Rehabilitating Wood Windows

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 for the rehabilitation of wood windows. Outlined are the steps one might go through to complete repairs. Each step is cross-referenced to one or more procedures which covers the particular problem. The cross-referenced procedures should be reviewed prior to beginning window repairs and should be followed along with recommendations from the Regional Historic Preservation Officer (RHPO).
  2. The steps in the repair of deteriorated sash include but are not limited to the following:
    1. Examination, survey and condition assessment of windows.
    2. Removal of existing sash, trim, etc.
    3. Repair of deteriorated wood through the use of epoxies, dutchmen and/or the replacement with new wood to match the existing appearance.
    4. Painting/refinishing sash and trim.
    5. Installation of repaired sash.
  3. 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 before performing this procedure and should be followed, when applicable, along with recommendations from the RHPO.
  4. For general information on the repair of wood windows see 08610-01-S, "Preservation Briefs: 9 - The Repair of Historic Wooden Windows."


  1. Shop drawings for each type of window, including 1/4-inch scale wall elevations, typical unit elevations at 3/4- inch scale, glazing details, and full-size details of typical composite members, include window rehabilitation, wood and hardware replacement, reglazing details and weatherstripping.
  2. The RHPO reserves the right to require additional samples that show fabrication techniques and construction and design of hardware and accessories.


  1. Rehabilitation of windows shall be completed before doing any interior restoration/rehabilitation work to insure weather-tight integrity of interior spaces.



NOTE: See specific procedures for materials and equipment requirements, and their manufacturers and sources.



  1. Conduct a window-by-window survey to determine existing conditions and identify the specific work needs of each window.
  2. For each window type, the survey should include color photographs which show design details for comparison to new work, and existing conditions.
    1. Full frame views, both interior and exterior.
    2. Close-up views of typical details, both interior and exterior.


  1. Carefully remove window stops, sash and trim as required. Remove only those features which cannot be repaired on- site. All disassembled parts should be indelibly marked or stamped on hidden parts so they can be returned to their exact location.
    1. See 06440-03-R, "Closing Open Joints in Wood Wall Ornament"
  2. Replace rotted window sills as required.
    1. See 08610-04-R, "Replacing a Wood Window Sill"
  3. Repair, replace, or rebuild all rotted or deteriorated wood features. These can include but are not limited to stiles, rails, muntins, joints, frame, trim. New work shall match existing profiles or shapes in every respect and shall be flush with existing adjacent surfaces.
    1. See 06300-01-R, "Epoxy Repair for Deterioration and Decay in Wooden Members"
    2. See 08611-01-R, "Sealing Leaky Wood Double-Hung Windows"
    3. See 06440-01-R, "Repairing Cracks and Checks in Wood Wall Ornament
    4. See 06440-03-R, "Closing Open Joints in Wood Wall Ornament"
    5. See 06440-04-R, "Repairing Scratches, Gouges and Dents in Wood Wall Ornament"
    6. See 09560-03-R, "Dutchman Repair of Wood Floor Boards"
  4. Remove paint from both interior (where applicable) and exterior surfaces.
    1. See 06400-07-R, "Chemically Removing Paint From Wood Features"
    2. See 06400-02-S, "Supplemental Guidelines for Removing Paint from Interior and Exterior Wood Surfaces"
    3. See 06400-09-R, "Removing Paint From Wood Features Using Thermal Methods"
  5. Remove all deteriorated glazing putty and broken glass. Replace glass and reglaze with a flexible elastomeric glazing compound. Clean the existing historic glass. See 08800-01-R, "Replacing Broken Glass in Wood and Metal Windows"
  6. Reinstall windows. Inspect pull chains and weights at all double hung windows and adjust, clean or replace as required to ensure proper operation. Lubricate all working parts to assure smooth operation.
    1. See 08760-01-R, "Repairing Double-Hung Window Sash Weights and Cords/Chains"
    2. See 08712-01-R, "Resetting a Hinge Mortise"
  7. Provide weatherstripping as required.
    1. See 08500-01-R, "Installing Weatherstripping on Metal Double-Hung Windows"
  8. Refinish both interior and exterior sides of sash, frame and trim with appropriate paint, stain or natural finish as specified.
    1. See 06300-01-S, "Primers and Paints for Wood"
    2. See 06300-02-R, "Surface Preparation for Painting Wood"
    3. See 06400-10-R, "Refinishing Interior Wood"
    4. See 06310-01-S, "Preparing a Non-toxic Water-repellent Preservative"
    5. See 06310-01-P, "Applying a Water-repellent Preservative to Wood"
    6. See 09900-07-S, "General Guidelines for Painting Exterior and Interior Surfaces"
    7. See 06300-03-R, "Applying a Semi-Transparent or Opaque Stain to Wood"
  9. Hardware:
    1. All window hardware shall be removed, marked for proper room number and location, boxed or packaged, and collected in a central location for the Contractor who shall polish all the hardware before reinstallation.
    2. All hardware to be removed before paint stripping, cleaned to bare metal and repaired to its original condition.
    3. Where hardware is missing or damaged, provide new hardware of same design and material as original hardware.


  1. Begin and maintain protection and other precautions required through the remainder of construction period to ensure that newly rehabilitated window units will not be damaged throughout the remainder of any restoration or rehabilitation work.