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Professional Guide

Best Sash Window Locks for Security & Restoration: 2025 Expert Review

DJ

DR Joinery

Expert Joiner & Restoration Specialist

Published 12 December 2025

Sash windows are a defining feature of our local architecture, but they are notoriously difficult to secure properly. The 'meeting rail'—where the top and bottom sashes cross—is often the weak point that intruders target.

Many homeowners rely on old Fitch fasteners that have been painted over dozens of times. Whilst these might keep the window closed, they often offer little resistance to a determined forced entry. Furthermore, standard locks don't always account for the rattles and draughts common in older York terraces.

In this review, I've selected three locking solutions that I frequently encounter or fit during restoration projects: a budget-friendly swift solution, a professional-grade security stop, and a classic fastener that solves the issue of draughty meeting rails.

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Specs vs. The Real World

The Spec: "Insurance Approved"

The Theory

"Many locks claim to be 'high security'."

The Reality

Most insurance policies specifically require 'window locks with removable keys'. A standard latched fastener often does not meet this requirement; you typically need secondary screw locks (sash stops) to be fully covered.

The Spec: "Draught Exclusion"

The Theory

"Locks just secure the window."

The Reality

The right fastener acts as a clamp. By pulling the two sashes tightly together, a good lever lock actively reduces rattles and draughts—critical for facing the Yorkshire cold.

My Top 3 Recommendations

Three options to cover different needs and budgets

Window Sash Jammer Locks Set 2 PCS

Budget Pick
Window Sash Jammer Locks Set 2 PCS

Aongray

These surface-mounted jammers are a quick, cost-effective solution. Whilst primarily designed for uPVC, they can be screwed into timber frames to physically block the sash from sliding. They aren't the prettiest option for a heritage property, but they are effective.

Price£6.99 (at time of writing)
MaterialZinc Cast Alloy
OperationKey Locking Arm
The Good
  • Extremely affordable security upgrade
  • Acts as a visible deterrent to opportunists
  • Very simple to fit without specialist tools
The Bad
  • Aesthetic is modern and may clash with period joinery
  • Surface mounted (adds bulk to the frame)
  • Paint finish can chip over time

Installer Tip:

If you are fitting these to timber sash windows, pilot drill your holes first. Heritage timber can be brittle, and winding these thick screws straight in could split the frame. Ensure the arm swings clear of the sash cord to avoid fraying.

Priced at £6.99 at the time of writing

Check Price on Amazon

ERA 826-33 Sash Window Screw Locks - Brass (6 Pieces)

Quality Choice
ERA 826-33 Sash Window Screw Locks - Brass (6 Pieces)

ERA

This is what we call a 'sash stop'. It is the professional's choice for securing sash windows unobtrusively. You drill through the meeting rail, and the bolt secures the two sashes together. It's fully concealed when not in use and satisfies most insurance requirements for keyed locks.

Price£24.23 (at time of writing)
FinishBrass
Pack Size6 Pieces
The Good
  • Highly secure; bolts the sashes together
  • Minimal visual impact on heritage windows
  • Allows ventilation lock (if drilled at a second position)
The Bad
  • Requires precise drilling for installation
  • Keys can be fiddly if the paint is thick
  • Higher cost than surface latches

Installer Tip:

When drilling for these, be absolutely certain you are drilling into solid timber and not hitting the glass or the sash weights mechanism. I recommend using a depth stop on your drill bit to avoid going right through the outer sash.

Priced at £24.23 at the time of writing

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Lever Lock Sash Window Fastener Twist Catch Latch

Problem Solver
Lever Lock Sash Window Fastener Twist Catch Latch

WITPOCE

Unlike a simple stop, this lever lock (or Fitch fastener) solves the problem of loose sashes. The cam action pulls the top and bottom meeting rails tightly together as you twist it, creating a better seal against the York weather and reducing annoying rattles.

Price£8.42 (at time of writing)
FinishPolished Brass
MechanismSprung Loaded Twist Catch
The Good
  • Active compression reduces draughts
  • Traditional polished brass aesthetic
  • Sprung loaded for a positive 'snap' action
The Bad
  • Ideally requires a secondary lock for full insurance compliance
  • Must be aligned perfectly or it won't close

Installer Tip:

Fit the larger keeper part on the top sash first. Then, close the window fully and engage the lever to find the exact position for the bottom part. This ensures maximum tightness when locked. Do not rely on your eye; rely on the mechanism's pulling power.

Priced at £8.42 at the time of writing

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Frequently Asked Questions

Do sash window locks stop rattles?
Standard screw locks (stops) prevent movement but don't stop rattles. To fix a rattle, you should use a 'tightening' fastener like the lever lock mentioned above, which pulls the meeting rails together. Ideally, we combine this with decent draught-proofing strips during a restoration.
Can I fit sash locks myself?
Surface-mounted fasteners are manageable for a confident DIYer. However, drilling into the meeting rails for sash stops (like the ERA model) carries a risk of hitting the glass or splitting the delicate timber muntins. If you are unsure, it is worth consulting a professional joiner, especially for listed properties in York.
What is the best finish for Victorian sash windows?
Polished brass or antique brass is traditionally correct for most Victorian properties in York. Chrome or satin finishes generally suit Edwardian or more modern renovations better. Always check if the hardware is lacquered; unlacquered brass will age and tarnish naturally, which many purists prefer.
Do I need a key for my sash window locks?
For ground floor windows or accessible upper windows, most home insurance policies require key-operated locks. A simple butterfly catch is rarely sufficient on its own. The ERA screw locks reviewed here fulfill that requirement perfectly.

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