General Guidelines For The Fabrication And Installation Of 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.

PREFACE: Windows are an important design element contributing to a building s architectural character. For historic buildings, state historic preservation officers generally apply the Secretary of Interior Standards for Rehabilitation which require that original material be repaired and retained where possible. Condition surveys are typically required to determine if windows are too deteriorated to save, before replacements will be considered. Replacement windows should match the color, size and configuration of the original windows and the material.


  1. This procedure includes general information relating to the fabrication and installation of wood windows andincludes the following window types:
    1. Double-Hung Window Units.
    2. Casement Window Units.
    3. Decorative Window Units.
    4. Hopper Window Units.
    5. Non-Operative (Fixed) Window Units.
    6. Single-Hung Window Units.
  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)
    9. 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. American Society for Testing and Materials (ASTM),
    100 Barr Drive, West Conshohocken, PA 19428
  2. American National Standards Institute, Inc. (ANSI),
    1430 Broadway, New York, NY 10018.
    Flat Glass Marketing Association (FGMA),
    National Wood Window and Door Association (NWWDA),


  1. Performance Grade Classification: Provide wood windows that comply with requirements of NWWDA I.S. 2 for performance grade 40.
  2. Performance Grade Classification: Provide wood windows that comply with requirements of NWWDA I.S. 2 for performance grade 60.
  3. Standards: Performance requirements for structural performance, air infiltration, and water penetration for wood windows are those specified in NWWDA I.S."Industry Standard for Wood Window Units".
  4. Testing: Manufacturer's stock units of each grade of required wood window shall have been tested by a recognized testing laboratory or agency, in accordance with ASTM E330 for structural performance. Test samples shall comply with requirements in NWWDA I.S. 2 for test sample sizes and methods.
  5. Performance Requirements (Grade 60 Windows): Each required window unit shall comply with the following performance requirements:
    1. Air Infiltration: Not more than 0.10 cfm per sq. ft. of overall frame area at an inward test pressure of 1.57 lbf per sq. ft.
    2. Water Penetration: No water penetration as defined in the test method at an inward test pressure of 6.24 lbf per sq. ft.
    3. Structural Performance: No glass breakage, damage to hardware, or permanent deformation that would impair operation of the unit or residual deflection greater than 0.4 percent of the span at a positive (inward) and negative (outward) test pressure of 60 lbf per sq. ft.
    4. Forced Entry Resistance: Windows shall comply with requirements for Grade 40 level of resistance to forced entry when tested in accordance with ASTM F588.


  1. Product Data: Submit product data for each type of wood window specified, including standard construction details, dimensions of individual components, profiles, finishes, hardware, and accessories.
  2. Shop Drawings: Submit shop drawings for each type of window specified, including 1/4-inch scale wall elevations, typical unit elevations at 3/4-inch scale, glazing details, and fill-size details of typical composite members.


  1. Wood Window Standard: Comply with provisions of NWWDA I.S. 2 for standards of performance and fabrication workmanship for wood windows.
  2. Glazing Standards: Comply with recommendations of the Flat Glass Marketing Association (FGMA) "Glazing Manual" and "Sealant Manual" except where more stringent requirements are indicated. Refer to those publications for definitions of glass and glazing terms not otherwise defined in this section or referenced standards.
  3. Safety Glass Standard: Where safety glass is indicated or required by authorities having jurisdiction, provide the type of products indicated which comply with ANSI Z97.1 and testing requirements of 16 CFR Part 1201 for category II materials.
  4. Insulating Glass Certification Program: Provide insulating glass units permanently marked either on spacers at least one component pane of units with the appropriate certification label of inspecting and testing organization indicated below.
    1. Insulating Glass Certification Council (IGCC)
    2. Associated Laboratories, Inc. (ALI)
  5. Single Source Responsibility:Provide wood windows produced by a single fabricator who is capable of indicating prior successful production of units similar to those required.


  1. Field Measurements:
    1. Check actual window openings in construction work by accurate field measurement before fabrication of custom window units. Show recorded measurements on final shop drawings.
    2. Coordinate fabrication with construction progress to avoid delay. Where necessary, proceed with fabrication without measurements, and coordinate tolerances to ensure proper fit of window units.


  1. Submit a written warranty signed by the Manufacturer, agreeing to repair or replace wood window units that fail in materials or workmanship within the specified warranty period.
    1. Failures include, but are not limited to, structural failures, including excessive deflection, excessive leakage, air infiltration, failure of weatherstripping, faulty operation of window sash or hardware, and deterioration of metals, finishes, and other materials beyond normal weathering.
    2. Warranty period for wood windows is 3 years after the date of substantial completion.
    3. This warranty shall be in addition to and not a limitation of other rights the Government may have against the Contractor under the Contract Documents.



  1. Pella Corp.
    102 Main Street
    Pella, IA 0219
  2. Andersen Corporation
    100 Fourth Avenue North
    Bayport, MN 55003


  1. General: Comply with requirements of NWWDA I.S. 2.
  2. Wood: Clear Ponderosa Pine or other suitable fine-grained lumber that has been kiln-dried to a moisture content of 6 to 12 percent at time of fabrication and is free of visible finger-joints, blue stain, knots, pitch-pockets and surface checks larger than 1/8-inch deep by 2-inches wide.
    1. Lumber shall be water-repellent preservative treated after machining in accordance with NWWDA I.S. 4.
  3. Aluminum Cladding: Provide manufacturer's standard aluminum formed sheet or extruded cladding mechanically bonded to exterior wood sash and frame members.
    1. Trim members: Aluminum clad wood trim.
    2. Finish: Provide factory-applied baked-on enamel finish.
    3. Color: Custom color as selected by the Architect from the manufacturer's standard color range.
  4. Anchors, Clips, and Accessories: Fabricate anchors, clips and window accessories of aluminum, non-magnetic stainless steel, or hot-dip zinc coated steel complying with ASTM A123; provide strength sufficient to withstand design pressure indicated.
  5. Fasteners: Comply with NWWDA I.S. 2 for fabrication and with manufacturer's recommendations and standard industry practices for type and size of installation fasteners.
    1. Use zinc-coated or nonferrous nails and screws for window fabrication and installation.
    2. Use brass screws for hardware and accessory installation.
  6. Hardware: Provide the manufacturer's standard hardware, necessary to properly operate, tightly close, and securely lock windows. Do not use aluminum in frictional contact with other metals.
    1. Provide solid bronze hardware, with plated steel orbrass/bronze operating bars and rods.
  7. Compression Weatherstripping: Provide compressible weatherstripping, designed for permanently resilient sealing under bumper or wiper action, completely concealed when sash is closed.
  8. Glass and Glazing Materials: Provide the manufacturer's standard clear sealed insulating safety glazing material that complies with ANSI Z97.1.
    1. Insulating glass unit shall have metal spacers, sealed between the panes, behind each muntin bar.
  9. Glazing Seal: Provide the manufacturer's standard extruded vinyl or butyl glazing gasket providing weathertight seal.
  10. Sliding Weatherstripping: Provide woven pile weatherstripping of polypropylene, wool, or nylon pile, with resin-impregnated backing fabric, and aluminum backing strip; comply with AAMA 701.2.


  1. General: Comply with minimum operating requirements of NWWDA I.S. 2.
  2. Casement Windows: Provide units containing side-hinged swing-out sash, with the following equipment and hardware:
    1. Hook or cam-type latch and lever, for operation without screen removal.
    2. For sash more than 48 inches high, provide 3 extension hinges and 2-point latching mechanism.
  3. Double-Hung Windows: Provide units containing 2 balanced, vertically-sliding sash with the following equipment and hardware. 2 pair concealed counterbalancing mechanism.
    1. Latch at meeting rail.
    2. Lift handle on the lower rail.
  4. Hopper Windows: Provide units containing bottom-hinged (hopper) sash with the following equipment and hardware:
    1. 2 balance support arms and pivots with friction shoes.
    2. Cam latch or other latching hardware with lever handle or pull. Provide latch with eye for pole operation for operable sash located more than 6 feet above the floor.


  1. General: Except to the extent that more stringent requirements are indicated, provide the manufacturer's standard fabrication of units. Comply with indicated standards. Include a complete system for assembly of components and anchorage of window units.
    1. Comply with requirements of referenced standards for moisture content of lumber at time of fabrication and for relative humidity conditions in the installation areas.
  2. Fabricate windows to produce units that are re-glazable without dismantling sash framing. Provide openings and mortises precut, where possible, to receive hardware and other items.
  3. Each window unit includes sash, frame, stops, sill (including undersill or nosing), and moldings, integral mullions and muntins, hardware, and accessories
  4. Provide weatherstripping at perimeter of each operating sash.
    1. Provide weatherstripping at perimeter of each operating sash.
      1. For double/single-hung sash, provide weatherstripping only at horizontal rails of operable sash.
    2. Provide glazing stops, nailed or snap-on, coordinated with glass selection and glazing system indicated
    3. Preglazed Window Units: Preglaze window units at he shop before delivery.
  5. Complete fabrication, assembly, finishing, hardware application, and other work before shipment to the project site, to the maximum extent possible. Disassemble components only as necessary for shipment and installation. Where necessary for fitting at site, provide ample allowance for scribing, trimming, and fitting.
  6. Wood Finish: Provide the following finish on exposed wood in units:
    1. 1Shop-Primed Units: Provide the fabricator's standard shop prime coat on exterior wood surfaces only.


  1. Inspect openings before beginning installation. Verify that the rough or masonry opening is correct and the sill plate is level. Do not proceed with installation of window units until unsatisfactory conditions have beencorrected.
    1. Masonry surfaces shall be visibly dry, and free of excess mortar, sand, and other construction debris.
    2. Wood frame walls shall be dry, clean, sound and well-nailed, free of voids, and without offsets at joints. Ensure that nail heads are driven flush with surfaces in the opening and within 3 inches of the opening.


  1. Comply with manufacturer's instructions and recommendations for installation of window units, hardware, operators, accessories, and other window components.
  2. Set units plumb, level, true to line, without warp or rack of frames or sash. Provide proper support and anchor securely in place.
  3. Set sill members in a bed of compound or with joint fillers or gaskets as indicated, to provide weathertight construction. Coordinate window installation with wall flashings and other built-in components.


  1. Adjust operating sash and hardware to provide a tight fit at contact points and weatherstripping, and to provide smooth operation and a weathertight closure. Lubricate hardware and moving parts.
  2. Clean interior and exterior surfaces promptly after installation of windows. Take care to avoid damage to protective coatings and finishes. Remove excess glazing and sealants, dirt, and other substances.
  3. Clean glass of preglazed window units promptly after installation. Wash and polish glass on both faces not more than 4 days prior to date scheduled for final inspection. Comply with manufacturer's recommendations for final cleaning and maintenance.
  4. Remove and replace glass that is broken, chipped, cracked, abraded or damaged in other ways during construction period, including natural causes, accidents, and vandalism.


  1. Institute and maintain protection and other precautions required through remainder of construction period to ensure that, except for normal weathering, window units
  2. will be without damage or deterioration at the time of substantial completion.