Specification:Historic terra-cotta and ceramic properties and in-kind replacement

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=GENERAL=

DESCRIPTION
 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 the 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
 Terra-cotta and ceramic properties Replacement and substitute materials Procedures for replacement</li> </ol>

RELATED SECTIONS
<ol type="A"> Section 04214.02 – Terra-cotta Patching and Glaze Repair</li> Section 04214.03 – Replacement Anchoring</li> Section 04100 – Historic Mortar</li> Section 04400.01 – Identifying Masonry Types and Failures</li> Section 07900 – Joint Sealants</li> </ol>

DEFINITIONS
<ol type="A"> Terra-cotta. Terra-cotta is an enriched molded clay brick or block. Terra-cotta refers to a high grade of weathered or aged clay that, when mixed with sand or with pulverized fired clay, can be molded and fired at high temperatures to a hardness and compactness not obtainable with brick.</li> Glazed Terra-cotta. Terra-cotta blocks are generally finished with a glaze—a slip glaze (clay wash) or an aqueous solution of metal salts, brushed or sprayed on the air-dried block before firing. Glazing changes the color, imitates different finishes, and produces a relatively impervious glass-like surface on the weather face of the final product.</li> Architectural Terra-cotta. Architectural terra-cotta is a term used to distinguish the masonry material used to form and decorate buildings from other forms of terra-cotta that have been and continue to be used primarily in domestic ceramics and sculpture.</li> Fireproof Terra-cotta. Fireproof terra-cotta is a form of hollow, unglazed (rough-finished) terra cotta block extruded as tile-like units. These inexpensive, light-weight, and fireproof units were well suited for use with I-beams and were used between floor beams, as sheathing of skeletal iron or steel frames, and inside walls and partitions.</li> Ceramic Veneer. Ceramic veneer was developed in the 1930s and is a glazed terra-cotta tile that is ribbed on the back (similar to bathroom tile). Unlike architectural terra-cotta, ceramic veneer tiles are not hollow cast. Ceramic veneer terra-cotta is often attached to a grid of metal ties anchored to the building.</li> </ol>

SUBMITTALS
<ol type="A"> The Contractor shall submit a detailed schedule to Architect for approval of the work to be conducted, including an assessment of the problem areas, historic terra-cotta analysis, and detailed procedure for terra-cotta replacement and repair;</li> The Contractor shall submit manufacturer’s product literature to the Architect for new terra-cotta or cast stone, and anchoring material and products specified. For new terra-cotta or cast stone, provide test data as described in Paragraph 1.05B below. Product literature shall also include specification data, Material Safety Data Sheets and instructions for storage, handling, and use;</li> The Contractor shall submit Shop Drawings to the Architect for review and approval to include the following:  Production details, construction of the terra-cotta / cast-stone replacement units, dimensions, and relationship to adjacent material in sufficient detail to address manufacture, handling, and erection. Field verification of required dimensions is the responsibility of the Contractor and the terra-cotta manufacturer. Details of sections and connections for fastening the block units; anchorage, flashing, counterflashing, and accessory items. Details shall be at least ½ full size.</li> Separate identification marks assigned by the Contractor for each replacement unit. Units should be labeled with this identification mark on the shop drawings to show the location of the replacement units for installation. Each replacement unit should be permanently marked with year of manufacture and identification mark.</li> </ol> </li> <li>Material Samples <ol> <li>Glaze and Body: Proposed glaze and body samples for new terra-cotta or cast stone shall be submitted to the Architect within the specified time period. Samples should cover the expected range of color and texture of surface finish as required to match to match original finish. Samples selected and approved by Architect shall be standard for reproduction units.</li> <li>Anchors: Submit two of each of the dowels, anchors, bolts, and fasteners to be used in the work under this section. Samples will be approved by the Architect.</li> </ol> </li> <li>Test Reports: <ol> <li>The Contractor shall arrange for sampling and testing of new terra-cotta prior to shipment, allowing at least 30 days from time of sampling for completion of tests. Expense of sampling and testing is to be borne by Contractor.</li> <li>All testing should be performed by an independent testing facility meeting the requirements specified in the “Recommended Requirements for Independent Laboratory Qualifications” published by the American Council of Independent Laboratories and ASTM E 699.</li> </ol> </li> <li>Statement of Application. The Contractor shall submit letter from manufacturer verifying that new terra-cotta units are suitable for intended use.</li> </ol>

QUALITY ASSURANCE
<ol type="A"> <li>Work Experience. The Contractor to perform the work in this section shall have a minimum of ten (10) years of recent experience in terra-cotta restoration and installation. Such experience must include projects of comparable scope and extend to this project. <ol> <li>The qualifying firm must designate an individual with commensurate experience to act as the “Terra-Cotta Foreman” for purposes of this contract. Said Terra-Cotta Foreman designation must be approved by the Architect. 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.</li> </ol> </li> <li>Testing: Where new terra cotta is required, a minimum of six (6) representative samples of existing terra-cotta material will be submitted for testing. The following tests will be undertaken by a laboratory that meets the conditions specified in 1.04 E above to correctly identify the characteristics of the original material: <ol> <li>Water Absorption (24 hour)</li> <li>Boil Absorption (1 hour)</li> <li>Moisture Expansion (reheat test)</li> <li>Water Uptake with and Without Glaze</li> <li>Compressive Strength</li> <li>Petrographic Examination</li> <li>Glaze Adhesion</li> <li>Coefficient of Thermal Expansion</li> </ol> </li> <li>Manufacturers: The Contractor shall: <ol> <li>Obtain materials from manufacturers that will send a qualified technical representative to the project site for the purpose of advising the Terra-Cotta Foremanand those undertaking the installation work of the procedures and precautions for the use of their materials.</li> <li>Obtain terra-cotta or cast-stone units from an established specialty plant having the capacity and facilities for producing material of specified quality and finish, and in sufficient quantity so as to not delay progress of the work. Plant shall be that of a producer recognized by the industry as a manufacturer of this type of material, who can show successful completion of work of comparable quality and scope.</li> </ol> </li> <li>Fabrication. Do NOT proceed with fabrication of products prior to completed review and approval of shop drawings, and approval of material samples and mock-up.</li> <li>Warranty: 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"> <li>Prior to the start of demolition and installation, the Contractor shall install a single terracotta / cast-stone unit at a location selected by the Architect. All methods, materials, and workmanship required for the project shall be demonstrated. <ol> <li>The Contractor shall NOT proceed with demolition and replacement until mock up is approved by Architect.</li> <li>Retain mock-ups during construction as the standard for judging complete work.</li> <li>Incorporate approved mock up into the finished work as directed by the Architect.</li> </ol> </li> <li>The Contractor shall prepare up to three additional mock-ups without further compensation.</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>The Contractor shall inspect terra-cotta / cast stone immediately upon delivery to site. The Contractor shall reject terra-cotta / cast stone units damaged in transit, or that fail to meet specifications and quality of samples, and shall notify the manufacturer in writing. Rejected units should be stored off-site or returned to manufacturer.</li> <li>Terra-cotta / cast-stone units shall be stored on pallets or dunnage in an area away from general construction operations to avoid damage by other trades. Units shall be stored according to sequence of installation to avoid unnecessary handling of terra-cotta / cast stone. <ol> <li>Units shall stay in their original packing material until ready for use. Crates shall not be stacked and shall remain in an upright position on firm, level, and smooth surfaces. The units shall be protected from weather to prevent staining before setting.</li> </ol> </li> <li>Cementitious materials shall be stored off the ground in a clean, dry location. The Contractor shall prevent contamination of materials likely to cause staining and other defects, and shall remove materials that are damaged or otherwise unsuitable for use from the job site.</li> <li>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 Owner prior to the delivery of materials.</li> </ol>

SEQUENCING AND SCHEDULING
<ol type="A"> <li>The Contractor shall furnish terra-cotta / cast stone manufacturer with schedule of pieces to be manufactured and an installation sequence so that terra-cotta / cast stone may be produced in the variety and quantity needed to match the installation sequence. The Contractor shall provide: <ol> <li>A photograph or isometric sketch showing the dimensions of each type of unit to be produced. Field verification of required dimensions is the responsibility of the Contractor and the terra-cotta/cast stone manufacturer.</li> <li>Elevations and a site plan showing the location of units to be replaced.</li> <li>A performance specification based on original material and location conditions.</li> <li>An installation schedule showing piece counts and time frames for installation.</li> <li>At least three (3) samples of the original material to be used for color matching and compatibility of the clay body and glaze.</li> </ol> </li> <li>Schedule should reflect other considerations such as costs, weather, structural repairs, and building use requirements.</li> </ol>

PROJECT / SITE CONDITIONS
<ol type="A"> <li>The normal temperature range for the work of this Section shall be when the air and surface temperatures are 40 degrees F and rising or less than 90 degrees F and falling. When temperatures are expected to fall outside this range, the Contractor shall employ hot and cold weather procedures as published by the Masonry Institute of America.</li> <li>The Contractor is responsible for protecting existing adjacent materials and surfaces during the execution of the work and shall provide all necessary protection and follow all work procedures to avoid damage to existing material assemblies not a part of the work in this Section. The Contractor shall: <ol> <li>Prevent masonry patching materials from staining the face of masonry or other surfaces to be left exposed. Immediately remove all patching materials that come in contact with such surfaces. Protect sills, ledges, and projections from droppings.</li> <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 not be left exposed overnight or when inclement weather is predicted.</li> <li>Temporarily remove and store metal downspouts and downspout boot covers to remain during terra-cotta / cast stone work. Install temporary drainage leaders if required. Reinstall immediately upon completion of work in the immediate area.</li> <li>Protect existing scuppers and downspout outlets from damage and accumulation of mortar debris during restoration of terra-cotta/cast-stone parapets.</li> <li>Where existing masonry components are to be removed, protect adjacent masonry units and surfaces from chipping and cracking during the removal process. Where components are to be reinstalled, the Contractor shall store salvaged components in a safe location. Protect from theft and damage until reassembly.</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>The Contractor shall cover partially completed work when work is not in progress.</li> <li>The Contractor shall coordinate terra-cotta / cast stone installation with the other trades involved in exterior and interior restoration work including but not limited to masonry cleaning, sealants, and painting.</li> </ol> =PRODUCTS=

MANUFACTURERS
Follow recommendations for the selection of product suppliers as specified above. The Contractor shall submit manufacturer information to the Architect for approval.

TERRA-COTTA / CAST STONE DESIGN
<ol type="A"> <li>Terra-cotta / cast-stone units shall be outlined on Architectural Drawings with respect to exterior appearance and profile. <ol> <li>All pieces shall be manufactured for the particular installation conditions to minimize any cutting in the field. The Contractor shall adjust individual pieces to accommodate the setting sequence. (In concrete or steel frame building, the veneer or facing material should be fully and continuously supported at each floor level on shelf supports. The supports should be of adequate strength and stiffness to rigidly connect to the structural frame, steel shelf angles, or supports, and in all cases, should be located in the mortar joints. The strength of the terra-cotta / cast stone should not be unnecessarily reduced by cutting the webs to receive the steel.)</li> <li>Adjust Terra-Cotta / cast stone to accommodate relieving angles, vents, weeps, expansion joints, etc.           <li>Proper provision should be made for expansion joints, at shelf supports, over column cases, etc., to prevent the development of disruptive stresses cause by deflection, wind pressure, temperature changes, settlement and like forces.</li> <li>Properly constructed flashing should be provided.</li> <li>Reglets shall be provided to receive gutter linings and flashing when the joints cannot be used for the purpose. Reglets shall be not less than ¾-inch deep, unless otherwise specified.</li> <li>The volume changes incident to the setting and hardening of concrete, and the variations in volume of concrete due to humidity and temperature conditions require provisions to allow free movement of the supporting frame and make it undesirable to completely fill a facing applied to a concrete structure.</li> </ol> </li> </ol> </li> </ol>

TERRA-COTTA PROPERTIES
<ol type="A"> <li>Surface Features: Match color, texture, shape, size, profile, and other characteristics of existing original units.</li> <li>Terra-cotta units shall conform to the physical requirements listed below as preformed in accordance with ASTM Specifications. <ol> <li>Compressive Strength – ASTM C67</li> <li>Absorption (5 hour boil) – ASTM C67</li> <li>Saturation Coefficient – ASTM C67</li> <li>Crazing – ASTM C126</li> </ol> </li> <li>Unit Sizes: <ol> <li>As indicated on approved shop drawings.</li> <li>Size partial units with diamond-tipped, water-cooled blade.</li> <li>Dimension for setting with uniform joint width to match the existing or as otherwise approved by the Architect.</li> <li>Face Dimension Tolerances: Length and width of exposed face of each unit not to vary more than 1/16 inch over or under the dimensions specified on approved shop drawings.</li> <li>Warpage Tolerances: Exposed face of each unit not to vary from the true plane by more than 0.005 inch per inch of length.</li> </ol> </li> <li>Chipping: <ol> <li>Location, depth and diameter of chip on an exposed face or edge not to exceed ¼ inch from edges and ? inch from corners.</li> <li>Maximum percentage of chipped units permissible per crate or pallet not to exceed 10% of content.</li> <li>Total number of chipped units not to exceed 10% of replacement quantity.</li> </ol> </li> <li>Properties of Finish: In accordance with ASTM C126, finished faces shall be free from crazing, blisters, pinholes, crawling, staining, or other imperfections detracting from the appearance of the unit when viewed from a normal viewing distance or a distance of 15 feet. Finish is to match the approved sample.</li> </ol>

CAST STONE PROPERTIES
<ol type="A"> <li>Cast stone to match existing terra-cotta cornice trim shall be fabricated using Portland cement, aggregates, and pigments as required. Replacement cast stone shall meet the following requirements: <ol> <li>Compressive strength: 6,500 psi minimum at 28 days in accordance with ASTM C 1194.</li> <li>Absorption: 6% maximum at 28 days in accordance with ASTM C 1195.</li> </ol> </li> <li>Cast stone materials: <ol> <li>Portland Cement: ASTM C 150, Type I, gray or white as required to match existing.</li> <li>Aggregate: Well-graded and washed sands and gravel meeting ASTM C 33.</li> <li>Pigments: Inorganic, lime-proof, and non-fading mineral pigments.</li> <li>Reinforcing Steel (where required): New billet steel bars ASTM A 615, Grade 40 or 60, epoxy coated in accordance with ASTM D 3963.</li> </ol> </li> <li>Fabrication: <ol> <li>Fabricate new cast-stone units with a minimum wall thickness of 1 inch and partitions of such thickness and so spaced as to provide maximum strength and reinforcement. Each piece shall be provided with the necessary anchor holes or slots and hand holes, formed so as to properly engage the anchor system to the substrate below.</li> <li>Fabricate new cast-stone units to exactly match the dimensions, profiles, and surface texture of the existing units. Exterior faces shall be plumb, straight, and level. Molded edges shall be straight and crisp.</li> </ol> </li> </ol>

ACCESSORIES
<ol type="A"> <li>Anchors: Stainless steel, ANSI A167, type 304 or type 316, ½-inch-diameter round stock or square bars of equal cross section.</li> <li>Dowels: Threaded stainless steel, ANSI A167, type 304, ¼-inch minimum diameter, by length required.</li> </ol>

REPLACEMENT AND SUBSTITUTE MATERIALS:
<ol type="A"> <li>It is generally preferred to retain as much of the original fabric as possible and to replicate replacement units as closely as possible to match the original. For extensive projects, where limitations in supply (especially since most terra-cotta requires custom replication), expense, and length of time to manufacture and install new units may hinder repairs, compatible substitute materials may be used.</li> <li>Substitute materials require evaluation of use and type, and should be sampled to find the material that is compatible in material properties, weight, and finish, and meets the approval of the Architect. Substitute materials for terra-cotta units include: <ol> <li>Stone. Although stone can be a suitable replacement, is durable, and can be finished to match the terra-cotta units, it is a heavier material. The increased weight can cause additional stress to the building.</li> <li>Fiberglass. A viable alternative for elaborate ornamentation that has to be duplicated. Drawbacks in using fiberglass replacement are color compatibility, fire code violations, and poor weathering and aging.</li> <li>Precast Concrete Units. Precast concrete, as with fiberglass, can easily be used to replicate elaborate ornamentation in a modular fashion. They can also be cast hollow, use lightweight aggregate, and be made to accommodate metal anchoring as needed. Concrete can be colored or tinted to match the original material with excellent results; it is cost effective, and once production is in process, it can be produced quickly. Clear masonry coatings are preferred on the weather face of the precast concrete units for visual compatibility, to prevent moisture absorption, to obtain proper reflectivity, and to prevent weathering.</li> </ol> </li> </ol> =EXECUTION=

GENERAL
<ol type="A"> <li>Project-specific specifications are required for all terra-cotta work contained herein. As material and methods of construction vary greatly, each building must be evaluated, and work scheduled accordingly. The Contractor shall submit schedules, including methods and materials to be used.</li> <li>Terra-cotta replacement shall use techniques, methods, and materials as similar as possible to those of the original. Work should be sequenced not only to assure the stability of the structure and protection of personnel during the work, but also to address a sensible order of construction to integrate new work with existing work.</li> <li>The Contractor shall complete a survey to determine the extent and severity of the deterioration and whether the deterioration involves visual aspects of the surface terracotta,the failure of joints between units, the structural failure of the terra-cotta units, the failure of support systems, or the overall structural stability of the building façade. <ol> <li>Notation of existing general failures that contribute to terra-cotta deterioration shall be noted and should be scheduled for repair prior to completion of the work scheduled or in conjunction with terra-cotta replacements.</li> <li>Complete testing shall be conducted; the extent and type of analysis will be determined by the Architect.</li> </ol> </li> <li>The Contractor shall protect adjacent materials, installed non-masonry materials, and openings.</li> <li>Manufacturer’s instructions for mixing and installation of materials and equipment use shall be followed.</li> <li>Façade cleaning shall be completed prior to beginning replacement work.</li> <li>The Contractor shall stabilize deteriorated and loose units that are not scheduled to be removed or that cannot be easily removed. Areas where units are missing or have been removed should be protected against moisture penetration until replacement units can be installed.</li> </ol>

GENERAL PROCEDURE FOR REPLACEMENT OF TERRA-COTTA
<ol type="A"> <li>When replacing glazed architectural terra-cotta, all of the original deteriorated material should be completely removed. Half bricks or similar cosmetic replacement techniques are not recommended. <ol> <li>Remove the deteriorated units and anchoring. Anchoring must be replaced with new anchors when installing replacement units.</li> <li>Retain the original backfill.</li> </ol> </li> <li>Prepare the area to accept new mortar. Area should be free from dust, dirt, mortar, and other debris. Brush the area free of debris and dirt with a natural or nylon bristle brush. Do NOT use metal bristle brushes.</li> <li>When possible and where applicable, replacement units should be anchored in a manner similar to the original. Both structural and visual compatibility are major considerations when choosing replacement materials. <ol> <li>Replacement unit shall be fitted into the existing backfill by boring a hole or slot for the anchor and bedding the anchor and the unit itself in mortar. Terra-cotta units and their facsimiles cannot be simply mortared in place. Always use anchoring to install new units.</li> </ol> </li> <li>Mortar Joints: The procedure for pointing terra-cotta is similar to pointing masonry joints. Surfaces should be well sealed to prevent moisture penetration. Mortar should becompatible with current building conditions as well as the existing terra-cotta units. See Section 04100, Historic Mortar.</li> <li>The Contractor shall protect terra-cotta from splatter when using sealants and caulking. The units must be cleaned immediately. Generally, a barrier, such as petroleum jelly, can be applied for easy clean up.</li> </ol>

FINAL REPORT
<ol type="A"> <li>The Contractor shall revisit the site with the Architect after the new mortar has cured at least 30 days to see if desired effect has been achieved.</li> <li>Document the work and finished product with photographs taken before, during, and after completion of the work.</li> <li>The Contractor shall 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.</li> </ol>