The lower sash in my vinyl window won't stay up. Do I need a new window?

Probably not. A sash that won't stay up usually has a balance that has lost tension, and a weak spiral spring can't be fixed, only swapped. Cost guides put a balance or spring repair at about $50 to $100. The installer needs the window maker, the series and the balance's part number to order the right one.

Our 1920s windows have weights in the walls. Can the cords just be replaced?

Yes. The National Park Service describes replacing broken sash cords with new rope or chain, reaching the weight through an access door on the jamb near the sill or by pulling the trim. The sash has to come out to do it, so it's a good time to check the putty and paint.

Will a sash kit pass the energy code?

Replacement sashes and glass count as replacement windows under the energy code, so the new glass has to meet the U-factor rule. Ask the installer for the label on the unit before it goes in. See the energy-efficient windows page for the numbers.

We're in a historic district. Is a sash kit allowed?

Check before ordering. The Department of Energy's guide notes that historic review boards usually prefer keeping existing windows, and a sash kit changes how the window looks inside and out. Restoring the old sash and adding a storm window is the other route. Lowell homes in a review district start with a call to Historic Board staff.

Is a sash kit cheaper than a full insert window?

Usually. National cost data puts a new sash at $200 to $600 per window, against $450 to $1,500 for an insert replacement that drops a whole new unit into the old frame. The kit only works when the frame is sound and square; a rotted sill or out-of-square jambs push the job toward an insert or full-frame window.

Window Sash Replacement in Lowell, MA

Typical cost: most sash replacements run $200 to $600 per window in national cost data: about $150 to $400 for the sash, $50 to $200 for labor.
By material: roughly $200 to $500 installed for vinyl, $250 to $600 for fiberglass or composite, $300 to $800 for wood.
Smaller fixes: a balance or spring repair is about $50 to $100; a sash or track repair about $200 to $500.
Older wood frames: fitting a new sash into an old wood frame adds about $100 to $200 in labor per window.

Lowell Window Replacement can have a window contractor who measures before quoting call you back about new sashes, balances, cords and jamb liners. The call costs nothing. A sash job keeps the frame, interior trim and exterior casing you already have.

Window Sash Replacement Types: Kits, Balances, Cords and Liners

New white tilt-in replacement sash being lowered into vinyl jamb liners in an old painted wood window frame

Tilt-In Sash Replacement Kits

A sash replacement kit swaps the moving parts of a double-hung and keeps the frame. The old sashes and weights come out, new jamb liners go in, and new sashes with insulated glass tilt into the liners. The Department of Energy's guide notes that the new sashes are custom-built for the opening, with very little room to adjust. The side jambs need to be close to parallel, or air leaks around the sash. National cost guides price a new sash by window type:

Single-hung: about $200 to $500.
Double-hung: about $250 to $600, with two moving sashes and more hardware.
Casement: about $250 to $800 or more, since the sash is heavier and hangs on hinges.

The new sashes can take low-E double- or triple-pane glass. They still have to meet the energy code U-factor for replacement windows.

Window balance parts laid out on a workbench: a metal channel balance, a spiral tube balance and a flat coil spring balance

Block-and-Tackle, Spiral and Coil Balances

Newer double-hungs hold the sash up with spring balances hidden in the jamb. Too much tension makes a sash hard to move; too little and it falls. There are three spring types:

Spiral (tube) balance: a spiral rod and spring in a tube. The spring weakens with use; a broken one can't be repaired, only replaced.
Block-and-tackle (channel) balance: pulleys, a cord and a coil spring in a metal channel.
Constant-force (coil) balance: a rolled stainless steel spring that pulls out like a tape measure.

Fixing a balance runs about $50 to $100 in national data. Matching the part takes the window maker, the series and the balance's part number. When one balance goes, replace both sides so they start out new together.

Opened weight pocket in an old wood window jamb, a cast iron sash weight hanging on a frayed cotton cord

Rope-and-Weight Sash Cords

Wood windows from before the spring era use cast iron or lead weights hung on cotton cords running over a pulley at the top of the jamb. The cords fray and snap, and the sash then slams down or won't stay up. The fix is new rope or chain. A crew reaches the weight through the pocket door on the jamb near the sill, or by removing the trim if there's no door. Each weight should be about half the weight of the sash. With about 44% of Lowell's housing built in 1939 or earlier, many local double-hungs still run on weights.

Vinyl jamb liner channel installed along an old wood window frame, a sash shoe at the bottom of the track

Jamb Liners

A jamb liner is the track a sash rides in. In a kit job, new spring-loaded jamb liners give the sashes fresh tracks and take over from the weights. The Department of Energy's guide covers the steps:

Weight pockets: air-sealed and insulated once the weights are out.
Corners: the head, jamb and sill corners caulked before the liners go in.
Bottom of the liner: left unsealed where it meets the sill, so water can weep out.

Installer seen from behind pressing a new white double-hung window into an old painted wood frame, with a level on the sill and shims and a caulk gun on a drop cloth

Why Lowell homeowners call Lowell Window Replacement

One independent window contractor gets your request
Ask for the HIC number: MA contracts must show it
Written contract on any job over $1,000
The call and the referral are free

Sash Replacement Cost: What Moves the Price

National cost data puts most sash jobs at $200 to $600 per window, against $450 to $1,500 for an insert replacement window. Here is what moves the quote:

Material
wood sashes cost most to replace; vinyl least.
Glass
double or triple glazing, low-E coatings and gas fill add to the price.
Frame condition
easy access runs $50 to $150 in labor per window, and older wood frames $100 to $200. Repairs or rotted material push past $300.
Historic matching
custom work to replicate a historic sash costs more.

A simple seal repair (new caulk or gasket) runs about $75 to $150 per window and is worth ruling out first on a drafty sash.

When a Sash Kit Is the Wrong Fix

Rotted sill
The Department of Energy's guide calls the sill the most important part of the window assembly and says cracked or rotting sills have to be replaced first. See sill and frame repair.
Out-of-square jambs
Kits need near-parallel jambs; a frame that's racked needs an insert or full-frame window.
Historic district
The same guide notes that review boards usually prefer keeping existing windows. Restoring the old sash and adding a storm window keeps the original.
Lead paint
In a pre-1978 house, ask whether the crew is lead-safe certified before sashes and stops come out.