A locking mechanism installed on double-hung windows to secure the sashes together and prevent unauthorized opening while improving weather sealing.

A sash lock is a locking mechanism installed on double-hung windows to secure the upper and lower sashes together, preventing unauthorized opening while improving weather sealing and structural stability of the window assembly. This essential window hardware component typically consists of a cam-operated latch mounted on the meeting rail of the lower sash that engages with a keeper or strike plate on the upper sash, creating a secure connection that holds both sashes in the closed position. Sash locks are fundamental security and performance elements in window systems where they provide multiple functions including theft deterrence, child safety, improved weather resistance, and enhanced structural integrity, making them critical components in residential and commercial buildings where window security and performance are important considerations.

Sash locks are utilized in various window applications including residential double-hung windows where they provide primary security and weather sealing for bedroom, living area, and other occupied spaces, commercial buildings where sash locks contribute to building security and energy efficiency, historic restoration projects where period-appropriate locks maintain authentic appearance while providing modern security, specialty windows including storm windows and custom installations where locks ensure proper closure and sealing, and retrofit applications where new locks can improve the security and performance of existing windows. Each application requires appropriate lock types, materials, and installation methods based on security requirements, aesthetic preferences, and window specifications.

The design and components of sash locks include the lock body or mechanism that houses the operating components and mounts to the lower sash meeting rail, a cam or latch that rotates to engage and disengage the locking mechanism, a keeper or strike plate mounted on the upper sash that receives and secures the cam when locked, operating handles or levers that allow manual operation of the lock mechanism, springs and internal components that provide smooth operation and positive engagement, and mounting hardware including screws and reinforcement plates that secure the lock to the window sashes. Proper design ensures reliable operation, security, and weather sealing performance.

Fun Fact: The first sash locks were developed in the 18th century as window security became important in urban areas, with early designs using simple hook and eye mechanisms that evolved into the sophisticated cam locks used today.

• Sash
• Sash Cord