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WINDOW OPENING FAULTS

Sash Window Won’t Stay Open

A sash window that drops shut usually has broken cords, disconnected weights, failed spring balances or excess sash weight.

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Avoid forcing the sash or levering near glass

Large, high-level and emergency escape windows can be hazardous. Support heavy sashes and stop if the frame, glass or locking mechanism is under stress.

MOST LIKELY CAUSES

Start with locks, hinges and alignment

Broken sash cord The counterweight no longer supports the sash.
Disconnected weight The cord has detached from the sash or weight.
Failed spring balance Modern balance tension has been lost.
Excess sash weight Thicker glass or repairs have upset the balance.
◫ Symptom variations Match the opening, closing or support fault. ⌄
  • Sash drops immediately
  • One side falls faster
  • Cord is visible or loose
  • Rattling inside box frame
  • Problem started after reglazing
✓ Quick checks Safe checks before dismantling hardware. ⌄
  1. Support the sash securely.
  2. Inspect visible cords.
  3. Listen for moving weights.
  4. Check both sides equally.
  5. Look for balance tubes on modern systems.
Important: Test gently and support the sash. Excess force can twist the frame or crack glazing.
1 Step 1 — Identify cord-and-weight or spring balance Make the smallest safe correction and retest. ⌄

The repair method depends on the system.

2 Step 2 — Inspect both sides Make the smallest safe correction and retest. ⌄

One failed side can overload the other.

3 Step 3 — Replace and rebalance Make the smallest safe correction and retest. ⌄

Fit correct cords, weights or balances for the sash.

⌁ Why the problem happens How locks, hinges, balances and frames affect movement. ⌄

Sash windows depend on counterbalance. When that support is lost, the sash weight pulls it closed.

⌘ Advanced checks Further diagnosis for persistent window faults. ⌄
  1. Remove staff bead carefully.
  2. Inspect pulley condition.
  3. Weigh sash where balance selection requires it.
  4. Check pocket covers and weights.
  5. Assess draught seals for excessive friction.
◇ Tools and information needed Useful items for accurate checks. ⌄
  • Support prop
  • Screwdrivers
  • Pry tool
  • Sash cord
  • Tape measure
▣ Parts that may need replacing Common hardware linked to this fault. ⌄
  • Sash cord
  • Weights
  • Pulleys
  • Spring balances
  • Staff bead
! When to call a professional Conditions that should end basic DIY diagnosis. ⌄
  • The sash is large or very heavy.
  • Glass is loose or historic.
  • The frame is listed or conservation-sensitive.
  • Weights are inaccessible.
  • The sash must be fully removed.
? Frequently asked questions Common window opening questions. ⌄

Can I wedge the sash open?

Only as a temporary safe measure.

Why did it fail after new glass?

The sash may now be heavier than the balances or weights can support.

Should both cords be replaced?

Often yes, because they are usually the same age.