Broken Window Balance — How to Replace It

Common Symptoms

• Window sash falls down when released (won't stay open)
• Window requires a stick or prop to stay open
• Sash is extremely heavy and hard to raise
• Sash moves up on its own without being pushed
• Visible broken coil spring or disconnected balance rod
• Clicking or snapping sound when operating the window

Most Likely Causes

1. 1

   Broken Spiral Balance Spring

   Spiral balances use a coiled spring inside an aluminum or vinyl tube, connected to the sash by a shoe at the bottom. The spring fatigues and snaps after years of winding and unwinding. A broken spiral balance will hang loose in the frame channel, and the sash will fall freely with no tension. You can often see the broken spiral tube when the sash is raised.

2. 2

   Worn or Broken Block-and-Tackle Balance

   Block-and-tackle balances use a spring and pulley system in a plastic housing mounted in the window channel. The spring loses tension over time or the plastic housing cracks, causing the sash to fall or become hard to move. These are common in newer vinyl windows and are replaced as a complete unit.

3. 3

   Disconnected Channel Balance

   Channel balances (also called tape balances or coil balances) use a flat spring tape that coils inside a metal or plastic channel. The tape can disconnect from the sash attachment point, fray, or lose tension. A disconnected tape balance is easy to spot — the sash attachment point will have no spring tension.

4. 4

   Incorrect Balance Tension for Sash Weight

   Each balance is rated for a specific sash weight range. If the wrong tension balance was previously installed, or if the sash was replaced with a heavier or lighter unit, the balance tension won't match and the sash will drift. Matching the balance stamp number to the correct tension for your sash weight resolves this.

Quick DIY Checks

1. 1Step 1 — Identify your balance type: raise the sash fully and look at the side channels of the window frame. Spiral balances appear as round aluminum or vinyl tubes (about 3/4" diameter) running vertically in the channel, connected to the sash by a pin or hook at the bottom and a coiled spring at the top. Block-and-tackle balances are plastic rectangular housings (roughly 2" × 1") mounted at the top of the channel with a cord or metal tang connecting to the sash shoe. Channel balances are flat metal channels running the full height of the frame with a coiled spring tape inside. Knowing your balance type determines which replacement to buy.
2. 2Step 2 — Note the balance stamp number: spiral balances have a 2–4 character stamp on the tube (such as '15' or '2415') that indicates the tension. Channel and block-and-tackle balances have similar stamps on the housing. This number is critical for ordering the correct replacement — a balance with too much tension will push the sash up; too little and it falls. If the stamp is illegible, measure the sash weight (remove the sash and weigh it on a bathroom scale, halving for a two-balance window) and use a balance tension chart to find the correct stamp.
3. 3Step 3 — Tilt or remove the sash: most modern double-hung windows have tilt-in sashes — tilt the top of the sash inward by pressing the tilt-release latches (small tabs on the sides of the sash at the top of the lower sash). Once tilted, lift the sash out of the balance shoes. For older windows with non-tilting sashes, remove the interior stop molding with a flat pry bar to release the sash from the channel. Set the sash on a padded surface.

Repair vs Replace

Recommended Tools & Parts

• Spiral Window Balance (Replacement Pair)

  Spiral torsion spring balances for single-hung and double-hung windows. Sold in pairs (one for each side of the sash). Match the stamp number on your old balance (e.g. '15', '2015', '2415') for correct spring tension. Available in standard lengths from 13" to 28" — measure your old balance length before ordering. Fits standard 9/16" and 5/8" window channels.

  $15–$30

  Buy on Amazon →

• Block-and-Tackle Window Balance

  Replacement block-and-tackle balance for vinyl double-hung windows. The complete housing unit includes the spring, pulley, and mounting hardware. Match your existing balance part number or measure sash weight for correct tension selection. Most common on vinyl windows manufactured after 2000.

  $12–$25

  Buy on Amazon →

• Window Balance Shoes (Replacement Set)

  Plastic or metal sash shoes that clip into the window channel and connect the sash pivot pin to the balance. These often crack or break along with the balance. Replace them as a set when replacing balances — a cracked shoe will prevent smooth sash operation even with a new balance. Available in left/right sets to fit standard balance channel widths.

  $8–$20

  Buy on Amazon →

• Window Screen and Balance Repair Kit

  Multi-part kit including replacement spiral balances, balance shoes, and pivot bars for common double-hung window repairs. A good option if multiple components need replacement — kits typically cover a pair of balances plus two sets of shoes, which handles one complete sash.

  $20–$40

  Buy on Amazon →

• Window Channel Lubricant (Silicone Spray)

  Silicone spray lubricant for window balance channels and sash tracks. Apply to the channels after balance replacement to ensure smooth sash movement. Silicone is safe for vinyl, aluminum, and wood windows — do not use petroleum-based lubricants (WD-40) which attract dirt and degrade vinyl over time.

  $8–$14

  Buy on Amazon →

Links are Amazon affiliate links (tag: fixitfastai-20). Prices are estimates.

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