Patching Cracks And Holes In Woodwork

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 patching cracks and small holes in woodwork.
  2. See 01100-07-S for general project guidelines to be reviewed along with this procedure. These guidelines cover the following sections:
    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)

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


  1. AWI Quality Standard: Comply with applicable requirements of the latest edition of "Architectural Woodwork Standards", published by the Architectural Woodwork Institute (, except as otherwise indicated.


  1. Performance Requirements: Submit written program for each phase of restoration process including protection of surrounding materials on building during operations. Describe in detail materials, methods and equipment to be used for each phase of restoration work.


  1. Mock-Ups: Prior to start of wood restoration work, prepare the following sample panels in building where directed by RHPO. Obtain RHPO's acceptance of visual qualities before proceeding with the work. Retain acceptable panels in undisturbed condition, suitably marked, during construction as a standard for judging completed work.
    1. Wood Repair: Prepare sample panels for each type of woodwork indicated to be patched, resurfaced, modified or replaced. Prepare mock-up panels on existing woodwork to demonstrate quality of materials and workmanship.


  1. Existing Conditions:
    1. Installer shall advise Contractor of temperature and humidity requirements for woodwork installation areas. Do not install woodwork until required temperature and relative humidity have been stabilized and will be maintained in installation areas.
    2. Maintain temperature and humidity in installation area as required to maintain moisture content of installed woodwork within a 1.0 percent tolerance of optimum moisture content, from date of installation through remainder of construction period. The fabricator of woodwork shall determine optimum moisture content and required temperature and humidity conditions.
    3. Determine that surfaces to which finishes are to be applied are even, smooth, sound, clean, dry and free from defects affecting proper application. Correct or report defective surfaces to Contracting Officer.



  1. Patching Materials:
    1. Wood Filler: Standard filler manufactured specifically for restorative patching of woodwork.
      1. Tint filler to match existing woodwork.
    2. Sandpaper: No. 3/0 or No. 5/0 garnet paper.
  2. Replacement Wood: Match species, grade, grain pattern, and other special characteristics of existing woodwork.



  1. Remove all minor surface imperfections such as scratches, dents, etc., by rubbing surface with a fine grit sandpaper.
  2. Patch all holes and cracks in woodwork up to 1/16 (one sixteenth) inch across with wood filler tinted to match existing wood.
  3. Carefully hand rub filled area with a fine grit sandpaper to match surface characteristics of adjacent woodwork.
  4. Touch-up patch during finishing so that color and other appearance characteristics of filled area match the >finish of adjacent woodwork. See 06400-05-R, 06400-06-R, and 06400-10-R for guidance on refinishing.
  5. Patch holes and cracks in woodwork 1/4 (one quarter) inch and greater across and woodwork damaged from hardware changes with wood plugs or wood patches or as directed by manufacturer.
  6. Rout out hole or crack woodwork to receive plus or patch materials. Veneer-type patches shall be comparable to the thickness of the surrounding intact veneer and historically 1/16 (one sixteenth) to 1/20 (one twentieth) inch thick, referring to the thickness of the veneer.
  7. All repair plugs and patches in wood with a transparent finish shall have grain aligned.


  1. Upon completion of this work, all floors, walls, and other adjacent surfaces that are stained, marred, or otherwise damaged by work under this section shall be cleaned and repaired and all work and the adjacent areas shall be left in a clean and perfect condition.
  2. All completed work shall be adequately protected from damage by subsequent building operations and effects of weather. Protection shall be by methods recommended by the manufacturer of installed materials and as approved by the RHPO.
  3. Repair damaged and defective woodwork wherever possible to eliminate defects functionally and visually; where not possible to repair properly, replace woodwork. Adjust joinery for uniform appearance.
  4. Clean woodwork: Dust and damp wipe woodwork with a soft cloth dampened in clean water; dry rub with soft cloth to maintain the polish, rubbing along the grain of the wood.
  5. Stain and Spot Removal:
    1. Stains may be cleaned by prompt damp wiping with cloth dampened in clear water or rubbing with cloth dampened in solvent. Dry the wood with a soft cloth.
    2. White spots may be removed by rubbing them with a small amount of linseed oil.