Wood Sash & Frame
Historic Wood Window Restoration in NYC
Sash repair, weight-and-chain rebalancing, epoxy consolidation, reglazing and weatherstripping — carried out by factory-trained artisans in our Newark workshop, EPA Lead-Safe certified, to LPC standards.
Why original wood outlasts replacement
The wood in a nineteenth- or early twentieth-century New York sash is not the wood you can buy today. It was cut from slow-grown, old-growth timber — tight annual rings, high proportion of dense heartwood, very little of the fast-grown sapwood that modern dimensional lumber is mostly made of. That density is why a sash from 1890 is still on the building, and it is the reason conservation practice treats original sash as a material worth saving rather than a consumable.
It also behaves differently in a wall. A historic wood window was designed to be maintained: putty renewed, paint renewed, cords replaced, a rotted rail cut out and patched. Every part is reachable. A modern sealed insulated-glass unit is designed to be replaced — when the seal fails, and seals do fail, the unit is finished, because there is no repairable joint in it.
None of that makes restoration automatically the cheaper choice. What it makes it is the choice that keeps a repairable, individually serviceable assembly on the building instead of trading it for one that has a service life and then ends.
The double-hung weight-and-chain mechanism
This is the part almost everyone gets wrong, so it is worth being precise about how the window actually works.
A traditional double-hung sash does not rely on friction or springs to stay where you put it. Each sash is counterbalanced by two mirrored counterweights — one on each side — hung on cords or chains that run up over pulleys mortised into the frame and down into hollow weight pockets concealed inside the jambs. The weights are matched to the weight of that specific sash. When it is set up correctly the sash is effectively weightless: you lift it with two fingers and it stays exactly where you left it, at any height.
The pockets are reached through removable pocket covers in the jamb, which is precisely why the system was serviceable for a century and a half. Cords wear and break. That is normal, expected maintenance — the mechanism was designed around it.
What most "repair" outfits do when they meet a broken cord is abandon the mechanism entirely: cut the cords, leave the weights lying in the pockets, and screw or seal the sash shut, sometimes fitting friction jambs to fake the operation. You then have a fixed pane in a double-hung frame — no ventilation, no egress, and a window that reads as original from the street while having lost the thing that made it a window. We rebuild the mechanism. Pulleys are freed or replaced in kind, cords or chains renewed, the weights re-hung and rebalanced against the actual weight of the restored sash.
Common failure points
Wood windows in New York fail in a small number of predictable places, and they fail from water and from paint — rarely from age alone.
- Bottom rail and lower stiles. Water sits on the bottom rail and wicks into the end grain at the joints. This is where perhaps 80% of the rot on a typical sash is found, and it is the most repairable location on the whole unit.
- Sill and sill horns. Standing water, failed paint film and a sill pitched flat by successive repairs. The horns — the projecting ends — go first.
- Failed glazing putty. Once the putty cracks and drops out, water gets behind the glass and into the rabbet, and the muntins and rails begin to decay from the inside.
- Cut cords and seized pulleys. See above. Very common, entirely reversible.
- Paint build-up. Decades of coats bridge the gap between sash and frame, glue the window shut, and bury the profile the architect drew. Stripping is as much about recovering the shadow line as about the substrate.
- Distorted frames and racked openings. Building movement puts the sash out of square with the frame, which is the real source of most draughts.
- Deteriorated parting beads and blind stops. Small, cheap components whose loss makes the whole assembly rattle.
Our restoration sequence
Fixed order, followed on every unit, most of it carried out off site in the Newark workshop so the building stays usable:
- 01 · Survey and tag. Each opening recorded individually — condition, profiles, dimensions, and a scope of refurbish or replace.
- 02 · Controlled removal. Sash removed under lead-safe containment; pocket covers opened and the weights, cords and pulleys assessed in place.
- 03 · Paint removal. Stripped back to sound substrate, recovering the original profile.
- 04 · Epoxy consolidation. Decayed but original wood stabilised where it stands, so the maximum amount of historic material survives.
- 05 · Dutchman repair. Where loss is beyond consolidation, a shaped patch of matching species let in and worked flush to profile — the member is repaired, not scrapped.
- 06 · Joinery re-wedged and re-glued. Mortise-and-tenon joints taken up tight so the sash is square and rigid again.
- 07 · Reglazing. Historic glass retained wherever it survives; missing panes matched to period glass, bedded and back-puttied properly.
- 08 · Mechanism rebuild and rebalance. Pulleys, cords or chains and counterweights restored to correct operation against the finished sash weight.
- 09 · Weatherstripping. Integral weatherstripping fitted into sash and frame — no change to sightlines, no change to the plane of the window.
- 10 · Reinstallation, repaint, closeout. Refitted on site, finished in the approved colour, documented for your records and for Landmarks sign-off.
Lead paint and EPA Lead-Safe compliance
Any New York building put up before 1978 should be assumed to contain lead-based paint, and windows are the highest-risk element in the building: painted surfaces that rub against each other every time the sash moves, generating dust exactly where children and pets are.
Disturbing that paint during window work triggers the federal Renovation, Repair and Painting rule and NYC lead-safety requirements. It is not optional and it is not a line item you can decline. HM is EPA Lead-Safe certified: the work is carried out under containment, with the dust controlled, the debris handled correctly and the site cleared properly afterwards, and we perform lead paint abatement and stabilisation where the condition calls for it.
This is one of the practical arguments for doing the paint removal in a workshop rather than on a windowsill in an occupied apartment. The containment problem is far easier to solve in a shop set up for it.
Energy performance after restoration
The honest version: a properly restored double-hung with tight weatherstripping and sound putty stops being draughty, because almost all the loss in an old window is air leakage rather than conduction through the glass. Fixing a loose sash in a distorted frame, renewing failed putty and fitting integral weatherstripping addresses the leakage directly.
Where a building needs more than that, the usual route is an interior storm panel or, in some cases, protective glazing — added behind or in front of the historic sash rather than in place of it, which keeps the original window and its glass on the building. For historic districts, Landmarks also permits a full building-wide high-performance retrofit using simulated double-hung units, but only if every primary-facade window other than special windows is replaced at the same time — there is no piecemeal version of that approach.
What we will not claim is a specific percentage saving. It depends on the building, the exposure, the existing condition and what else is done to the envelope, and any contractor quoting you a single figure for a whole facade is guessing.
Common Questions
Questions we get asked on this work
Can a window that has been painted shut for decades be made to work again?
Usually yes, and it is one of the most common things we are asked to do. Paint build-up bridging the sash and frame is what holds it shut; once the paint is stripped back to sound substrate, the joinery re-wedged and the frame trued, the sash moves. If the cords were also cut — which is common on windows that have been sealed — the counterweights are re-hung and rebalanced so the sash holds its position at any height.
What is a Dutchman repair?
A Dutchman is a shaped patch of matching timber species let into a sound area of the member after the decayed wood has been cut out, then worked flush to the original profile. It repairs a rail or stile that is too far gone for epoxy consolidation without scrapping the whole sash, which is why it is standard conservation practice rather than a shortcut.
Do I lose the original glass?
No, not where it survives. Historic glass — with its slight distortion and the way it moves light — is a large part of why an old window looks like an old window, and it is retained wherever it is sound. Where a pane is already missing or broken we match period glass rather than dropping in modern float.
Is restoring the weight-and-chain mechanism worth it, or should the sash just be fixed shut?
It is worth it, and fixing the sash shut costs you things that are hard to get back: ventilation, cleaning access, and in many rooms egress. A sash shut permanently is also a change to the operation of the window, which is one of the five attributes Landmarks tests — so on a landmark or historic-district building it is not simply a maintenance decision.
Does restoration need an LPC permit?
On a designated building, generally yes. Landmarks treats a full restoration methodology — stripping, reglazing and repainting a whole sash — as work requiring a permit, not as minor maintenance. Genuinely minor maintenance such as replacing a broken pane in kind or repainting in the same colour does not. We confirm which side of that line your scope falls on during the assessment rather than assuming.
Free Assessment
Get a free on-site assessment.
We visit your building, inspect the windows one by one, discuss any board or Landmarks requirements, and walk you through the options — restoration, replacement and approvals. No cost, no obligation.