Wood Window Specifications

Museum-quality window restoration for your house

The following exterior wood window restoration specifications reflect the technical and performance standards Historic New England expects from contractors working on our museum properties.

They are an example of the range of potential requirements you may wish to consider when having your wood windows restored. Not every aspect of these specifications should be required or would be suitable for a private residence.


Part I: General

A. Work of this Section, as shown or specified, shall be in accordance with the requirements of the Contract Documents.

A. General: Provide all labor, materials, equipment, and services required to complete wood window restoration as specified herein, and required by existing conditions and authorities having jurisdiction.
B. Wood window restoration may include, but is not limited to, the following:
1. Restore damaged and inoperable wood window sash while maintaining current profiles.
2. Restore existing and provide new window balance hardware at all operable sash to accommodate use.
3. Replace all broken and unsound sash cord.
4. Restore existing window hardware and provide new in kind window hardware where existing hardware is missing or is too damaged or deteriorated to be restorable.
5. Restore all window trim disturbed for work of this Section to sound condition and existing appearance.
6. Paint and finish all wood elements as necessary to match original finishes.
7. Glue or replace cracked, broken or missing glass.
8. Remove all deteriorated putty and replace with new.
9. Consolidate and repair deteriorated wood sills, framing members and sash rails and stiles.
10. Replace all broken or deteriorated parting strips.
11. Reinstall repaired window sash.
12. Clean all glass.
C. Intent: It is the specific intent of this Section that repairs will maximize the retention of historic fabric while making the windows weather resistant for long-term use and serviceable for cyclical maintenance.

A. Craftspeople: Wood window restoration shall be carried out by a steady crew of skilled craftspeople who are thoroughly experienced with materials and methods specified.
B. Laws, Codes, and Regulations: All work of this Section shall comply with all applicable federal, state, and local laws, codes, and regulations.
C. Knowledge of Site: Bidders shall visit site prior to bid and carefully examine Project scope and conditions that may affect proper execution of work of this Section and determine or verify dimensions and quantities. Contractor’s submission of bid shall be acknowledgment that s/he is thoroughly familiar with Project scope and site conditions.
D. Access for Inspection, Documentation and Approvals: Provide Preservation Manager access on a regular basis to all locations on which mockups are being carried out, on which work is ongoing, and where work has been completed to allow for inspections, documentation and approvals. Provide means of access and safety precautions required to facilitate inspections and approvals.

A. General: Submit the following in compliance with the requirements of the Conditions of the Contract. Revise and resubmit each item as required to obtain Preservation Manager’s approval.
B. Product Literature: Manufacturer’s published technical data for each product to be used in work of this Section including recommendations for application and use, test reports and certificates verifying that product complies with specified requirements, and Material Safety Data Sheets (MSDS).
C. Documentation: Documentation in the form of high-resolution (1 megabyte minimum) JPEG images on CDROM showing the existing condition of all elements of windows to be removed for work of this Section, all elements adjacent to elements that are to be removed, and all other window elements that will be in any way affected by work of this Section. Show overall trim and details of all damage or deterioration that might be attributed to damage resulting from work of this Section.
D. Wood Treatment Data: Chemical treatment manufacturer’s instructions for handling, storage, installation, and finishing treated materials if applicable.

A. Bidders shall visit the site beforehand to make themselves familiar with specific conditions relating to this Section.
B. Comply with relevant ASTM standards for all materials.
C. All Subcontractors are bound by the same requirements as the Contractor. Subcontractors shall not begin work unless approved by the Preservation Manager.

A. Deliver, store, and handle all products and materials to prevent damage, deterioration, or degradation and intrusion of foreign material.
B. Discard and remove from site deteriorated or contaminated materials and products that have exceeded their expiration dates. Replace with fresh materials.

A. Protection of Persons: Take all necessary precautions to protect all persons, whether engaged in work of this Section or not, from all hazards of any kind associated with the work of this Section.
B. Protection of Window Opening: After removal of the sash, all window openings shall be closed with plywood or acrylic panels fitted to each individual window and secured by non-destructive anchoring system. The panel shall be adequately weathertight and not permit any moisture to enter the building.
C. Protection of Building: Protect building elements and finishes from damage or deterioration caused by work of this Section. Repair any damage to materials or finishes to Preservation Manager’s satisfaction at no additional cost.
1. Take all necessary precautions to prevent fire and spread of fire.
2. Take all necessary precautions to protect building elements and finishes from damage by precipitation during work of this Section. Protect openings at all times. Repair or replace to Preservation Manager’s satisfaction all building elements and materials damaged by weather resulting from window openings that did not sufficiently exclude weather at no additional cost.
D. Coordination: Coordinate work of this Section with work specified in other sections to ensure proper completion of the Work. Every effort shall be made to accommodate the needs of Historic New England staff in relation to scheduling.

A. General: Perform work only when temperature of products being used, temperatures of existing and new materials, and air temperature and humidity comply with product manufacturer’s requirements and requirements of this Section. In case of conflict, the most stringent requirements shall govern.
B. Use of Epoxy Resins: Mix and apply epoxy resins only when temperatures are between 50 deg F and 80 deg F.

A. General: Perform all work that disturbs lead-containing paint (LCP), handle all material that involves lead-containing paint, and transport and dispose of all lead-containing paint and residue in compliance with all applicable federal, state, and local laws and regulations for identification, removal, labeling, handling, containerization, transportation, and disposal of lead-containing material including, but not limited to, those referenced herein.
B. U.S. Department of Labor OSHA Regulations: Including but not limited to: Title 29, Code of Federal Regulations (CFR) Section 1926.62: “Lead Exposure in Construction” and Title 29, CFR Section 1910.1200: “Hazard Communication Standard.”
C. U.S. Environmental Protection Agency (USEPA) Regulations: Including but not limited to: Title 40 CFR Part 262: “Standards Applicable to Generators of Hazardous Waste” and Part 263: “Standards Applicable to Transporters of Hazardous Waste.”
D. U.S. Department of Transportation (USDOT) Regulations: Including but not limited to: 49 CFR Parts 172, 173, 174, 175, 177, 178, 179, and 180.

41241_-_471_x_360Part 2: Products

A. Grade and Quality: Materials shall conform to requirements of this Section and shall be new, free from defects, and of recent manufacture.
B. Manufacturer’s Instructions: Comply with material manufacturers’ instructions for use of products (including surface preparation, mixing, applying, drying, etc.). In case of conflict with requirements of this Section, the more stringent requirements shall govern.

2.2 WOOD
A. Lumber shall be of sound stock, solid wood without finger joints or other joints within members, thoroughly seasoned, and kiln-dried to a moisture content not exceeding 8 percent.
B. Wood shall be free from defects or blemishes on surfaces exposed to view that will show after paints and finishes have been applied. Materials that do not comply with specifications for quality and grade, are in any way defective, or are otherwise not in proper condition will be rejected.
C. Wood for New Sash as necessary, Other New Elements, and Repairs of Existing Elements shall match profile and grade of existing windows in species, quality, cut, and grain pattern in kind.
D. Preservative treatment shall be used for new wood after machining.

A. Adhesive for Dutchman Repairs, Member Replacement, and Fabrication of New Sash: Epoxy resin glue designed for use with wood. Provide West System as manufactured by Gougeon Brothers, Inc., 706 Martin Street, Bay City, Michigan 48706 or approved equivalent. Provide the following materials: 105 Resin and 206 Slow Hardener or approved equivalent.
B. Adhesive for glass repair: Provide HXTAL NYL-1 Epoxy adhesive.

A. General: All fasteners for construction of new sash shall be stainless steel or nonferrous metal of appropriate size and configuration for use intended and approved by Preservation Manager.

A. General: Provide each restored window with full complement of hardware and fasteners matching that on original windows. Use salvaged, restored existing hardware insofar as possible and new hardware to match existing hardware where hardware is missing or existing hardware is damaged or deteriorated so as to be unrestorable.
1. Restored Existing Hardware: Restore all existing hardware to be reused following requirements of Article 3.11 “Restoration of Existing Historic Hardware,” below.
2. New Hardware: Provide new hardware and fasteners to match existing hardware and fasteners in all respects.
B. Sash Lifts: Restore any existing sash lifts insofar as possible and new sash lifts to match existing sash lifts in material, configuration, size, and finish where existing sash lifts are missing or damaged so as to be non-restorable.
C. Sash Locks: Restore any existing sash locks insofar as possible and new sash locks to match existing sash locks in material, configuration, size, and finish where existing sash locks are missing or damaged so as to be non-restorable.
D. Sash Pulleys: Clean, lubricate and reuse sash pulleys. Replace sash pulleys if necessary to operate the windows with sash chains.
E. Sash Cord: Replace all sash cords with minimum breaking strain capacity of 350 kg.
F. Sash Weights: Ensure that sash weights allow full operation of each sash and allow sash to be balanced at any position in which it is placed. Add weights to existing sash weights or replace existing sash weights with new heavier weights to balance heavier sash if necessary.
G. Screws for Attaching Restored Existing Hardware: Clean, salvage existing screws insofar as possible. Where screws are missing or damaged so as to be unsalvageable, provide new screws to match existing screws in material, size, and configuration.
H. Screws for Attaching Replacement Hardware: New screws matching screws in existing hardware.

A. General: Paint shall be of premium quality and match existing color exactly unless otherwise specified and shall comply with requirements of contract document. Primer shall be either oil-based or 100% acrylic and finish paint shall be 100% acrylic.
B. Glazing Putty: Putty is to be best quality pure linseed or soybean oil from manufacturer approved by Preservation Manager.

A. Non-metallic Cleaning Pads: Scotch-Brite pads, extra fine, manufactured by 3M Co., or approved equal.
B. Wadding Cloth: “Never-Dull Magic Wadding Polish,” manufactured by The George Basch Co., Inc., 19 Hanse Avenue, P.O. Box 188, Freeport, NY 11520, or approved equal.
C. Paste Wax for Cold Application: White or clear paste wax, mixtures of microcrystalline wax, carnuba wax, and mild solvent, in paste form, such as Trewax clear, or Butcher’s Bowling Alley Paste Wax available from White Diamond Co., Marlboro, MA. Do not use emulsion-type waxes or amber-tinted waxes.
D. Thinner: Mineral spirits or turpentine.
E. Lacquer: Clear, non-yellowing, acrylic emulsion, water-based coating, formulated with corrosion inhibitor benzotriazole, such as #11650 Eco-Borne clear lacquer as manufactured by G.J. Nikolas & Co., Inc., 2800 Washington Blvd., Bellwood, IL 60104 (708) 544-0320, or approved equal.

A. Coordinate dimensions with actual measurements of window openings and adjacent construction to match in kind.
B. Fabricate components to match originals in kind.
C. Join moldings to match construction of original sash exactly.
D. Machine sash elements to receive glazing panels. Machine sash elements of movable sash to receive weatherstripping, if appropriate, and hardware.

Part 3: Execution

A. Protection: Protect people, adjoining building surfaces, collections and landscape elements, et al from injury resulting from window restoration work. Use drop cloths or other coverings as necessary to protect interior finishes, floor and collections and exterior landscape material from dust and debris, etc.
1. Erect temporary protection over pedestrian walkways and at those points of entry and exit that must remain operational during restoration.

A. Examine the areas and conditions where window restoration is to be executed. Take all necessary field measurements. Notify the Preservation Manager of conditions detrimental to the proper and timely completion of Work. Do not proceed until unsatisfactory conditions are corrected.
B. General: Document all elements of windows to be restored for work of this Section, all elements adjacent to elements that are to be removed, and all other window elements that will be in any way affected by work of this Section. Show overall window elements and details of all damage or deterioration that might be considered as resulting from work of this Section. Key all notes to photographs to, clearly identifying portions of existing elements included in each photograph.
C. Form of Documentation: Document existing construction with high resolution (1 megabyte minimum) JPEG images on CDROM.

A. General: Remove all window components that require removal for restoration or for proper installation.
1. To minimize breakage, paint lines at the edges of window stops and parting strips must be cut/scribed first with a sharp knife before moldings are removed.
2. All nails will be removed by pulling them through the back of the moldings only. Representative nails will be tagged for Historic New England records.
3. Identify and label each component that is to be removed and repaired for reinstallation with window opening designator and location in jamb. Record numbers and locations of components.
4. Remove adjacent elements as required to modify or replace elements of window jambs, heads, and sills that must be altered to accommodate new window sash. Use all care necessary to prevent damage or deterioration of elements removed and elements remaining in place. Restore or replace all elements damaged during work of this Section to Preservation Manager’s satisfaction at no additional cost.
5. Store removed elements in a secure location safe from theft, damage, and deterioration.
6. Protect window openings to prevent water entry or human intrusion.
B. Glass Removal: All glass will be removed to accommodate sash restoration.
1. Label each pane of glass with location and orientation within the sash so that the historic glass can be returned to its original location and orientation. Use painters tape to label glass and consistently label on either interior or exterior to avoid confusion at reinstallation.
2. Remove all face glazing compound from each window sash using steam, infrared heat or other approved method.
3. Cracked glass is only to be replaced with prior approval of Owner. Fractured panes should be glued if at all possible, rather than replaced. Any replacement of glass in to be done in kind and all replaced glass is to be dated in corner under glazing for future identification.
C. Paint Removal: All paint will be removed from sash as needed in order to insure successful adhesion of new paint, excepting a 2” section to be retained for future paint analysis.
1. All paint removal shall be executed in compliance with all applicable federal, state, and local regulations.
2. Steam or heat will be used to carefully remove the paint while limiting the damage to the wood substrate.
3. As possible, depending on the technique used for paint removal, a two-inch band of undisturbed paint will be left on the interior and exterior of each pair of sash. Lightly feather the edges of each paint band. These bands will be used if future chromo-chronology is ever executed. If preserving areas of paint on the sash is not possible, craftsperson is to select samples from crevices where paint layers are most accumulated and best preserved and to provide labeled samples to Historic New England.
D. Hardware Removal: All hardware will be removed as needed in order to restore sash and hardware.
1. Scribe paint around hardware so that removal of hardware does not splinter adjacent wood.
2. Remove paint from hardware so that any crews may be loosened.
3. Tag and retain all hardware and screws.
4. Allow Preservation Manager to review all hardware so that a determination may be made as to whether hardware will be reinstalled.

A. General: Provide dutchman repairs where wood is structurally compromised. Wood repairs will not be made for aesthetic purposes. Dutchman repairs shall provide continuous smooth surfaces matching planes and profiles of wood members being repaired. Dutchman shall match wood being repaired in specie and cut. In wood for clear finish, grain pattern of dutchman shall match grain pattern of wood into which it is inserted.
B. Preparation: Neatly cut out existing opening as required to provide a prismatic void. Wherever possible create voids that will provide mechanical attachments as in dovetails. The amount of wood removed should be minimized but the amount should include all damaged wood and extend just past damaged wood to prevent spread of any fungus contained therein. Cut away area will provide ample glue surface.
C. Dutchman: Cut dutchman to exactly fit void, with exposed portion matching original profile of woodwork and just slightly proud of original surface. Orient grain of dutchman parallel to grain of element being patched. Where deterioration or loss at end of component requires dutchman repair, use a diagonal scarf joint for end-to-end joint between dutchman and remaining portion of component.
D. Installation: Clean glue surfaces with acetone or denatured alcohol. Insert dutchman using specified adhesive and clamp in place until glue is set. Where clamping is not feasible, use small brads; remove brads and fill holes after adhesive has set.
E. Surfacing: Plane or scrape dutchman to provide smooth continuous surface coplanar with adjacent wood. Do not damage or alter profile or finish of adjacent wood.

A. General: Fabricate new components for any components which are deteriorated in entirety and cannot be repaired with Dutchmen and epoxy.
B. In kind replacement: Except as specifically indicated otherwise, provide replacement elements of same specie with configurations, profiles, dimensions and joinery et al exactly matching those of existing elements.
1. Profiles: Remove coatings from profiles of existing elements before recording profiles to produce molding cutters to match existing profiles.
2. Molding Cutters: Cut custom blades as required to match original profiles and label knifes with project code.
C. Machining and Surfacing: Machine and surface all new and replacement wood elements to provide smooth even surfaces without saw marks or plane marks. Wood with surface irregularities, including but not limited to scratches, saw marks, and plane knife marks, visible after finish has been applied will be rejected and shall be replaced with properly finished wood elements at no additional cost.

A. General: Install new and restored sash as per contract. At completion of installation, windows shall be complete with all components and with unblemished paint and finish coats. All operating sash shall operate smoothly over entire height, and weatherstripping, if specified, shall provide weatherproof seal.
B. Sash Balances: If specified install sash with sash chains/cords and weights properly adjusted to allow sash to close securely, open completely to top of track, and remain stationary at any position in track.
C. Sash Hardware: Install any hardware, including sash lifts and sash locks, on restored sash in the same locations as originally. Adjust sash locks for smooth easy operation and firm, secure locking.
D. Wax: Treat unpainted sides of stiles and frame with wax for ease of window operation and wood protection.
E. Weatherstripping: If specified, install weatherstripping following manufacturer’s requirements to ensure smooth operation and weathertight closure.

A. General: Adjust operating sash and hardware to provide a tight fit at contact points and weatherstripping, if specified, and to provide smooth operation and a weathertight closure. Lubricate hardware and moving parts.

A. General: Re-glaze all window lites using approved pure linseed oil or soybean oil glazing putty. Glazing points shall be used to set glass.
B. Clean glass prior to glazing with non-ammoniated formula before reinstallation.
C. Panes with multiple fractures will be replaced in kind and the date will be etched date in corner beneath where new glazing will cover. Fractured glass will be repaired as possible by gluing with HXTAL NY-1.

A. Clean interior and exterior surfaces promptly after installation. Take care to avoid damage to historic and protective coatings and finishes.
B. Use only cleaners which do not contain ammonia. Windex, 409 and like products are not acceptable as they accelerate paint film deterioration.

A. General: Paint and finish new and restored elements of frames and trim to match original finishes and/or as specified by Historic New England contract documents. Prime and paint sash in controlled environment according to manufacturers instructions.
B. Prepare substrates for repairs by hand sanding with 100grit paper. The sides of the stiles (unpainted edges) of double hung windows do not need to be sanded unless special conditions require it.
C. After substrate is sanded, vacuum all surfaces and remove remaining dust with barely damp dust-free cloth. Allow surfaces to dry completely before priming.
D. Apply water repellant wood preservative to all surfaces of the sash.
E. Apply one coat of alkyd or 100% acrylic primer to all surfaces of the sash including putty beds (shellac based paint cannot be applied over glazing). On all window sash, extend primer and paint 1/16” onto glass to seal glazing. If sash is operable, it is important to paint bottom edge to prevent water intrusion.
F. Lightly sand surfaces after the primer has dried and clean of all dust.
G. Apply two topcoats of premium quality 100% acrylic paint to all surfaces. Color to match existing exactly unless otherwise specified.
H. Immediately after installation touch-up any disturbed areas of paint.

A. General: Remove historic sash hardware from existing sash to be replaced and remove sash pulleys from jambs. Store hardware in plastic bags or containers identified with sash number to ensure that each unit of hardware is reinstalled in its original location.
B. Remove lacquer coatings with acetone or lacquer thinner.
C. Strip paint coatings by dipping in chemical paint stripper.
D. After removal of paint and other coatings, thoroughly rinse in appropriate solvent and wipe dry with soft cloths.
E. Replacement Parts: Provide replacement parts, including operating parts and fasteners, matching original parts in metal and alloy, configuration, size, and finish for all missing and damaged parts.
F. Remove scratches and buff surfaces using like metal cleaning and polishing pads and polishing compound as necessary. Do not scratch finish with abrasive pads or wire brushes.
G. Provide lacquer finish on all copper alloy elements.
1. Preparation
a. Clean and degrease metal using solvent and burnishing with handheld bronze wool to provide surface free of dirt, dust, grease, oil, and other contaminants. Do not damage metal finish. If a surface is handled or contaminated, repeat cleaning and degreasing process.
b. Drying: Ensure that metal surface is completely dry.
c. Environment: Ensure that environment is dust-free before applying lacquer.
2. Lacquer Application: Build up coatings to produce 2-mil dry film thickness. Spray lacquer using “hot spray,” “airless spray,” or “electrostatic spray” methods.
3. Curing: Cure lacquer coatings by “baking” in shop at elevated temperatures following manufacturer’s recommendations.
4. Waxing: Protect baked lacquer coatings by hand application of two coats of hard paste wax.
H. Lubricate operating parts.
I. Store units in protective packaging.
J. Provide all missing fasteners for hardware. Fasteners must match all visual aspects of existing fasteners.

A. Protect windows from damage or deterioration until time of substantial completion.

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