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Our Mission: Preservation.

Restore and Improve the Energy Efficiency of Important Historic Wood Windows.

Sometimes it makes better sense to keep the original windows rather than throwing them in the dump!


  • Sustainability-The window already exists
  • Historical authenticity-It's original and/or important to the buildings' character
  • Old growth lumbers are more stable, less prone to decay and hold paint better than today's plantation-grown wood

Why throw out a window better than one you can buy today?

General Specifications

Installers shall be experienced and knowledgeable of all current methods and trade secrets of Bi-Glass conversion techniques.

All sash removed from inside of building by Bi-Glass personnel to ensure proper numbering and ultimate return to proper openings. At time of removal sashes are marked for resizing according to weather stripping tolerances.

All original window stops numbered and reused unless otherwise specified. Window stop edges kerfed (saw cut) and wool pile installed. Eliminates wood on wood friction points.

Window conversion performed on premises in self-contained Bi-Glass trailer and/or offsite in Bi-Glass shop as required due to window size, complexity, epoxy consolidation, painting requirements, geographical location and onsite parking availability.

When Bi-Glass work performed onsite in mobile Bi-Glass trailer, all window openings without storm windows to be temporarily covered by Bi-Glass, as required, to prevent heat loss or damage from inclement weather. Sashes are replaced at end of each day.

When Bi-Glass work is performed offsite due to complexity, extensive epoxy consolidation, parking restrictions; or for other non Bi-Glass activities such as paint removal, de-leading, priming or finish painting, any window/door covers required to be provided, installed and removed by general contractor (GC) or others in a manner acceptable to architect. Bi-Glass will remove such covers to perform its onsite work if they are removable from inside the building.

Existing sash (and interior muntins) retained. Sashes and exterior muntins modified by cutting away existing putty or equivalent, increasing the width and depth of rabbet joint with patented Bi-Glass Router Guide Tool in strict adherence to Bi-Glass specifications.

Conversion and Epoxy Consolidation Standards

Existing wood sash shall meet Bi-Glass conversion standards as to: joints strong and complete, surface repairable with exterior rated epoxy. Sash or sash parts determined unusable at time of initial inspection or during conversion (rotted, decayed, and/or more than 15% moisture content as measured by Sonin Moisture Test Meter) and deemed repairable will be epoxy consolidated using WEST System, or FLEX-TECH elastomeric wood repair compound. Incidental epoxy consolidation (up to 2 cubic inches) included in bid price.

Window sash structural repairs to be made by Bi-Glass.

Any repair or epoxy consolidation required beyond incidental on window parts integral to the Bi-Glass conversion (i.e. sashes, window stops, jamboards, weight pocket covers and blind stops) shall be performed at a unit cost of $75 per unit (1 unit = +/- 4 cubic inches) with prior customer approval or covered by a job epoxy consolidation allowance.

The two bottom corners of the lower sash often (+/-70%) require epoxy consolidation and Dutchmen due to deterioration over the years where the end grains on the stile tenons have acted as wicks and drawn water up the stiles where some of it stays and rots the wood. A Dutchmen 5/8" thick x +/- 1" wide x +/- 5" long (or the entire length, if required) is epoxy consolidated into each lower corner. This repairs the rot, stabilizes the sash corners and provides a solid base for the weather strip kerf. Included in bid price.

Any window sills requiring epoxy consolidation or replacement shall be performed by Bi-Glass at a unit cost or by others prior to Bi-Glass work.

  • Minor epoxy consolidation repair $75 per
  • Major epoxy consolidation repair $175 per
  • Complete sill replacement or full epoxy consolidation $375 per

If necessary, any new replacement sash parts, or entire sash replacement duplicating the original sash as close as possible done by Bi-Glass at an agreed upon unit cost with prior customer approval.

Any replacement, repair or epoxy consolidation required on other window parts not integral to the Bi-Glass conversion on interior or exterior window parts (such as window stool, interior casing trim, exterior window trim, brick moulding, etc.) shall be performed by Bi-Glass at a unit cost, or by others.

Glass Specifications

All Cardinal 270 soft coat Low-E double-pane insulated units @ 7/16" DSB with a warm edge seal.

R Value w/o Argon    2.6       R Value w/ Argon    3.0
U Value w/o Argon    .38       U Value w/ Argon    .33
SHGC .42                            Visible Transmittance 72%

Glass is one piece double-pane unit. Selected interior metal spacer bars (dark in color) between the two pieces of glass to match selected interior and exterior muntin configuration may be required on large windows to prevent center of glass from touching during extreme weather changes and creating "Newton's Rings". IGU must be a minimum of 1/2" to accommodate interior metal grids.

Tempered (safety) glass according to state code and as specified in bid.

Glazing Specifications

Interior glazing using Norton Glazing Tape (black).

Exterior wood glazing stop installed in bed of siliconized acrylic sealant with supplemental nailing (glazing putty or compound eliminated).

Exterior muntins fabricated to closely match the original muntins for angle and reveal and applied to exterior glass with Norton exterior rated glazing tape (black) to follow interior muntin configuration. Some small expansion spaces are left at the muntin joints and then filled with a flexible caulk. This is necessary to insure full adhesion between the glass, glazing tape and muntins both at installation and then after installation to allow for slight muntin expansion and contraction during wet periods.

Exterior glazing stop and muntins fabricated from C & better select pine and primed with white primer/paint combination.

Bi-Glass of Shop Drawing

Bi-Glass Painting and Prep Specifications

Exterior (Included in bid price)

Bi-Glass will scrape/sand exterior of sash to a paintable level and apply one coat of white primer/finish combo paint. Custom water based colors may be used if paint is supplied by owner.


By request, and at an additional charge, flat surfaces sanded to 60/120 grit and muntins lightly "flap" sanded to remove loose paint.

Some paint chipping, wood splintering on grills (muntins) and marking may occur during conversion and is generally dependent on conditions of existing wood and underlying paint (or stain) job.

Window sash cosmetic repairs, additional sanding to feather edges of old paint (if required), additional priming and final painting done including final glass cleaning after Bi-Glass work by painter/others.

Any additional or required interior or exterior lead paint removal, containment, and/or abatement by others and performed prior to Bi-Glass work. Any final lead paint cleanup required for testing purposes to be performed by others. Bi-Glass uses HEPA approved vacuums in its daily clean up and is an EPA lead-safe certified firm.

All new window glass (inside and outside) cleaned and temporary stickers removed at time of sash installation. Any protection required during completion of any other construction activities provided by GC. Final cleaning to remove any construction dirt/filtrates etc. to be the responsibility of GC.

Alternative Painting Options

Option 1 (Requires taking sash off site to Bi-Glass Shop)


Prep exterior for final painting. Remove old paint (+/- 75%).

Prime and paint exterior of sash with 2 finish coats.

Some minor exterior touch up on sashes may be required by painter when exterior trim, etc. is painted.

Final clean exterior of glass before installing.


Flat surfaces sanded to 60/120 grit and muntins lightly "flap" sanded to remove loose paint. Finish prep and painting of sashes and window stops to be performed by others due to variations in interior finish colors.

Rough clean interior of glass before installing.

This option eliminates need for exterior sash painting (ladders, staging, etc.) after Bi-Glass installation.

Cost: $125-$175 per standard size opening

Any existing storm windows will be used as window covers while sashes are out of openings. Alternatively, OSB covers can be provided and installed.

Cost: $50 per opening if OSB covers provided by Bi-Glass

Option 2 (Performed by Painter Offsite)

Considerable painting time and painting cut in time can be saved if painter coordinates painting activities with Bi-Glass. Especially economical for multi-muntin sashes.

If desired, painter may pick up sashes and stops from Bi-Glass shop to perform any interior window sash preparation desired including stripping or scraping by painter or others. Note: This activity can be performed before Bi-Glass work. This way any damage done to the old glass is inconsequential as glass will be replaced with new double-pane insulated glass.

Sashes and stops delivered by painter to Bi-Glass shop for epoxy repair, restoration and double-pane glazing per specifications.

Painter to pick up converted double-pane sashes and stops in batches at Bi-Glass shop (Newington) and perform final prep, priming and painting per job specifications (interior and exterior). Bi-Glass work to be protected at all times and any damage once out of Bi-Glass possession is responsibility of painting contractor.

Painter to return sashes to either job site or Bi-Glass shop for storage until installation. Bi-Glass work to be protected at all times. Painter agrees to perform coordinated activities so as not to slow down or interfere with Bi-Glass conversion. Painter agrees to perform coordinated activities so as not to slow down or interfere with Bi-Glass conversion.

Some onsite minor touch up on sashes and parting bead may be required by painter after Bi-Glass installation.

Final sash glass cleaning by painter.

Cost: Per Painting Contract

Complete stripping of sash (by steam or chemical), priming and exterior finish painting can be performed by Bi-Glass off site at an additional cost. Window openings to be covered by GC.

Stain can be touched up on sashes with stained interiors after routing and before glazing @ an additional charge of $50 per window. New wood parts installed and visible from the interior (parting beads and sash stops) are stained with a similar matching stain.

Window Balance Systems Available and Weatherstripping Procedure

Please note: The Bi-Glass weather stripping process eliminates all wood on wood friction and impact points which are the main source of lead paint dust in operating double hung windows.

Non-tilt hidden balances ploughed into stiles of sash (System is more historically accurate as no vinyl is utilized):

  • Lower sash operational and upper sash fixed (or both sashes can be made operational at an additional cost)
  • New parting beads supplied and installed by Bi-Glass for proper weather stripping contact surfaces. Will require painting after Bi-Glass install.
  • Bottom sash to be weather stripped at parting bead "right angle" with jamboard using Schlegel Polyflex weather stripping. Eliminates wood on wood friction points.
  • Bottom operating sash weather stripped at bottom rail with silicone rubber Tube Seal. Eliminates wood on wood friction impact point.
  • Meeting rail (check rail) weather stripped with silicone rubber tube seal on upper sash. Eliminates wood on wood friction point.
  • Sashes to have wool pile installed at meeting rail ends to prevent air infiltration. Eliminates wood on wood friction points.
  • Top fixed sash weather stripped or caulked air tight.
  • Top fixed sash to be fixed shut with two custom sash support blocks.
  • Two custom sash stops installed at top of jamboard to prevent bottom sash from traveling beyond the limits of the hidden balance.
  • Window stop edges kerfed and wool pile installed for smooth operation and to prevent paint rubbing on wood. Eliminates wood on wood friction points.

On fixed upper sash installations, Bi-Glass to paint or stain upper and lower meeting rails which will be exposed (when windows are opened) with latex based paint or water based stain to blend with final window colors.

Tape Spring Balances (On sashes weighing >48 lbs, historically accurate used since 1890 on large windows at an additional charge):

  • Lower sash operational and upper sash fixed.
  • Same weather stripping procedure as hidden balance described above.

Tilt Compression Tracks (for smaller windows if tilt is desired, note vinyl tracks are visible from both inside and outside, not historically accurate):

  • Lower and upper sash operational.
  • Voids in jamboards covered with foil tape.
  • Cellular foam backing or fin type tilt tracks.
  • Top operating sash weather stripped at top rail and check rail with silicone ribbed rubber tube seal.
  • Sashes to have wool pile installed at meeting rail ends to prevent air infiltration.
  • Bottom operating sash weather stripped at rail with silicone rubber tube seal.

Installation Specifications

All sash counterweights removed (if weights will fit thru weight pocket openings). Weight pockets insulated to the extent possible and weight pocket covers replaced. Any open seams covered with aluminum tape which will be concealed by window stops.

All sashes planed, resized and refit to existing openings to provide for proper fit, locking and weather strip seal.

Existing window hardware reused if proper weather strip seal can be achieved. Hardware consolidated if any is broken or missing to provide consistent interior and exterior appearance. Broken, missing or new hardware replaced with approved substitute at an additional charge. Customer can purchase hardware themselves. Bi-Glass has three basic locks it can provide that are included in the bid price.

Operating casement windows, French casement windows and French doors to be weather stripped with brush poly fin weather stripping installed in a kerf cut on top, bottom and side (including astragal). Hinge side to be weather stripped with silicone rubber tube seal installed in a kerf.

Exterior Doors Specifications

Epoxy consolidation repairs made as required and door refit. Weather-stripped on lock side, hinge side and top with custom made wood stop with silicone rubber Tube Seal inserted in special kerf when tolerances allow. Or sides and top can be weather stripped with brush poly fin weather stripping installed in a special kerf. Door bottom to be weather-stripped with concealed custom brush or flap sweep installed in special kerf. Existing hardware cleaned, lubricated and reinstalled. Broken or missing hardware replaced with Architect approved substitute at an additional charge. May require a locksmith if Bi-Glass unable to fix broken hardware.

On Doors and high wall windows it may be advisable to install internal spacers in the IGU (insulated glass units) to prevent see thru when unit is opened and closed. This would be at an additional cost.

Work Schedule and Access Specifications

Onsite parking for conversion work trailer and supply van required for duration of Bi-Glass work. If onsite parking not available owner agrees to pay any additional charges incurred for Bi-Glass vehicle parking, or as otherwise provided.

Clear and easy interior access to each window shall be provided by GC or others.

Floor and area immediately surrounding windows are covered by Bi-Glass with Bi-Glass provided covers per EPA-RRP requirements and covered under EPA-RRP allowance. Any additional covering required to be supplied and installed by GC. Special care taken in sensitive areas where children under 6 years old and/or pregnant women reside per Lead Paint Acknowledgement Agreement.

For occupied buildings, a window work schedule should be made before the project starts that will maximize the safety for the occupants and minimize the disruption to their work schedule while at the same time allowing Bi-Glass to batch windows and perform its work efficiently without disruption and delays.

For occupied buildings, a designated area on each floor of building for storage of Bi-Glass work tools and materials and for light woodworking will be assigned.

Any window air conditioners, ventilations systems, etc. removed and re-installed by others. Bi-Glass may agree to remove and replace at an additional cost and accepts no responsibility for any damage.

All window treatments/accessories necessary to remove window sashes for Bi-Glass work such as curtains, shades, drapes, interior shutters, air conditioners, fans, etc. shall be removed (and replaced) by others prior to arrival of Bi-Glass. If Bi-Glass is required or requested to remove and replace such items it may agree to do so at an additional cost and Bi-Glass accepts no responsibility for any damage to such items.

Any security or alarm contacts on windows to be removed and replaced by others or Security Company. Bi-Glass accepts no responsibility for proper operation of the Security system after window conversion.

2-20 amp electricity outlets required within 75' of work trailer.

Any interior staging necessary for window conversion provided by Bi-Glass. Any exterior staging required provided by G.C or others.

If a dumpster is on site Bi-Glass may use for construction waste materials unless otherwise instructed in advance of bid.

Additional Specifications

Storm Window Removal: The EPA RRP rules enacted 4/22/10 require extensive ground protection when working on the exterior of a house build prior to 1978 that contains lead paint. Therefore, it is more cost effective for the painter to remove the storm windows when the exterior paint preparation and painting is done as he will have to provide ground covering at that time. This avoids double ground protection expense. However, Bi-Glass can remove storm windows at a cost of $50 each which covers the cost of ground protection, removal, transportation, recycling and exterior clean up. Final scraping, filling of any screw holes and any other exterior cosmetic wood repair to be done by painter. This storm window removal does not include removing any metal wrapping that may have been applied to sills or trim.

Bi-Glass is an EPA Lead-Safe Certified Firm per Certificate #NAT-37849-1. Our employees have been trained in lead-safe work practices and have their "Certificate of Attendance and Successful Completion" certificate on the job site at all times.

All material and workmanship warrantees as per Bi-Glass Contract. All warrantees are contingent upon payment in full, and progress payments made as agreed. Travel associated expenses may be charged if warrantee work is not a safety hazard and required to be performed via a special dedicated trip.

Existing insurance coverage as per insurance certificate to be provided. Increased coverage is available at an extra cost.

State of Connecticut Department of Consumer Protection License #544985 current license to be provided.

Construction and related permits: According to law, the ultimate responsibility for permits rests with the owner. However, the Bi-Glass process does not change the fenestration (size or location of window or door openings) and only changes the glass in the window sashes/doors and, therefore, usually does not require a special permit. Any permits required to be paid by others. Historical District permit requirements vary depending on the particular district's rules and regulations.

Any bid security or bonding requirements to be covered by G.C./others.

Prices are subject to final review of any job specifications and general conditions, prints, final contracts and any special conditions required by owner/architect and/or GC.

Totals subject to any change in opening counts or arithmetic errors.

Payment terms according to Bi-Glass contract or as otherwise agreed.

Any disruption in work sequence beyond Bi-Glass control once Bi-Glass activities begin due to other contractors or new requirements by owner/architect/ GC and/or any other instrumentality may result in additional Bi-Glass charges if extra time is required to complete Bi-Glass activities.