The upper sash on a double-hung window drops when its balance, pivot parts, or track engagement fail; inspect and reset or replace the faulty piece.
Applies to modern tilt double-hung units and classic cord-and-weight windows.
Top Sash Keeps Dropping On Double-Hung Windows: Causes And Fast Checks
When the top panel slides down on its own, the counterbalance no longer offsets weight. In tilt models, the shoe and pivot must stay locked in the jamb. In older wood units, a frayed cord or missing weight leaves the panel unsupported.
Quick Diagnosis Matrix
| Symptom | Likely Cause | Quick Check |
|---|---|---|
| Upper sash will not hold position | Weak or broken spring balance | Raise sash halfway; if it falls, spring force is low |
| Top sash drops after tilting for cleaning | Tilt pin not seated in balance shoe | Peek at jamb shoe; pin must be locked in the cam |
| Window is hard to close near the top | Balance tension too strong or shoe misaligned | Look for shoe set too low or binding track |
| Sash slams shut with a clatter | Snapped cord on weight-and-pulley system | Open side pocket; check for loose weight or broken cord |
| Only one side holds | One balance failed or shoe cracked | Compare both jamb shoes; one may sit lower or split |
| Sash rises on its own | Over-tensioned spring | Lower sash and see if it creeps up unaided |
How Double-Hung Counterbalances Work
Every moving panel needs a counterforce to feel weightless in the track. Makers use three common systems. Newer vinyl and clad wood units often use block-and-tackle springs hidden in a metal channel. Many tilt units use coil springs inside a compact shoe. Some classic wood frames still run cotton sash cords over pulleys to cast-iron weights.
When any part in that chain slips, gravity wins. Knowing the style in your frame guides the right fix.
Identify Your Balance Style
Channel spring (block-and-tackle): A slim steel channel with a sliding shoe. A stamp lists strength.
Coil spring (constant-force): A flat coil behind a cover. One or more coils stack per side.
Cord-and-weight: Cotton or braided cord rides over a pulley into a side cavity with a metal weight.
Match Spring Strength To Sash Weight
Spring force must match sash weight. If the channel shows a number stamp, that mark maps to a weight range. When stamps are missing, weigh the panel and choose the nearest rated kit.
Safety Notes Before You Start
Spring hardware stores a surprising amount of energy. Wear eye protection and gloves, and support the sash while you work. If your home predates 1978, treat painted parts with lead-safe care. Disturbing old paint can release dust, so use containment and cleanup methods or hire a certified pro.
Step-By-Step Fixes For A Dropping Upper Sash
The steps below cover the most common field fixes. Work both sides of the frame so tension and alignment match.
1) Reseat A Tilt Pin In A Channel Shoe
This is the fastest win after a cleaning tilt. The tilt pin on the sash edge must sit in the cam of the shoe. If it popped out, the spring does nothing. Many makers publish a short reset sequence that shows locking the shoe, seating the pin, then unlocking it so it travels again.
Andersen’s balancer reset steps show the exact motion for common tilt-wash designs; the idea is the same across most channel systems.
- Unlock and lower the panel a few inches. Slide a flat screwdriver into the shoe cam and rotate it to the locked position so the cam slot faces up.
- Tilt the panel toward you to 90°, align the tilt pin with the cam slot, and set the pin into the shoe.
- Rotate the panel upright and lock both tilt latches. Test hold at mid travel.
2) Reset A Channel Balance Pair
If both shoes sit too low, the springs feel slack. A reset moves the shoes back to an even height.
- Remove the panel. With a balance tool or flat screwdriver, hook the metal tab in each shoe, pull it up to mid jamb, and rotate the cam to lock.
- Reinstall the panel with both pins seated. Unlock the cams by lifting the panel slightly and lowering it. The shoes then travel with the panel.
3) Add Or Reduce Spring Tension
Windows with spiral or adjustable springs need periodic tuning. Too little tension and the panel sinks; too much and it wants to rise. Work in tiny increments and keep both sides matched.
- Pop out the panel and expose the spiral or tension rod in the shoe.
- Use the manufacturer’s tool to turn the spiral: clockwise to add turns, counterclockwise to remove. Make small changes, then test. Match both sides.
4) Replace A Broken Shoe Or Channel Balance
Plastic shoes can crack, and a failed channel loses lift. Replace in pairs on the same sash so balance remains even.
- Note the channel length and stamp. Order the same length and weight rating. If stamps are unreadable, weigh the panel and cross-reference the closest rating from the supplier chart.
- Release the top clip, slide out the channel, and swap in the new unit. Seat the shoe at the same height on both sides.
- Reinstall the sash and verify smooth travel and stable hold.
5) Repair A Coil Spring Pack
Coil packs use stacked springs tuned to sash weight. A broken coil or bent cover lets the panel drift. Coils carry small numbers that indicate force; mix-and-match only within the maker’s guidance.
- Remove the panel and pry off the plastic cover over the coil pack.
- Inspect for cracked carriers or snapped coils. Replace the damaged pieces, matching spring numbers on the coil tails.
- Reassemble, making sure the coil tail sits in the carrier slot without twist. If the carrier is gouged, replace it along with the coil.
6) Restore A Cord-And-Weight System
Historic wood frames use ropes and weights. A clean replacement brings back smooth, balanced travel.
- Open the side pocket, retrieve the weight, and remove any cord fragments.
- Thread new sash cord over the pulley. Tie to the weight, then tie the free end to the sash with the sash at mid travel. Use a figure-eight or bowline knot for a secure, low-profile tie.
- Repeat for the other side and test the hold. Lubricate pulleys with a small drop of oil if they squeak.
Field Tips That Prevent Another Drop
- Balance both sides every time. Even tension keeps the panel level.
- Keep tracks clean. Vacuum grit and wipe the jambs; sand or dirt eats shoes and creates drag.
- Lubricate sparingly. A dry silicone spray on vinyl tracks reduces chatter without gumming up dust.
- Mind the tilt latches. Always snap them fully before raising the panel.
When A Pro Makes Sense
Call in help when glass is cracked, the frame is racked, or the panel still slips after new hardware. A tech can weigh the panel, fit the right spring, and square the frame.
Balance Types And Fix Paths
| Balance Type | Tell-Tale Signs | Go-To Fix |
|---|---|---|
| Channel spring | Metal U-channel, stamped rating, nylon shoe | Reset shoes; replace channel pair if weak |
| Coil pack | Flat coil behind cover, stacked springs | Swap broken coil; confirm spring numbers match weight |
| Cord-and-weight | Side access pocket, iron weights | Replace cords; check pulleys and knots |
Parts And Tools Checklist
Keep a small kit on hand. It saves a second trip once the sash is out.
- Safety glasses, cut-resistant gloves
- Flat screwdriver, #2 Phillips, balance tool or spiral hook
- Replacement shoes, channels, coils, or sash cord as needed
- Dry silicone spray
- Luggage scale for weighing a removed sash
Lead-Safe Work Practices For Older Homes
Work on painted parts can create dust. If the house was built before 1978, follow lead-safe methods or hire a certified firm. The EPA’s renovation rule covers when certified renovators are required and lists safe methods.
Troubleshooting Scenarios
After A Cleaning Tilt The Upper Panel Dropped
The pin likely slipped out of the shoe. Reseat the pin and unlock the shoes so they travel with the panel again.
One Side Holds, The Other Side Slips
The weak side has a cracked shoe, broken spring, or a shoe set too low. Reset shoe height to match the strong side, then replace worn parts. If the channel stamp looks under-rated for the glass size, move up one rating.
The Panel Creeps Up By Itself
Tension is too high. Reduce a quarter turn at a time on spiral units, or drop to a lighter coil rating. A slight upward bias is fine, but the panel should still hold at mid travel.
The Panel Slams Down And The Cord Is Loose
In a weight-and-pulley frame, a snapped rope is the cause. Replace both cords and inspect pulleys for rough grooves. If the weight jammed in the pocket, dress rough wood so it slides freely.
Cost And Time Estimates
Reseating a pin and resetting shoes takes 15–30 minutes for one window. Spiral tuning adds a few minutes per side. New channel pairs and coil kits are modest in cost. Rope-and-weight parts are inexpensive; plan extra time for careful trim work. If hiring out, ask the tech to weigh the panel and note the spring rating on the invoice.
Simple Test To Confirm A Solid Fix
Raise the panel to one quarter, halfway, and three quarters. Let go gently while ready to catch. A correct setup holds at each point. Recheck after a week.
Bottom Line Repair Plan
Start with a reseat and reset. If hold still fails, tune tension. Replace shoes or balances next. For classic wood frames, swap cords in pairs. Work clean, protect your lungs, and you can restore smooth travel and a steady hold in an afternoon.