Replacing Your Old Locks

One of the more surprising situations for our customers here at Builders’ Hardware & Supply is arriving to our beautiful showroom to order new door hardware for your door and learning that we can’t just order you any lock.

We salespeople need some vital information to help you select the correct hardware for your door. To help you save time here are some steps to be ready to come in and order the correct door hardware for your door.

Type of Lock

If you are replacing an existing lock, the first step to figuring out what kind of lock or door hardware you need is to know what type of lock you are trying to replace.

Majority of time there are two different types of locks, mortise and tubular. The tubular lock is much more common in newer buildings, while a lot of older buildings are still using mortise locks.

Here is a picture of a tubular lock. As you can see it has a small square latch face that would stick out of the side of your door, so it can catch when it closes into the frame and stay shut.

Tubular Lock

Now here is a picture of a mortise lock. As you can tell this is a bit more complex than a tubular lock, with many more parts. It has a tongue sticking out of the side just like a tubular latch would, but the body of the lock is much different. A mortise lock would be much larger than a tubular lock, especially if it is an entry door lock.

mortise lock

We also always recommend bringing in your locks if possible, specifically mortise locks so we can help you find the exact right one if you are replacing an existing lock. For a more detailed depiction of the different types of locks read Mortise vs. Tubular Locks.

Door Prep

Of course knowing what type of lock you have (mortise or tubular) is the most important piece of information when replacing hardware, but another vital piece is knowing how your door is prepped.

Get your tape measure ready for these next couple of steps.

First, we want to measure the thickness of your door. Take your tape measure and just measure the edge of the door. This will determine your door thickness. The industry standard for exterior doors is 1 3/4 in, while interior doors are 1 3/8 in. Doors can be skinnier or thicker than these measurements as well, but not typically.

The next step is measuring your stile widths on the door. This picture should help you show what your “stile” is. Measuring this will help us determine what kind of locks can physically fit on your door. Some doors have thin stiles and only certain locks would fit on there. If your stiles are less than 4” then there could be some limits of what style trim you want for your lock and even whether it’s a mortise or tubular lock.


This next step might be the most important step in ordering your lock. You now need to measure your door backset. This picture should help a bit, but I will explain a bit more as well.

There are two standard door backsets, 2 3/8 inches and 2 3/4 inches. The way to measure this is to measure from the middle of the bore hole to the edge of the door. Before we can go any further, the bore hole is the hole in the door where your knob or lever will go. The edge of the door is where you would measure the thickness of the door.

This backset measurement will help determine how long of a latch you need for your door to close properly. The longer backset length, 2 3/4, inches tends to be used for exterior applications while 2 3/8 is more common for interior doors but that is now always the case.


Door Handing

Most door hardware is going to be handed, meaning you need to know what side of your door this hardware will go on. This part can get a bit confusing for a lot of people, but it is not that complicated. Look at this handing guide-

Handing Chart v2

Handing is always determined from the outside of the door. Usually whoever is helping you pick out this hardware will ask you what side of the door the hinges will be on. This answer will help determine the handing of your door. For example, while standing outside the door, a door with hinges on the left will result in the door being a left-handed door and vice-versa for right handed doors. For the right-hand reverse and left-hand reverse doors, the door swings out of the room or house instead of swinging in.

To recap, you need to know what type of lock you are replacing, mortise or tubular. The door thickness, backset, and door stile width are the next few things you need to know. Finally, you need the handing of your door. These steps should help you determine what kind of lock you will need for your specific door situation. This will also help you save a lot of time, so that when you come in you know what will help us pick out your lock right away.

Ben Goldstein – Showroom Sales Associate


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