Mortise and Cylindrical Locks: All You Need to Know

Posted by on Nov 14th 2019

When it comes to mortise and cylindrical locks, there are advantages and disadvantages on both sides of the debate. For commercial clients who want top-notch security on their doors, it may come down to labor cost, or style preference. Either way, mortise, and cylindrical locks are the best choices for commercial doors and are a top choice for residential clients as well.

The following is a discussion of the differences between the two lock styles, their advantages, their disadvantages, and what kinds of security each lock can provide for residential and commercial clients.

Mortise locks

Mortise locks are reliable, durable, and strong. Mortise locks are meant to withstand the test of time, but they are more labor-intensive to install compared to other lock styles. They've been utilized in doors for centuries in Europe, and in the United States since the 1700s. Mortise locks come curtained for added security, although security personnel and professionals can help clients easily pick these locks with the proper tools.

Mortise locks are an excellent option for doors that will be opened, closed, and locked frequently, such as high-traffic doors in businesses and homes. Luckily, their parts are easily serviceable in case they do wear down or break, which makes up for the labor of installation.

The mortise lock comes with several different components, including the lock chassis, rose or escutcheon plates, two levers, and a mortise cylinder. Within the lock chassis itself, there are several mechanisms, such as the deadbolt, latchbolt or stop, auxiliary latch, and compression springs.

The internal components of the lock chassis usually come pre-assembled, so the chassis can just be installed into the drilled pocket of the door.

Mortise lock installation

One of the disadvantages to a mortise lock is that if the door isn't pre-drilled with a pocket for installation, the locksmith or installer must be able to drill the proper spaces in the door without compromising the integrity of the wood. Having some knowledge of woodworking is beneficial, but not necessary, as long as the installer is careful.

Once the pocket has been drilled, and the proper holes have been cut out for the cylinder, deadbolt, latchbolt, and auxiliary latch, the assembly is ready to be installed and assembled in the pocket.

The pocket is inserted into the door, appropriate screws, bolts, spindles, and the cylinder are attached, and then the external assemblies are applied. These assemblies include the escutcheon or rose plates, face plate, switches, and fasteners. The strike plate is inserted into the molding or trim of the door frame.

Mortise lock advantages and disadvantages

Mortise locks are incredibly durable, lasting decades or more, even with continuous use in high-traffic areas. There is plenty of variety available in both trim designs and lock functions. For business owners in particular, the integrated deadbolt that retracts in conjunction with the latchbolt is more convenient and durable. The overall security provided by a mortise lock is better than a standard bored, or cylindrical, lock.

The common issues with older mortise locks may include loose or disconnected handles, and a defective cam in the lock cylinder, which can cause the latch bolt to stop retracting when the key is inserted. Both of these are relatively easy replacements. Sometimes the retraction is impaired by a faulty spring, but this does not happen as often.

Cost can be a prohibitive disadvantage for mortise locks, especially if the doors are not already pre-cut for mortise lock assembly. The lock chassis and other components are not easily swapped out, as different manufacturers have different standards for their mortise locks which can be an issue if the lock needs to be replaced.

Cylindrical locks

Cylindrical locks, also known as "bored locks," are much simpler to install than mortise locks. Invented in 1920 by Walter Schlage, cylindrical locks are the most common door locks used today.

Instead of cutting out a pocket and additional holes for a mortise lock assembly, two perpendicular holes are drilled, or bored, into the door. One hole is drilled into the face of the door, which houses the handle; the other is drilled into the edge of the door, which houses the latch assembly. The latch assembly includes a latchbolt which connects to the cylinder.

The cylindrical lock comes with comparatively fewer components than a mortise lock. There are two knobs, one for the interior and one for the exterior of the door. The exterior knob is connected to a cylinder, which goes through the door, two rose plates, and a mounting plate to connect with the other handle. In the edge of the door, the latch assembly connects to the cylinder, and the assembly is inserted up to the face plate. The face plate connects with a strike plate on the door frame or molding.

Cylindrical lock installation

Like the mortise lock, if the door hasn't been pre-drilled for installation, the installer will have to create the bore holes themselves; however, this is a much simpler process than cutting a pocket, and the changes of damaging the integrity of the door are much smaller.

Once the two holes have been bored into the face and edges of the door, the latch assembly should be inserted into the door edge first and secured. Next, the exterior knob is inserted through the door, lined up with the latch assembly, and secured with the mounting plate. The other knob is then attached, and the strike plate can be applied to the door frame or door jamb. Experienced locksmiths and installers can complete this process in a minute or less, as compared to the more complicated mortise lock installation.

Cylindrical lock advantages and disadvantages

Cylindrical locks are extremely easy to install and replace. The process of rekeying is another advantage to the cylindrical lock and may make them a more appealing choice to business owners with employees who may need to rekey their locks occasionally. Bump keys can be used with cylindrical locks to help clients quickly and efficiently.

While cylindrical locks are ideal for both residential and commercial properties, they are not as durable for long-term high-traffic use as mortise locks. Although they are produced commercially in Grades 1 and 2, both for heavy duty and standard duty, mortise locks do last longer on the whole.

Additionally, the mortise lock assembly can include a built-in deadbolt assembly. For most cylindrical locks, these have to be added separately from the locking mechanism, with additional holes being drilled to accommodate the separate deadbolt.

Final thoughts

Ask your client what their plans will be for traffic through their doors, and what kinds of locks and lock features will be most convenient for them. From there, you can decide whether mortise locks, cylindrical locks, or a combination of both kinds of locks will best fit your client's needs. 

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