Securing Windows and Sliding Glass Doors

Nov. 3, 2014
Lock choices depend on the desired level of security and the different ages and abilities of the residents

Securing windows and sliding glass doors has always been a challenge, as customers want protection for openings that are mainly glass. An unauthorized person can easily break the glass and gain entry. Breaking glass results in making a noise that may or may not alert someone. Glass shards can remain in the frame and the surrounding area making it dangerous to gain access.

To resist entry, window bars and security screens can be installed. However, these options do not present an attractive "street appearance" for the home, apartment or condominium. For inconspicuous security, there are options that just restrict the opening of the window or sliding door.

Selling your customer locks for windows and sliding glass doors means selling secondary locking mechanisms that limit non-destructive methods.

Most windows and sliding glass doors have some type of a lock mechanism. An exception is louvre (jalousie) windows that have a handle, which moves down to tilt open the glass louvers in unison. Tilting the handle up closes the louvers against each other. Once the louvers contact each other, the handle can be tilted up to the stop position, exerting pressure against the louvers. 

Window Locks

The most common types of windows are the double hung (sash) windows and the extruded aluminum sliding (track) windows. With double hung window sashes, a sash lock is mounted onto the front sash top rail and a receiver is mounted onto the lower rail of the rear sash. The two components meet when both sashes are closed and only then can be locked.

The traditional double hung window lock has been upgraded to the keyed sash (turnbuckle) lock that is equipped with a wafer tumbler lock mechanism.

Ventilating double hung window locks provide the ability to partially open either the upper or lower sash. Some ventilating locks use a locking pin that slides through the upper rail of the front sash and into the stile of the rear sash. Hinged and sliding pin locks permit the upper or lower sash to be opened, providing ventilation. These locking mechanisms can be moved or removed, permitting free movement of the sashes. Multiple locks or holes permit the sashes to be opened different amounts.

For a double hung window that is rarely opened, installing a screw through the upper rail of the front sash and into the lower rail of the rear sash is an inexpensive solution. The screw must be removed prior to being able to open either sash.

Factory installed extruded aluminum sliding window locks not only prevent the sliding window from sliding, but also prevent the sliding window from being lifted out of the track when locked. Aftermarket extruded aluminum sliding window keyed and non-keyed locks attach to the upper or lower track, some only limiting the movement. They do not prevent the sliding window from being lifted out of the track.

To prevent removal when using an aftermarket sliding window lock that provides ventilation, install a thin piece of hardwood into the middle of the opening in the upper track. The wood will not permit the sliding window to lift high enough in the limited open position to lift out. Make sure the edges of the wood are tapered to permit the window to slide beneath without being affected. To remove the window, it must be slid over towards the open end of the track, just beyond the wood blocking.

For a window that is to be rarely opened, installing a screw through the upper track, just in front of the sliding window in the locked position, is an inexpensive solution.

Note: Never recommend keyed locks or locking methods such as screws on windows that can be used as emergency exits, i.e. all bedroom windows. If the window is locked, the only exit is to break the glass and crawl out through the opening once the glass has been broken.

Another window security concern is preventing small children from crawling out of the open window and harming themselves. Companies such as John Sterling and Mr. GoodBar Home Security Bars make child safety guards and bars for all types of windows. These safety products are installed on the interior of the window ,preventing a child from climbing through when the window has been opened. As a secondary consideration, these guards and bars permit ventilation.

Sliding Glass Door Locks

Sliding glass doors have been around for many years. They are available with wood, composite or extruded aluminum frames. Wood and composite framed sliding glass doors are normally equipped with a wider stile. This additional width increases the lock options from surface mounted to edge mounted hook locks that can provide a higher level of security.

There are wooden sliding glass doors with factory installed three-point locks. Many door manufacturer uses custom door prep to install the locks. The basic door prep is a slot cut into the stile to accommodate the top and bottom rods and the lock housings. Many of these locks are imported and are often not available through locksmith distribution.

Some extruded aluminum sliding glass doors are secured using a handle-mounted button lock whose mechanism captures a capped rod that extends from the jamb into an opening in the stile. Over the years, factory sliding glass door locks wear, becoming unsafe. It is not uncommon to see a wood stick or similar rod leaning against the door or slid down onto the sliding door track, providing the locking mechanism. As with the extruded aluminum sliding window locks, securing a thin block of wood in the upper track centered within the opening can prevent the door from being lifted when opened for ventilation only.

Aftermarket sliding glass door locks either take the place of the factory installed lock or are an auxiliary lock mechanism. Some of the aftermarket locks are just heavier duty versions of the extruded aluminum sliding window locks. Some are designed to replace the factory original lock mechanism.

When installing aftermarket sliding glass door locks, a key consideration is location. In a home with small children, installing the auxiliary lock out of their reach adds an additional level of security. The secondary lock can provide ventilation while making sure the door cannot be opened far enough for a child to leave.

Using these methods helps prevent intruders from gaining entry by removing or sliding the window or door to an open position, but it does not take into account the glass is breakable. To protect windows and sliding glass doors against glass breakage, window security films are applied to the glass, creating a protective barrier. These window security films are designed to keep the glass fragments together (similar to a windshield) once the glass has been broken. A secondary selling point is the films are available in a clear version or as a film that reduces the amount of heat and infrared light entering the home.

For this article, we will discuss some aftermarket sliding glass door locks.

The CAL Double-Bolt Lock is a surface-mounted sliding glass door lock assembly. This double bolt lock uses two vertical sliding steel bolts built into the main locking system that is mounted onto the doorframe. The jamb-mounted latch mechanism has accommodating holes for the vertical bolts. When unlocked, the vertical bolts are out of the latch. When locked, the vertical bolts are slid into the latch mechanism. The lock secures the door to the frame at two points, preventing sliding and lifting of the door off its track. The non-metallic components are manufactured of weather resistant nylon.

The Double-Bolt Lock can be used as a secondary or the primary lock mechanism. As an alternative to the factory installed lock, the Double-Bolt can be a replacement lock. CAL Security Enterprises offers replacement handles for both the exterior and interior side of the door. Dimensions of the CAL Double-Bolt are 7-7/8" Tall by 1-9/16" Wide.

The Major Manufacturing Octopod is a surface -mounted sliding door lock developed as an auxiliary locking mechanism. The Octopod is a gear driven rod lock that is mounted onto the face of a sliding door stile. The Octopod can be mounted onto either stile, along the bottom, top or middle of the door depending upon the rod length. The rod length options are 9”, 40” or 48”. They are extended or retracted by the gear shaped cam attached to the rear of a 1-1/8” mortise lock cylinder or thumbturn. If the Octopod is operated by a mortise cylinder, it can have the same keyway and bitting used by the other keyed locks.

Octopods with the nine-inch rods can be installed along the top or bottom track. When locking the Octopod, the key must rotate 360 degrees, extending the rod approximately two inches into the floor or header. In addition, a secondary hole can be drilled, providing ventilation while still being too small to permit someone gaining entry. Ventilation access holes should only be used with a mortise cylinder to lock the sliding glass door in place. The 40” and 48” rods can be used to locate the Octopod close to the middle of the door to enable easy locking and unlocking. In addition, mounting the Octopod at this location enables two 48" rods to have an engagement hole at the top and bottom track. With two rods installed, your customer will have the security of a two-point locking mechanism.

The Adams Rite 5017 Wood Door Deadlock is designed for wood framed sliding doors. This ½" wide by 4" tall by 1-19/32" deep lock has a narrow 1-3/16" backset which includes the 1.25" radiused faceplate. The 5017 lock body is through bolted into the locking stile. The laminated hook bolt has an adjustable bolt throw to accommodate the included strike box. The lock control options include a blank plate or cylinder pull on the exterior and a turn knob on the interior. The Adams Rite 5017 is available in the standard configuration or self latching.

For more information, contact your local locksmith distributor or the following lock manufacturers:

  • Adams Rite, 10027 S. 51st Street, Ste 102, Phoenix, AZ 85044. Telephone: 800-626-7590. Web Site:
  • CAL Security Enterprises, Inc., 16380 N.W. 84th Ave., Miami, FL 33016. Telephone: 305-827-9384. Web Site:
  • Major Mfg, 1825 Via Burton, Anaheim, CA 92806. Telephone: 714-772-5202. Web Site: