Window Balances: Sashes That Won’t Stay Up and Spring Repair

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A double-hung window that slides open smoothly and stays exactly where it is left is relying on a part most homeowners never see. The window balance sits in the side jamb, hidden behind the sash or a jamb liner, and its job is to offset the weight of the sash so it neither slams shut nor creeps open. When a balance breaks, the symptoms are obvious: the lower sash drops like a guillotine, the upper sash slides down and leaves a gap at the top, or one side rides higher than the other. This guide explains the main balance types, how to diagnose a failure, how to identify the right replacement part, how to tilt a sash out without damaging it and what the job typically costs. Homes built before 1978 may have lead-based paint on window parts, so this guide also summarizes EPA guidance for lead-safe work; consult a certified professional for testing decisions.

Part of our Structure & Exterior guide — start there for the full picture →

What a Window Balance Does and Why It Fails

A window balance is a counterweight or spring system that holds a vertically sliding sash in position. In a double-hung window, both the upper and lower sashes move, so each sash usually has a balance on each side, for four in total. In a single-hung window only the lower sash moves, so only two balances are present.

The balance pulls upward with roughly the same force that gravity pulls the sash down, so a correctly sized balance lets the sash stay put at any height.

Balances fail for predictable reasons. Springs lose tension after years of cycling. Plastic shoes and pivot pins become brittle with age and ultraviolet exposure, which is a real factor on sunny Front Range elevations. Cords fray or the cord attachment pulls out of a spiral rod. Paint, dirt and old weatherstripping can bind the sash in the track until a balance is overloaded. And sometimes a sash was simply reinstalled with the pivot sitting on top of the shoe instead of locked inside it, so the balance never engaged in the first place.

The Four Main Types of Window Balances

Identifying the type is the first step in any repair, because the parts are not interchangeable. Most windows built from the 1960s onward use one of three spring-based designs, while older wood windows often still have the original cord-and-weight system.

Spiral (tube) balances

A spiral balance is a narrow tube containing a twisted metal rod and a spring. As the sash moves, the rod turns inside the tube and the spring winds or unwinds. The bottom of the rod connects to the sash through a plastic or metal shoe, sometimes called a bottom-end attachment. Spiral balances are common in vinyl and aluminum replacement windows and in many wood windows from the 1970s through the 1990s. They are usually color coded, and the color corresponds to the spring tension and the weight of sash it can carry.

Block-and-tackle (channel) balances

A block-and-tackle balance uses an extension spring and a set of pulleys inside a metal channel, with a cord running out of the top or bottom to a shoe in the jamb track. The pulleys multiply the spring force, so these balances can handle heavier sashes. They are widespread in vinyl windows.

Constant-force coil balances

A constant-force balance uses a flat coiled metal ribbon, much like a tape measure spring, mounted in a housing near the top of the jamb. The ribbon unrolls as the sash goes down and attaches to a carrier or shoe in the track. As the name suggests, the force is nearly the same at every sash position. These balances are common in newer tilt-in vinyl windows and are often sold in pairs rated by sash weight.

Sash cords and weights

Wood windows from roughly the late 1800s through the mid-20th century commonly used cast iron or lead weights hanging in hollow pockets behind the side casing. A cotton or synthetic cord runs from the sash, over a pulley near the top of the frame and down to the weight. When a cord breaks, the weight drops to the bottom of the pocket and the sash loses its support on that side. Many older Denver, Boulder and Colorado Springs homes still have these systems, and most frames have a pocket access panel so the cord can be replaced with new sash cord or chain.

Symptoms of a Failed Window Balance

Most balance failures announce themselves within a few seconds of operating the window. Common signs include:

• The lower sash will not stay up. It slides down on its own or drops when released. This is the classic failed balance on one or both sides.
• The upper sash drifts down. A gap opens at the top of the window, letting in air and insects even when the window seems closed. Locks may no longer line up.
• The sash sits crooked. One side rides higher than the other, the sash binds, and the window may stick partway. A cockeyed sash usually means one balance has failed or one pivot has slipped out of its shoe.
• The sash shoots up. A balance that is too strong for the sash, often after an incorrect replacement, can push the sash open.
• A broken shoe or pivot. Pieces of white or black plastic at the bottom of the jamb track, or a pivot pin that has snapped off the sash, point directly to the failed part.
• A loose cord or no resistance. On a weight-and-cord window, a limp cord hanging out of the pulley or a sash that feels much heavier on one side means a cord has broken.

Before blaming the balance, check whether the sash is simply stuck. Paint bridging the gap between the sash and stop, swollen wood, debris in the track or crushed window weatherstripping can all make a window hard to move. Cleaning the tracks and applying a dry silicone lubricant sometimes restores normal operation without replacing anything.

Safety: Dropping Sashes and Window Falls

A sash that drops is more than an annoyance. A heavy lower sash with a failed balance can fall fast enough to pinch or crush fingers, and children are the most likely to have a hand on the sill when it happens. A propped-open sash, held up with a stick or a book because the balance failed, can also come down unexpectedly.

The opposite problem matters too. A broken balance or an upper sash that has drifted down can leave a window that will not lock or close fully, and an unlocked or partially open window is a fall risk for young children. In a 2026 release for National Window Safety Week, the U.S. Consumer Product Safety Commission estimated that about 5,600 children aged 12 and under were treated in emergency departments in 2024 after falling out of a window. CPSC recommends installing window guards, installing window stops so windows open no more than four inches, never relying on screens to keep children from falling, keeping furniture away from windows and, where possible, opening windows from the top instead of the bottom.

That last point depends on a working upper sash. If the upper balances have failed, the top sash will not stay open, and families lose the safer ventilation option. Restoring the balances, along with checking that window locks engage cleanly, is a practical part of childproofing.

Identifying and Ordering the Right Replacement

Ordering the wrong balance is the most common mistake in this repair. A balance that is too weak lets the sash drop; one that is too strong pushes it up. The goal is to match the original as closely as possible.

Read the stamp or label

Most spiral and many block-and-tackle balances carry a stamp, sticker or ink marking on the tube or channel. On spiral balances the marking commonly includes a length and a code for the spring, such as a number of inches followed by a series of digits or letters. Manufacturers use the code to identify the tension and the number of turns. The tube or rod color is another clue. Photograph the marking before removing anything, because the ink can be faint or partly worn.

If there is no legible stamp, record these details:

• The length of the balance tube or channel, measured end to end, not including any hook or shoe.
• The diameter of the tube or the width of the channel.
• The type of top bracket and bottom attachment or shoe.
• The approximate weight of the sash, which can be found by standing on a bathroom scale with and without the sash.

Specialty window hardware suppliers can usually match a balance from these details.

Replace in pairs

Both balances on a sash are the same age, so if one has failed the other is often close behind. Replacing both keeps the sash level. Shoes and pivot bars also vary by manufacturer and should be matched just as carefully.

How Balance Replacement Generally Works

The exact procedure depends on the window, so the manufacturer’s instructions take priority. The general sequence for a tilt-in window looks like this:

1. Raise the lower sash a few inches and unlock it.
2. Release the tilt latches at the top of the sash and tilt the sash toward the room.
3. Lift one side of the sash out of the track while the pivot pin slides out of the shoe. Some designs require rotating the sash to a specific angle before it will come free.
4. Set the sash on a padded surface such as a blanket on a table.
5. Unlock the shoe by turning the cam with a flat screwdriver, then remove the balance from the jamb, usually by unscrewing the top bracket.
6. Install the new balance, tension it if it is a spiral type, lock the shoe and reinstall the sash with the pivots seated inside the shoes.

Tilting a sash out safely

Spiral balances are wound under tension, and a rod that slips can spin hard enough to bruise a hand. Use the tensioning tool designed for the balance rather than pliers.

Sashes are heavier and more awkward than they look. A large double-pane sash can be difficult to control once it is tilted, especially on a second-floor window. Two people make the job easier and safer. Never lean out of an upper-story window to reach a sash, and keep children and pets out of the room while a window is open and the sash is out.

Forcing a painted-shut or swollen sash can crack the frame or the glass, and insulated glass that is twisted during removal can lose its seal and fog later, which leads to a separate repair covered in our guide to double-pane window repair.

Lead Paint on Older Windows

Windows are among the most significant sources of lead dust in older homes, because the sashes rub against the jambs and stops every time they move. EPA notes that approximately three-quarters of U.S. homes built before 1978 still contain some lead-based paint, and that old or worn lead-based paint on friction surfaces like doors and window sills can produce chips and dust that become a hazard when inhaled or ingested.

Balance repair on an old wood window often means removing stops, scraping painted-over sashes free and opening weight pockets, all of which can disturb paint. EPA’s Renovation, Repair and Painting (RRP) Rule requires that anyone paid to do work that disturbs painted surfaces in homes built before 1978 be lead-safe certified. In general, the rule does not apply to homeowners working in their own homes, though it does apply to landlords, home-based child care operators and house flippers. For do-it-yourselfers, EPA recommends lead-safe practices: containing the work area, wearing proper protection, misting surfaces before scraping or sanding, cleaning with a HEPA vacuum and controlling waste.

If the age of the paint is unknown, a lead paint inspection before work begins can answer the question. EPA advises that when the age of a home cannot be determined, it is safest to assume the paint contains lead.

Repair or Replace the Window?

Balance replacement is one of the least expensive window repairs, and on a structurally sound window it is almost always worth doing. Replacing the whole unit makes more sense when the balance problem is one of several:

• The frame is warped, cracked or rotted so the sash no longer runs true.
• The insulated glass has failed in multiple units and the seals are fogged.
• Replacement balances and shoes are no longer available for the product line.
• The windows are single-pane aluminum with poor energy performance.

For a single damaged sash, window sash replacement is a middle ground that keeps the frame. Our guide to window replacement cost covers what full replacement typically involves. On older wood windows where the sashes are sound but drafty, adding storm windows can improve comfort without removing original sashes. Old wood sashes may also need putty work, which is explained in our companion guide on window glazing.

What Window Balance Repair Typically Costs

Costs vary widely by window type, region and access, so these are general 2026 ranges rather than quotes:

• Parts only. A single spiral or block-and-tackle balance is often in the range of roughly $10 to $40, with pairs of constant-force balances sometimes costing more. Shoes and pivots are usually a few dollars each.
• Professional replacement. Window repair companies commonly charge a service call fee plus a per-window rate. Many homeowners see totals somewhere around $100 to $300 for one window, with the per-window price often dropping when several are done in one visit.
• Sash cord and weight restoration. Re-cording a weight-and-cord window can take more labor because stops and pocket covers must be removed and reinstalled, and old paint may need to be handled with lead-safe practices. Prices in the low hundreds per window are common, and more if the sashes also need glazing or wood repair.

Upper-floor access, hard-to-find parts and lead-safe work requirements all push costs up.

What a Home Inspector Checks

During a typical home inspection, an inspector operates a representative number of windows. A sash that drops, will not stay open, sits crooked or will not lock is commonly noted as a repair item, because it affects safety, security and egress. Inspectors may also note fogged glass, damaged sills, missing locks and peeling paint on older windows, which can be a lead concern in pre-1978 homes.

A home inspection is a visual, non-invasive assessment. The inspector will not usually remove sashes or open weight pockets to identify the balance type or code. If several windows have failed balances, a window repair specialist can provide a quote before closing. For more on what to expect, see our guide to hiring a home inspector and the overview of structure and exterior inspection topics.

References

• CPSC Urges Families to Protect Children During National Window Safety Week — U.S. Consumer Product Safety Commission
• Lead Renovation, Repair and Painting Program — U.S. Environmental Protection Agency
• Lead-Safe Renovations for DIYers — U.S. Environmental Protection Agency
• Reduce the Risk of Lead Exposure at Home — U.S. Environmental Protection Agency

Buying an older Front Range home with windows that drop, stick or will not lock? Get in touch with us to be connected with a local inspector who operates the windows and flags safety issues before closing.