Replacing Damaged Encaustic Floor Tiles

Technical Procedures Disclaimer

Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.


We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. 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.



  1. This procedure includes guidance on removing and replacing damaged or deteriorated encaustic floor tiles. Replacement may involve using tile salvaged from other locations or reproducing tile to match the existing tile.
  2. For additional information on the characteristics, uses and the production/reproduction process of encaustic tiles, see 09310-02-S.
  3. See 01100-07-S for general project guidelines to be used along with this procedure. These guidelines cover the following sections:
    1. Historic Structures Precautions
    2. Submittals
    3. Quality Assurance
    4. Delivery, Storage and Handling
    5. Project/Site Conditions
    6. Sequencing and Scheduling
    7. General Protection (Surface and Surrounding)

These guidelines should be reviewed prior to performing this procedure and should be followed along with recommendations from the Regional Historic Preservation Officer (RHPO).


  1. The Tile Council of North America, Inc. (TCNA),
  2. American National Standards Institute, Inc. (ANSI),


  1. Performance Requirements: Completed encaustic tile installation to be within tolerances as follows:
    1. Variation from a true plane not to exceed 3/16" in 10'-0", any direction, but not more than 3/8" for total length.
    2. Variation in offset of edge-to-edge alignment of adjoining tile not to exceed 1/32".


  1. Product Data: Submit manufacturer's technical information and installation instructions for all materials required, except bulk materials. Include certifications and other data as may be required to show compliance with this specification.


  1. Manufacturing Standards:
    1. When using setting and grouting materials manufactured under TCNA license, include identification and formula number on each container.
    2. Provide materials obtained from only one source for each type to minimize variations in appearance and quality.
  2. Mock-Ups: A representative sample area as indicated of 100 square feet will be restored. Obtain acceptance of the sample area before proceeding with the remainder of the restoration. Maintain sample area in its accepted condition until acceptance of completed work.


  1. Packing and Shipping: Deliver packaged materials and store in original containers with seals unbroken andlabels intact until time of use, in accord with directions of manufacturer.


  1. Environmental Requirements: Maintain a temperature of not less than 50 degrees F. during tile installation and for 7 days after completion.



  1. Tile: Encaustic tile to match existing in color, shape and size. Existing tile from other areas of the building may be used after cleaning and evaluation for soundness and compatibility.
  2. Mortar and Grout:
    1. Latex-Portland Cement Mortar: Latex modified portland cement thin-set mortar complying with ANSI A118.4.
    2. Latex-Portland Cement Grout: Proprietary compound composed of portland cement with latex additive for a more flexible and less permeable grout. Color to match existing grout.
    3. Epoxy Patch Compound: Two component resin and hardener complying with ANSI A118.3. Colors to match existing tiles.
    4. Epoxy Mortar: Two-component epoxy resin and hardener; ANSI A118.3.
    5. Water: Clean and free of deleterious materials which would impair strength, bond or appearance.



  1. Examine the substrate and the conditions under which tile is to be installed. Do not proceed with the work until unsatisfactory conditions have been corrected, which includes a level and even bedding for new work.


  1. Surface Preparation:
    1. Areas of existing tile indicated to be removed and reused shall be carefully loosened from the substrate, cleaned and stored for use as replacement tile.
    2. Cracked, crumbled or shattered tile shall be carefully removed in such a manner so as not to damage in any way nor to dislocated any adjacent tiles.
    3. Pitted tile shall be carefully repaired with epoxy patch compound to produce a smooth even surface and to completely fill existing surface voids.


  1. Before installing new tile, carefully examine exposed substrate.
    1. If substrate is found to be solid and a sound surface for new work, install new tile with epoxy mortar.
    2. If substrate is NOT found to provide a sound surface for the new work, provide applicable tile installation method for substrate and performance as described below and complying with TCNA "Handbook for Ceramic, Glass, and Stone Tile Installation".
  2. Install New Tiles:
    1. Use a Latex-Portland Cement Mortar: Latex modified portland cement thin-set mortar; ANSI A118.4.
    2. Joint Pattern: Unless otherwise indicated, lay tile in exact configuration as the removed tile. Align joints and provide uniform joint widths.
    3. Colors and Existing Pattern: When new replacement tile or tiles are installed, the colors and locations of the tiles must exactly duplicate and match the removed original(s).
    4. Coverage: Extend tile work into recesses and under equipment and fixtures, to form a complete covering without interruptions, except as otherwise indicated. Terminate work neatly at obstructions, edges and corners without disruption of pattern or joint alignment, and use applicable trim and special shapes as required.
    5. Fitting: Accurately form intersections and returns, and use applicable special shapes as required. Perform cutting of tile without marring visible surfaces. Carefully grind cut edges of tile abutting trim, finish or built-in items for straight, aligned joints. Fit tile closely to electrical outlets, piping and fixtures so that plates, collars or covers overlap tile.
    6. Setting Beds: Provide applicable setting bed types as required. Handle and apply proprietary mortar materials complying with instructions of the manufacturer.
    7. Setting Tile: Set encaustic tile in place, and tamp level and even with adjacent tile and within required tolerances. Use appropriate spacers to obtain a straight and uniform joint.
    8. Grouting: Provide applicable grout types as required. Handle and apply grout complying with instructions of manufacturer. Start grouting after the setting bed mortar has cured and tiles are firm and secure in-place.


  1. Clean grout and setting materials from face of tile while materials are workable. Leave tile face clean and free of all foreign matter. DO NOT USE ACID OR CAUSTIC MATERIALS TO CLEAN TILE.
  2. Leave restored areas clean and free of cracked, chipped, broken, unbonded or otherwise defective tile.


  1. Install a protective covering to protect the floor during the construction period.
  2. Prohibit all foot and wheel traffic from using tiled floors for at least 3 days, preferably 7 days.
  3. Before final inspection, remove protective covering clean and rinse all tile surfaces. Wash tile surfaces clean.