Sliding Patio Door Locks

Harold Fink, Locksmith, CRL CPS
Sun, Jan 31, 2010


Means of entering through sliding patio doors and opening sliding patio door locks

The four most common means of entering through sliding patio doors or opening sliding patio door locks are use of key or inside latch, prying between the door and frame, lifting of the door from the track, and breaking of the glass. There are some sliding patio door locks, secure installation techniques for sliding patio doors, and considerations for sliding patio doors that make such means of entry harder.
Due to the light structure of most sliding patio doors and their locks, entry can be gained by simply applying pressure to the lock and strike area by prying with a large screw driver or pry bar. This means of entry is fast, easy, and in most cases so quiet it is almost undetectable. While several styles of strikes and locks are applied to these doors, the strikes are typically very light. Some of the heavier strikes are little match for a crow bar or pry bar.
Probably the all time most popular remedy for this type of entry is the old broom handle in the track. While there is no doubt as to the effectiveness of this method in preventing a pried opening, it falls short in protecting the door against being lifted.
Like prying, lifting is quick, simple and noiseless. Because most homeowners are not familiar with the design and construction of the patio door, they don’t realize that the door is actually lifted and dropped onto the sliding channels of the doorway. And, by design, what goes in can come out. Just as they are lifted into place, these doors are just as easily lifted out of place. Even in the closed and locked position, although a bit more difficult, the door can be removed from its tracks.
For the burglar, the access is made by placing a crow bar or pry bar under the door and lifting the door of its track. While broom handles, or large dowel rods, when cut to length to fit snugly between the sliding door and the frame, will prevent sliding open of the active door, they won’t prevent a lifting attack against the door. Again, except for the strike and the lock.
It should also be noted that patio doors are manufactured with either the sliding door on the outside or on the inside. Those mounted outside are the most prone to prying and lifting, and are the hardest to protect.
What about just breaking the glass and walking through the opening? To say that burglars won’t break the glass because of the noise is a myth. The common misconception is that breaking the large pane of glass from a patio door is so noisy that doing so alerts the residents or neighbors. Realistically, however, the effect of tempering causes this glass to crumble into small pieces, and breaking is often very quiet.
In one instance, an apprentice of mine broke a patio door window with the new residents quietly talking in an adjacent room. The shattering of the glass was so quiet that they did not know it was broken until I informed them. It is even more unlikely that it can be heard while sleeping or by a next door neighbor. At this point, about the only way to offer some protection to large areas of glass is by providing an application of safety film. Offered by some manufacturers, this film makes it difficult to penetrate an opening by breaking the glass.
Generally it is feasible for a locksmith to do this type of installation, but efficiency with your time can be maintained by referring your customer to a qualified installer of such films. I normally refer this work to a qualified tint installer that I know is familiar with safety films and is willing to do on site work for residential customers. Also, when I refer a customer to any other compay, I qualify my referral by asking that they let me know how well the installation went if they do business.

For the most part, I now will recommend complete replacement of sliding patio door units from the rough opening with modern, energy efficient door units that swing in or out, and even offer two swinging doors, if necessary. This topic will be covered again in closing. For this article, we will cover what I consider to be interim solutions to the customer’s overall security, should their budget not allow complete removal and replacement of the sliding patio doors.

For the locksmith, we are still armed with locks and techniques for deterring prying and lifting of sliding patio doors. In the case of the door that was the subject of our burglar, we have installed the Octopod by Major Manufacturing, as well as several other brands of locks. When properly installed, this patio door lock provides protection from both prying and lifting. One of the features of the octopod is that is utilizes a mortise cylinder lock, allowing the lock to be placed on nearly any keyway.
In our installation, we used a thumb turn. This was done to avoid the need for a key to open the lock during an emergency and for convenience. The disadvantage of this application is that without the positive and negative locking of the pin tumblers in a standard lock, a hard blow to the lock, door or bolt may, in some instances, cause the thumb turn to release and allow the bolt to drop to the unlocked position. Also, this application cannot be used if an extra bolt or strike hole is being drilled to allow venting.
The installation of this lock is extremely simple and fast. After assembling the lock, tightly close and lock the door using the existing lock. This makes sure that it is in the fully closed position for mounting the Octopod.
Place the Octopod on the latch side door stile, allowing enough height for the bolt to engage and disengage the header or upper frame of the door when it is locked and unlocked. Holding the unit onto the door, mark the mounting hole locations.
Carefully drill holes for the mounting screws. Be extremely careful. Remember that the glass extends back into the frame up to ¾”. If you are drilling too close, even nicking the glass with the edge of the drill will cause the glass to shatter. This scenario is what caused my able apprentice to witness the glass breaking into many thousands of pieces.
Mount the lock to the door. Either the bolt guide can be attached or the strike hole can be marked and drilled. We usually mark and drill the strike hole first. To make the mark simply thrust the bolt up into the door’s header or top frame. A gentle tap on the bottom of the bolt allows the marking tip of the bolt to leave a nice, clearly visible mark on the surface of the header.
With the hole drilled, we fastened the bolt guide to the door. Location of this component is critical. The guide is to be set as close to the top frame as possible to prevent lifting the door out of the track. On the other hand, the top frame of the patio doors are not always level across the width of the door. In fact, many older doors may have sags at the middle of the door up to 3/8 “. Under such conditions, the guide may clear the frame while the door is shut, but hit the frame as the door is opening. To properly set the guide, hold it against the door at the highest position possible when the door is closed. Then, while holding the guide, slowly open the door to the full open position. If the guide hits the upper frame anywhere across the opening, it must be lowered.
Continue to hold the guide against the door and move the door to the position where the upper frame is at its lowest point. Set the guide approximately 1/16” below the frame at this point and mark the door for drilling the mounting holes. Check and measure twice, cut once.
Drill the hole and fasten the bolt guide to the door. Open and close the door, checking for proper operation and clearance. If desired, a second strike hole can be drilled, allowing the door to be locked open just enough for venting.
In some applications it may be necessary to shim the lock to clear various style door frames and trim. Shims are available to raise the Octopod lock and guide away from the door. The Octopod is available through authorized Major Manufacturing distributors.
Next, we cover the least a locksmith should do to prevent prying and lifting. The door used for this application is an outside slider, one of the more difficult types of doors to protect. To deter prying, we used the locksmith’s version of the old broom handle-the Charlie Bar. This unit is inexpensive and easy to install. After cutting to length, our unit was fastened to the door and operational in 15 minutes.
Of course, also like the old broom handle, the Charlie Bar does not protect against lifting. So, we need to add another level of protection. In this applicaation, we simply added several large flat head screws to the upper track.
Three of these screws were added to the track, across the entire opening -one on each end and one in the center. The screws, 3-½ “ in length, were fastened into the header, and then lowered to where they just cleared the door. Because the center of the upper rail on the door is hollow, we made sure that the screw and its head were off to the side. Here the screws ride directly above the edge of the upper door rail, and prevent it from being lifted.

Do not forget that in the larger picture, it may make perfect sense to suggest complete removal of the sliding patio door unit and replacing it with a modern, double insulated door pair that swings in or out, complete with frame, into the rough opening. The cost of this door pair, with one or even two active doors that swing in or out, may be affordable enough for your custmer to gain the added level of protection that you will afford them when the proper door locking hardware is installed. Ideally this door hardware will be of the same type as the rest of the house. Design considerations such as finish and lifetime of the finish, as well as space limitations inside or outside of the door opening are able to be addressed by replacing patio doors as well. If you are recommending high security products to your customer, this is usually what I will recommend when I see sliding doors on that same house. The benefits of energy efficiency, coupled with the convenience of using one keyway, and additional overall security offered by high security locks makes this recommendation the one that I am most likely to make, in the interest of my customer’s complete security. Part of our properly making this suggestion is being well informed of how much such a door pair, complete with frame, would cost in addition to its installation. To forget to suggest the complete removal and replacement of the sliding patio door with a modern, energy efficient door pair would be doing a disservice to your customer, if you feel that it is within their budget to consider doing so. Any loss, due to compromise of a customer’s home security, will far exceed the difference in cost between interim locking solutions for sliding patio doors and their complete replacement with much more secure, modern door pair assemblies. Additionally, the convenience that a qualified locksmith contributes in this situation is something that I find all of my customers appreciate. You should not rule out that many times what seems to be an obvious solution to us may not seem so obvious to others. Knowing what modern door pair assemblies sell for, and having the ability to perform the work, are components to providing solutions to our customers. This helps the customer make better decisions for their safey and security of their home and family, knowing what it would cost to make a considerable improvement in security of their home by replacing sliding patio doors.