Installation of new limestone to match existing specification

Technical procedures are supplied by GSA only as a reference. All procedures have been reviewed for general consistency with federal standards for rehabilitating historic buildings. 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.

Part 1 – General

1.01 Description

1. This specification provides guidance for the selection and installation of new limestone to match existing for dutchman repair and selective replacement.
   1. This specification has been developed for use on historic properties (defined as any district, site, building, structure, or object that is listed in or eligible for listing in the National Register of Historic Places) and provides an overview of accepted practices. Site-specific specifications, when appropriate, will be provided by the Architect.
   2. All work described herein and related work must conform to the Secretary of the Interior’s Standards for the Treatment of Historic Properties.
   3. The Contractor shall provide all labor, material, equipment, and operations required to complete the rehabilitation work indicated herein.
   4. All work described herein and related work must have the approval of a Cultural Resources Manager, Conservator, Historic Architect, or other professional who meets the standards outlined in the Secretary of the Interior’s Standards – Professional Qualifications Standards pursuant to 36 CFR.

1.02 Section includes

1. New limestone to match existing, for Dutchman repair
2. New limestone to match existing, for selective replacement

1.03 Related sections

1. Section 01100-07-S for general project guidelines to be reviewed along with this procedure. These guidelines cover the following sections and should be reviewed prior to performing this procedure and should be followed, when applicable, along with recommendations from GSA Historic Preservation):
   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)
   9. Historic Building Treatment Procedures

1.04 Quality assurance

1. The Contractor performing the work described in this Section shall have a minimum of five years experience in similar masonry work on historic buildings and shall have successfully completed at least three projects of similar scope within the previous five years. Successful Masonry Contractor shall submit a list of at least five similar completed projects to GSA and the Architect including a name of a person (Using Agency, Manager, Architect, etc.) who may be contacted for information concerning said projects.
2. He/she shall demonstrate a working knowledge of The Secretary of the Interior’s Standards for the Treatment of Historic Properties with Guidelines for Preserving, Rehabilitating, Restoring & Reconstructing Historic Buildings.
3. Masons will be expected to be well versed with historic construction, methodologies, conditions and solutions.
   1. Superintendent and foreman for work in this section assigned to this project shall each have a minimum of 5 years experience with this type of repair work. References of projects they have completed shall be submitted to the Architect by the successful bidder. The project superintendent and foreman assigned to this project shall not be changed throughout the duration of the work without written request to and consent of the Architect and GSA.
   2. Installer qualifications: Employ only masons experienced in restoration, repairing and repointing historic stonework with a minimum of 10 years project experience and provide written and photographic documentation of restoration skills.
4. Replacement stone is to be matched to a cleaned area of existing stone. Chemicals and techniques for cleaning must be approved by Project Team and/or GSA Historic Preservation and a mockup approved prior to implementation.
5. Source Limitations for Stone: Obtain all stone for project from one North American quarry, with resources to provide materials of consistent quality in appearance and physical properties. If a North American quarry can not match the existing stone, permission may be granted by the Project Team to obtain stone from overseas.
   1. Approval of sample is for color, texture, and blending of stone and aesthetic qualities of finish.
6. Prior to installation or placement of any new mortar, Masonry Contractor shall remove mortar, in a non damaging manner as approved by GSA Historic Preservation, in an area designated by the Architect. Samples of new mortar shall be placed and allowed to cure for Project Team and/or GSA Historic Preservation review. Rejected samples shall be removed and replaced with new until a match satisfactory to the Project Team and GSA Historic Preservation has been placed.
7. Pre-installation Conference: Conduct conference at Project site in conjunction with start-up meeting.

1.05 Submittals

1. The Contractor shall submit to the Architect or GSA Approving Official:
   1. A detailed description and schedule of the areas to be repaired, including an assessment of the problem surfaces, and any necessary testing, and proposed general cleaning techniques, etc., for approval once mockups are completed and approved.
   2. Work procedures and materials that the Masonry Contractor proposes to actually use for each repair that is to be performed, prior to the demonstration of any sample repairs on the building.
   3. Product Data: For stone variety proposed for use on Project, including test data indicating compliance with physical properties to match appearance, and by referenced ASTM standards.
   4. Samples for Verification:
      1. Include at least 3 samples in each set for each type of stone, exhibiting extremes of the full range of color and other visual characteristics expected in completed work. Samples provided must be in a range to match the existing stone on site, and will establish the standard by which stone provided will be judged.
   5. The manufacturer’s product literature for all proprietary products. If a custom formula is used, all ingredients must be documented and submitted for approval as with proprietary formulas. Product literature shall include specification data, Safety Data Sheets (SDS), and instructions for storage, handling, and use.
   6. A project safety plan to include at minimum: any personal protective equipment to be used by the contractor’s staff such as disposable clothing, gloves and safety glasses, procedures for emergencies and accidents, documentation of staff training in use of equipment and/or chemical products as required by the manufacturers.

1.06 Samples

1. For each exposed material required for replacing or repairing existing materials, including mortar samples, patching materials, Dutchman stone, and brick to match existing.
2. Submit for Project Team’s approval. Label samples to indicate product, characteristics, and locations in the Work. Samples will be reviewed for color and appearance only. Compliance with all other requirements is the exclusive responsibility of the Masonry Contractor. Furnish samples of each type and finish of stone, showing the full range of color and texture expected in the finished work. In addition, submit one (1) full size sample of each type and finish, falling in the average color and texture range.

1.07 Testing and mockups

1. Contractor, at inconspicuous locations designated by the Project Team and GSA Historic Preservation, shall perform small test patches (no larger than 6 inches by 6 inches) for all products to be used. Testing will determine the best method(s) to perform the work and ensure that the chosen products do not cause harm.
2. Following testing, mockup panels shall be created (mockup panels may incorporate successful test patches) using the chosen methods. Size and location of mockup panels shall be determined by the Project Team and GSA Historic Preservation.
3. The Contractor, at inconspicuous locations designated by the Project Team and GSA Historic Preservation, shall prepare mockups of all proposed work, as applicable to determine the best method to perform the work. The “best method” shall be defined as that which successfully installs the new limestone without causing damage to surrounding existing limestone.
4. The mockup shall include an evaluation of the materials and techniques proposed for the protection of adjacent and surrounding areas from the tools and products used to install the limestone.
5. Any testing, demonstrations, or mockup that is rejected by the Project Team shall be removed in its entirety without damage to the surrounding masonry and a new demonstration/mockup shall be performed for the project team’s review.
6. Utilize the same craftsmen, materials and installation methods in the mockup as intended for the final work. Schedule the installation so that the mockup may be examined, and any necessary adjustments made, prior to commencing fabrication of the Work. Replace unsatisfactory item as directed. When accepted, mockup shall become part of the work and serve as the standard for materials, workmanship, and appearance for such work throughout the project. Furnish mockups for the following items:
   1. Remove and install new patch at 2 locations in stone indicated to be patched.
   2. Mockup will be judged for color, tooling, and texture of mortar. Dutchman must blend in with the existing stone, appearing seamless at a distance of 5 feet.
   3. Install Dutchman in 2 small areas at least 1 inch in diameter in stone indicated to be patched.
   4. Rake out joints and remove existing material in 2 separate areas approximately 36 inches high by 72 inches wide and repoint one of the two areas for each type of masonry to be repaired.
7. Each worker proposed for work on the project shall prepare a mockup panel of each activity they are to work on. Workers whose mockups are not approved shall not be permitted to work on the project.
8. Approved mockups shall become part of the work and shall serve as the quality standard for all similar work.

1.08 Delivery, storage, and handling (as applied to products and materials)

1. The Contractor shall:
   1. Coordinate delivery and storage of stone with GSA Building Management and General Contractor / other trades

1.09 Safety

1. The contractor shall only use chemical products whose safety data sheets (SDS) have been reviewed and considered acceptable by the Government. Any project surfaces containing lead-based paint, as disclosed by the Government, shall be handled by the contractor in accordance with OSHA (29 CFR 1926.62), EPA (40 CFR 261) and State regulations. Any lead-based paint or coating that is removed in a project resulting from this scope shall undergo Toxicity Characteristic Leaching Procedure (TCLP) testing by the contractor. The contractor shall dispose of any lead-paint waste as hazardous if it fails the TCLP.
2. Any paint or coating required to be removed which has not been disclosed by the Government to contain lead, shall be tested for lead by the contractor. All paints or coatings testing positive shall be handled and disposed of as lead-based.
3. The contractor shall isolate the work area with cones, tape or similar means as possible for the duration of the project, to prevent unauthorized individuals from entering the immediate work area.
4. For any work required on elevated surfaces (4 feet or more above the ground) the contractor shall install and use any ladders, scaffolding or platforms in accordance with OSHA regulations (29 CFR Subpart M).

1.10 Project/site conditions

1. Weather Conditions: Do not proceed with the Work during inclement weather or when weather forecasts are unfavorable, unless the Work will proceed in accordance with the manufacturer’s requirements and instructions and any agreements or restrictions of the Pre-Construction Conference.
2. Cold Weather Requirements: Provide temporary protection for stone masonry Work completed less than 24 hours, when the ambient temperature is less than 40℉ and falling. Do not build upon frozen Work. Do not install stone units which have a surface temperature of less than 33℉ or which have a film of frozen water or frost. Do not use fuel fired heaters directly against stone.
3. The Contractor is responsible for protecting existing adjacent areas and materials during the execution of the work and shall provide all necessary protection and follow all necessary work procedures to avoid damage to existing material assemblies and vegetation not a part of the work of this Section.
4. If applicable, the Contractor shall coordinate operations with the other trades involved in exterior and interior restoration work.
5. All Contractor personnel performing treatment operations shall be provided by the Contractor with gloves, respirators, protective clothing and any other personal protective equipment (PPE) as recommended by the manufacturer of the products used during the work and required by local, state, and federal regulations.

1.11 Demolition

1. Unless otherwise noted, areas of required demolition of existing limestone shall require salvage of the removed limestone for re-use, when possible.
2. During any demolition, cutting joints or other dust-generating work, dust shall be controlled. Dust is not permitted to migrate from jobsite, settle on cars, or negatively impact employees and pedestrians.
3. The Masonry Contractor shall protect the building and contents from damage due to dust, falling debris, rain, snow, or other weather conditions. The Masonry Contractor shall be aware if dry sawing/grinding of joints causes dust to infiltrate through windows, doors, dust enclosures and/or air intake grilles, the Masonry Contractor will be expected to stop work and employ other methods of cutting out joints such as wet sawing, or provide adequate sealing off of windows, doors, and/or air intake grilles as approved by the GSA’s Representative. The Masonry Contractor shall be liable for the cost of the facility clean up to the satisfaction of the GSA.
4. Traffic pads shall be used to protect roofing and in other areas as needed.
5. Debris as defined by the GSA becomes the property of the Masonry Contractor and shall be removed from the site daily and suitably disposed of away from the project site. No debris shall be allowed to accumulate in or around the building.

1.12 Protection of new materials

1. Take all necessary precautions to protect all materials from damage during transportation, storage and installation. If damaged materials are incorporated into the work, as determined by the Architect, the work shall be removed and replaced as directed by the Architect at no additional cost to the contract.
2. Cements, mortars and limes shall be delivered in original sealed containers plainly marked with name and brand of manufacturer, and kept dry until used.
3. Cements, mortars and limes which are defective or show partial set or caking shall not be used and shall be immediately removed from the premises.
4. Sand shall be stockpiled on platforms or otherwise protected from direct contact with the ground and shall be so stockpiled and handled as to prevent the inclusion of any foreign or deleterious substances.
5. Store any materials which are temperature sensitive in areas where temperatures comply with manufacture’s recommendations and instructions.
6. Epoxy adhesive materials shall be delivered to the job site in clearly labeled unopened cans. All labels shall clearly indicate:
   1. Name of manufacturer.
   2. Manufacturer’s project name and product number.
   3. Manufacturer’s lot number.
   4. Mix ratio.
   5. Conformance with the injection adhesive specification.
   6. SPI hazardous material rating and appropriate warnings for handling

1.13 Stain prevention

1. Immediately remove mortar and soil to prevent them from staining the face of stone masonry.
   1. Protect base of walls from rain-splashed mud and mortar splatter by coverings spread on the ground and over the wall surface.
   2. Protect sills, ledges, and projections from mortar droppings.
   3. Protect surfaces of window and door frames, as well as similar products with painted and integral finishes, from mortar droppings.
   4. Turn scaffold boards near the wall on edge at end of each day to prevent rain from splashing mortar and dirt on completed stone masonry.

Part 2 – Products

2.01 Materials

1. Limestone
   1. Sourced from material salvaged from site and approved by Project team and/or GSA Historic Preservation.
   2. New Limestone to match existing as approved by Project Team and/or GSA Historic Preservation and in compliance with ASTM C 568.
      1. Products: Subject to compliance with requirements, provide stone varieties that match existing for use in Dutchman repairs and selective replacement.
   3. Match existing stone for color, finish, and other stone characteristics relating to aesthetic effects.
2. Mortar
   1. New mortar shall match existing mortar in all properties including color, texture, aggregate size and appearance, strength, porosity, and chemical make-up.
   2. Lime shall be hydrated lime conforming to ASTM C1489. The use of quick-lime is not allowed.
   3. Sand for mortar shall be a clean, washed, uniformly well-graded masonry sand conforming to the requirements of ASTM C144.
      1. Sand color, size and texture shall match the original as closely as possible, and per gradation chart in mortar analysis report attached.
   4. Water shall be clean, potable and free from deleterious amounts of acids, alkalis or organic materials.
   5. Lightly blast all surfaces of the new limestone which will be exposed in the finished work to produce a texture and overall appearance to match the adjacent (weathered) material.
   6. Masonry anchors for stone replacement shall be ASTM Type 304 stainless steel, size, type and configuration to match original or as otherwise approved by the Architect.
   7. Epoxy materials to anchor loose stone shards or to adhere Dutchman patches in limestone shall be:
      1. Sikadur 32 Hi-Mod or Sika 31 Hi-Mod Gel by Sika Corporation
      2. Pro-Poxy 204 or Pro-Poxy 300 Paste by Unitex

2.02 Fabrication

1. Fabricate stone to comply with sizes, shapes, and tolerances recommended by applicable stone association or, if none, by stone source, for faces, edges, beds, and backs.
   1. For limestone, comply with recommendations in ILI’s “Indiana Limestone Handbook.”
2. Cut stone to produce pieces of thickness, size, and shape finish of existing to be replaced, including details on Drawings. Dress joints (bed and vertical) straight and at right angle to face unless otherwise indicated.
3. Carefully inspect stone at quarry or fabrication plant for compliance with requirements for appearance, material, and fabrication. Replace defective units before shipment.
   1. Clean sawed backs of stone to remove rust stains and iron particles.
4. Finish exposed faces and edges of stone to match existing.
   1. Finish: To match existing.

Part 3 – Execution

3.01 Repair procedure: Remove loose/bad patches in stone and install Dutchman repair

1. Carefully remove the patch and cut out deteriorated stone using hand tools so as to completely remove the deteriorated portion of the stone and to allow for a minimum Dutchman repair thickness of 2 inches. Carefully shape to form square edges and form approximate 90° corners for the patch.
   1. Where the configuration of the stone and Dutchman patch will permit, fine masonry saws may be used, if sufficient skill has been demonstrated on non-historic material mockups.
2. Clean patch area by blowing out with compressed air and rinsing with clean water. Allow to dry.
3. Fabricate Dutchman patch from limestone to match the original profile, finish, texture and color of the stone. The size of the patch should be slightly smaller than the hole such that it fits with a maximum joint dimension showing on any exposed face of 1/16 inch and the profile blends in continuously with the surrounding stone.
4. Epoxy the Dutchman patch in place, carefully filling all sides of the patch with epoxy without allowing it to blemish any exposed surfaces.
5. For Dutchman patches over 12 inches in length in any direction or in smaller pieces located in soffits where pinning is practical, install 1⁄4 inch diameter stainless steel threaded pins.
6. Tool epoxy joint line smooth without smearing epoxy on to any exposed surfaces. Support patches in place where necessary until epoxy cures.

3.02 Installation of new replacement limestone

1. Remove damaged stone being careful not to damage adjacent material. Remove all pointing and bedding mortar, being careful not to damage the stone around the joints.
2. Use limestone that matches the original profile, finish, texture, and color of the existing stone.
3. Mortar the replacement stone in place using mortar as specified in this specification and approved by the Project team and/or GSA Historic Preservation. Ensure that mortar joint profile matches existing.
4. For pieces of stone over 12 inches in length in any direction or in smaller pieces located in the soffits where pinning is practical, install ¼ inch diameter stainless steel threaded pins.

3.03 Clean up

1. Upon completion of the work specified herein, clean up and dispose off site all debris and unused materials. Repair any damage incurred under this Contract to its previous condition and leave all areas in a clean and tidy condition. Remove excess mortar and sealant from surfaces as the Work progresses and before it hardens on the surface. Clean the stone by washing with water and bristle brushes. Remove stains, dirt, and other discolorations. Do not use acids, cleaning compounds, or wire brushes. Repair any damage incurred under this Contract to its previous condition and leave all areas in a clean and tidy condition.

3.04 Final report

1. The Contractor Shall:
   1. Provide a final report of completed work, including all approved submittals and photographs of the areas cleaned that were taken before, during, and after the work.
   2. Provide a written summary of the project and results upon final inspection and approval. The summary shall include a discussion of steps taken or new findings not specified in the initial documentation. Summary should also include any applicable ongoing care and warranty requirements.