demo metal roof, gutter, and roof substrate.

5) Remove, repair, and replace ceiling boards.

Cover roof deck and built-in gutter with roof butyl underlayment that meets the following criteria and install per manufacturer specifications.:

• Heat resistant up to 300 degrees F

• Membrane forms watertight seal around roofing fasteners

• Membrane forms watertight overlaps without the need for additional treatment

• Plastic can be easily removed and disposed

6) Replace metal roof, gutters, leaders, junction boxes and downspouts. Add gutter guard. Install splash guard where roof valley discharges into gutter.

7) Reroute mini split condensation line for positive flow.

6) DEMOBILIZATION and SITE RESTORATION

1) Remove scaffolding, site fencing, and lay down area permitter fencing, any storage trailers, and project generated waste and surplus materials.

2) Repair / restore damaged turf by smoothing and filling ruts with topsoil and sod.

Notes:

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1) Entrance and egress to the Gambrill Mansion must remain accessible and safe for pedestrians.

Explain safety procedures to be implemented to prevent visitors/staff from entering the mansion and staging area during the construction period, and for maintaining safe passage along adjacent walkways, and other outdoor recreational areas for visitors and staff.

2) Only NPS employees and staff traffic go in and out of the Gambrill Mansion. At least one entrance to the mansion shall remain accessible and free of obstruction at all times.

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