Specification:Stone repair through patching and grouting

__NUMBEREDHEADINGS__ =GENERAL=

DESCRIPTION
 This specification provides guidance for stone repair through patching and grouting. This document should only be used to address previously repaired or existing cracks that are non-structural in nature.  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. All work described herein and related work must conform to the Secretary of Interior’s Standards for the Treatment of Historic Properties. The Contractor shall provide all labor, materials, equipment, and operations required to complete the rehabilitation work indicated herein. 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 61. Such person is referred to in this document as the Architect. 

SECTION INCLUDES
 Stone masonry repair through mortar patching Repair of vertical cracks</li> </ol>

RELATED SECTIONS
<ol type="A"> Specification:Historic mortar</li> Specification:Masonry restoration</li> Specification:Masonry cleaning</li> Specification:Joint sealers</li> </ol>

SUBMITTALS
The Contractor shall submit to the Architect: <ol type="A"> A detailed schedule of the areas for repair, including an assessment of the problem areas, historic mortar analysis, and detailed procedures for masonry repair for approval.</li> Product data for all manufactured masonry consolidation, grouting, and patching materials. Manufacturer’s product data shall include certification of compliance with specified standards and instructions for handling, storage, and installation of the material, and Material Safety Data Sheets for each material.</li> Samples of the following masonry repair and replacement materials for approval of color and texture match. No masonry restoration work shall proceed until all samples are approved. Once a matching mortar color is achieved, placement of on-site mock-ups may begin.  Cured pointing mortar for stone masonry</li> Cured stone patching mortar</li> Pointing mortar: Prepare portable samples using drywall channel or similar material the approximate width of a mortar joint.</li> Patching mortar: Prepared samples shall be a minimum size of 3 inches x 3 inches by one-half inch or 3 inches diameter by one-half inch thickness.</li> </ol> </li> </ol>

QUALITY ASSURANCE
<ol type="A"> Work Experience: The Contractor to perform the work in this section shall have demonstrated experience approved by the Architect, ideally a minimum of seven years experience in historic masonry restoration and shall have successfully completed at least three projects of similar scope within the previous five years. 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 &amp; Reconstructing Historic Buildings.</li> The Contractor shall not change sources or manufacturers of mortar or patching materials during the course of the work.</li> Warranty: The Contractor shall provide a warranty in writing against defects in material and installation for a period of five (5) years.</li> </ol>

MOCK-UPS
<ol type="A"> The Contractor shall provide samples of stone and mortar matches for approval by the Architect of color and texture. After approval the Contractor shall prepare test panels of the following work in Stone Masonry Restoration: <ol> <li>All personnel proposed for work on the project shall prepare 3 feet x 3 feet samples demonstrating stone restoration techniques, including mortar removal, repointing, mortar patching and/or grouting. </li> <li>Mock-ups will be reviewed after the mortar removal and patch preparation, and again after completion of repointing and patching work. </li> <li>Mock-ups shall display the full range of materials and workmanship required for completion of the project for approval by the Architect.</li> <li>Color matching: The Contractor shall match existing mortar color(s) for masonry pointing sample. The Contractor shall place the initial sample panel using the mix from the approved sample. The sample panel must be cured in the same manner as is expected for the work based on anticipated temperatures. </li> </ol> </li> <li>The Contractor shall prepare up to three additional mock-ups of each mortar color, joint type, and patching color with no further compensation. Approved test panel(s) shall become part of the work and shall serve as the quality standard for all subsequent work.</li> </ol>

DELIVERY, STORAGE, AND HANDLING
<ol type="A"> <li>Materials shall be delivered to the site in original packaging, unopened, with manufacturer’s name and product identification thereon. Cementitious materials shall be protected from contamination by foreign matter and deterioration by moisture or temperature. Contaminated or deteriorated material shall not be used. Products stored longer than six months shall not be used.</li> <li>Masonry materials shall be stored in such a manner as not to interfere with the operation and daily maintenance of the facility. Proposed storage locations shall be approved by the Architect.</li> <li>Store liquids at temperatures between 40 and 85 degrees Fahrenheit. Do NOT allow liquids to freeze.</li> </ol>

PROJECT / SITE CONDITIONS
<ol type="A"> <li>Normal conditions for the work of this Section shall be defined as when the air and surface temperatures are 40 degrees F and rising or less than 90 degrees F and falling or as directed by manufacturer of restoration materials. Work shall not commence when rain, snow, or below-freezing temperatures are expected within the next 24 hours. All surfaces shall be free of standing water, frost, and ice.</li> <li>The Contractor is responsible for protecting existing adjacent materials and surfaces during the execution of the work. Provide all necessary protection and work procedures to avoid damage to existing material assemblies not a part of the work in this Section. The Contractor shall: <ol> <li>Minimize levels of dust during mortar removal and masonry repointing operations.</li> <li>Protect open copings, reglets, and other vulnerable areas from water penetration to prevent leakage during the course of the work. Open areas shall be left exposed overnight or when inclement weather is predicted.</li> <li>Temporarily remove and store metal downspouts during masonry restoration work. Install temporary drainage leaders if required. Reinstall immediately upon completion of work in the immediate area. Protect open boots at grade from accumulation of masonry debris.</li> <li>Protect existing gutters and gutter outlets from damage and accumulation of mortar debris during restoration of roof elements.</li> <li>Protect window sashes and frames with plywood or other sturdy barrier during repointing and repair of masonry around window openings.</li> <li>Protect the existing roof surfaces from damage during the course of the masonry restoration work. Repair all damage to wood and metal roofing, gutters, flashing, etc., to the satisfaction of, and at no additional cost to, the owner.</li> <li>Remove and store light fixtures, signage, security devices and miscellaneous appurtenances from masonry surfaces to be repointed. Provide temporary protection for exposed fixture boxes.</li> </ol> </li> <li>The Contractor shall provide visible barriers and/or warning tape around the perimeter of the work area for visitor protection. Nearby vehicles and adjacent structures shall be protected from damage during the course of the work.</li> <li>Stone, brick, mortar, waste material, packaging, and other debris associated with the masonry work shall be disposed of in accordance with local, state, and federal environmental regulations. The Contractor shall remove debris from masonry restoration work from the site on a daily basis and at the completion of the work.</li> <li>Contractor shall coordinate masonry repairs with the other trades involved in exterior and interior restoration work, including but not limited to masonry cleaning, sealing, and painting.</li> </ol> =PRODUCTS=

MATERIALS
<ol type="A"> <li>Pointing and Patching Materials – Job-Mixed <ol> <li>Lime: ASTM C-207, Type S</li> <li>Portland Cement: ASTM C-150, Type I, non-staining and without air entrainment. Gray and white Portland cement may be combined as required to match existing mortar.</li> <li>Sand: ASTM-C-144, free of clay, silt, soluble salts and organic matter and shall match the color and texture of the original mortar sand.</li> <li>Water shall be potable and free of deleterious amounts of oil, soluble salts, alkali, acids, organic impurities, or other substances that may impair the strength or bond of the finished mortar.</li> <li>Mortar colorant, if required, shall match the color of the existing mortar. Mortar colorant shall be a standard product by a recognized manufacturer of this type of product. Colorant products and manufacturers selected shall be approved by the Architect. </li> </ol> </li> <li>Pointing and Patching Materials – Factory-Mixed: The Contractor shall have the option of providing factory-mixed pointing and patching mortars subject to approval of required technical data, samples, and mock-ups by the Architect.</li> <li>Manufacturers: Obtain masonry materials and units from an established plant having the capacity and facilities for producing material of specified quality and finish, and in sufficient quantity so as not to delay progress of the work. Plant shall be that of a producer recognized by the industry as a supplier and/or manufacturer of this type of material, who can show successful completion of work of comparable quality and scope.</li> </ol>

MIXES
<ol type="A"> <li>Mortar mixes shall be of the appropriate strength and hardness for the masonry units and existing mortar. The mix shall match the composition, color, and texture of existing mortars. Refer to Section 04100 – Historic Mortar.</li> </ol>

ACCESSORY MATERIALS
<ol type="A"> <li>Stainless steel pins for anchoring patches shall be Type 304 or 316 stainless-steel all-thread rods, one-quarter inch diameter. Length shall be as required by the depth of the patch. All other embedments such as eye bolts to be used for anchoring reinforcing pins and wire shall be stainless steel.</li> <li>Stainless-steel rods for stitching vertical cracks shall be Type 304 or 316 stainless-steel all-thread rods, one-quarter inch diameter or smaller as required to make repair. Length shall be approximately 24 inches or as required to span crack 12 inches on either side. </li> <li>Epoxy adhesive for embedding anchors and pins shall be a high modulus epoxy resin conforming to ASTM C-881, Type I, II, IV, and V, Grade 3 epoxy resin adhesives.</li> <li>In high traffic areas with a high risk of shear failure, threaded nylon pins may be approved to reduce the amount of stone damage in case of failure. </li> </ol>

MIXING PROCEDURES
<ol type="A"> <li>Job-Mixed Mortar: <ol> <li>Mix mortar in accordance with ASTM C-270.</li> <li>Measure materials by volume or equivalent weight as indicated. Do not measure by shovel.</li> <li>Mix ingredients in a clean mechanical batch mixer for three to five minutes.</li> <li>Mortar shall stand for 20 minutes prior to use to allow for initial shrinkage. Place mortar in final position within two hours of mixing. Do NOT retemper or use partially hardened mortar.</li> </ol> </li> <li>Proprietary Mortars: Mix in accordance with manufacturers printed instructions.</li> </ol> =EXECUTION=

GENERAL
<ol type="A"> <li>Complete masonry cleaning prior to masonry repair and repointing. The Contractor shall match new patching materials and mortars to the color of the cleaned stone.</li> <li>The Contractor shall examine areas and conditions under which masonry restoration is to be performed and notify the Architect of any conditions detrimental to the proper and timely completion of the work. Work shall NOT commence until all unsatisfactory conditions have been adequately corrected.</li> </ol>

MASONRY REPOINTING
<ol type="A"> <li>Refer to Specification:Removal of mortar joints and repointing.</li> </ol>

REMOVAL OF EXISTING PATCHES AND PREPARATION OF SUBSTRATE
<ol type="A"> <li>Any existing patches showing visible signs of failure such as cracking or delamination that may need replacement should be noted on the Drawings and approved by the Architect. Where a single small stone requires extensive patchwork and the Architect deems absolutely necessary, the entire stone shall be removed and a patch installed. </li> <li>The Contractor shall remove existing patches by manual chiseling or using a low pressure (&lt;40 psi) pneumatic chisel. Grinding with a carborundum blade will be permitted only after review and approval of the grinding technique by the Architect. Final chipping of the corners of the area to be patched shall be done by hand.</li> <li>The Contractor shall chip damaged areas back to sound material, ensuring a uniform minimum depth of ¾ inch. Remove additional stone only as required to provide for a neat square patch. Back bevel the top and sides of the patch area to provide a mechanical key for the new patching material.</li> <li>Wash area to be patched clean of dust, grit, and other debris.</li> <li>Where stone patches exceed 20 square inches in area or three inches in depth, the Contractor shall install stainless-steel pins as required to secure the patch to the existing substrate. The Contractor shall allow for one pin per 20 square inches of surface area to be patched. Pins shall penetrate a minimum of one third the thickness of the patch to be installed but under no circumstance be allowed less than two inches mortar cover.</li> <li>The diameter of the holes for stainless steel anchor pins shall be drilled one-eighth inch greater than the diameter of the pins. The use of hammer drills is not permitted. The Contractor shall anchor pins in specified setting adhesive.</li> </ol>

MORTAR PATCHING
<ol type="A"> <li>Thoroughly wet area to be patched to prevent suction of moisture from the patching material. Apply a slurry coat of approved mortar to the substrate.</li> <li>Install mortar patching material in lifts to build the required depth of patch in accordance with the manufacturer’s published instructions. The surface shall be tooled to match the adjacent stone texture.</li> <li>Keep the mortar patches damp for 24 hours using damp burlap, plastic sheeting or other membrane as required.</li> </ol>

VERTICAL CRACK REPAIR
<ol type="A"> <li>The Contractor shall rake horizontal masonry joints to approximately 12 inches on either side of the crack to be repaired and a minimum depth of two inches or to sound mortar. Rake entire crack down to sound mortar (where applicable). See Section 04100.01 Removal of Mortar Joints and Repointing.</li> <li>Where cracks extend through individual stones, the Contractor shall remove and replace cracked stones with sound material toothed into the adjacent masonry.</li> <li>Repoint all joints full depth, embedding stainless-steel reinforcing rods at least 1½ inches behind the finish joint surface to a minimum distance of 12 inches on either side of the crack. Space rods approximately 12 inches o.c. vertically. Ensure rods are set in a full mortar bed. Finish joints to match existing.</li> </ol>

FINAL REPORT
The Contractor shall: <ol type="A"> <li>Revisit the site with the Architect to compare the finish and color of the repair to see if the desired affect has been achieved after the repairs have been executed and new mortar has cured at least 30 days.</li> <li>Document the work, before, during, and after, with photographs.</li> <li>Provide a written summary of the project and results upon final inspection and approval. The summary shall outline steps taken or new findings not addressed in the initial documentation.</li> </ol>