How To Change a Commercial Door Lock in 9 Easy Steps

The reason that I created The-Asterisk blog is that so much in life is not quite as it is purported to be. Everything seems to have those little asterisks which let you know that YMMV (your mileage may vary.) Most of my blogging centers around politics, which is a target-rich environment for asterisks, but from time to time I discover things in my personal life which I think would be of value to others.

Today, I was preparing a commercial suite for a tenant to move in on the first. Because we are splitting the suite, I needed to replace two passage door levers (they aren't door knobs anymore) with latches which have locks and  keys. I also needed to replace a worn out lever on the back door of the suite. I recently had purchased three locksets from a local locksmith company. You don't normally find commercial door hardware at Lowes or Home Depot. The sizing or backset is different between commercial and residential levers.

For the rest of this blog, I am going to call these lockable door levers a latch. It is just simpler that way and you all know what I am writing about.

What I will describe to you is how to replace an existing commercial door latch with a new one. I am not going to talk about drilling doors, measuring for new hardware or any other non-standard installation. The reason I am describing this at all is because instruction for anything you buy which requires assembly are usually horrible. Sometimes they are one small sheet with exploded diagrams and cryptic descriptions. Some are 80 pages thick with 18 different languages and some are so detailed that you literally cannot follow the instructions. Oh, and there is IKEA which gives you some stick-figure cartoon character with funny thought bubbles and no words.

My description will include industry standard terminology for the parts of the lockset. Don't get bogged down with it. Videos are available online, but this guide can be printed out and may jog your memory as you move along with your locksmithing. I will recap at the end.

So, let's get started.

  1. Open the box which contains the new lock. Take out the contents and lay them on a nearby table or cart. The lock usually comes put-together. Before you pull it apart, notice which end has the lock or the hole for the lock cylinder. Keep these pieces together and if you have enough room, lay the pieces out left to right in the order which you are taking them apart. Most keyed latches come with the cylinder out of the latch. For reference, the screw heads are always on the inside or the non-keyed handle side of the latch. This is important to remember. 
  2. De-install the existing latch. Start from the inside, or the non-keyed side. You will see a small hole near where the handle meets the door. Your new latch came with a tool which has a small pointy end. This will poke into that hole, releasing a springed clip so you can pull the handle off of the main cylinder assembly.
    • In case the poke tool which came with your new latch isn't long enough to release the catch, you can use a strong toothpick (what I used) or the end of a wire coat hanger.
    • The decorative cover is called a rose. Grab the rose like you would the lid on a jar of pickles and twist it counter-clockwise a half inch or so (anti-clockwise for those of you who still drive on the wrong side of the road.) It should come off by pulling it straight toward you.
    • Under the rose is the rose insert (I told you that there are obscure names for these parts.) There should be two screws which hold the rose insert to the inside support plate. The inside support plate is a piece of stamped metal which looks a little bit like a throwing star. This also has two screws in it. Unscrew these two through screws. These are pretty long and a cordless screwdriver comes in hand taking them out.
    • Once these two screws are removed, the rest of the assembly should practically fall out of the door on the other side.
  3. Remove and replace the latchbolt. This is the part that extends into the doorjamb and keeps the door shut and locked. It is held in with two screws into the side of the door slab. This is sometimes the hardest part because it may have become loose and stripped, rusted or the previous installer just did a bad job with it. Replace it with the new one. The screws are kind of funny looking. The end half is threaded like a wood screw and the head end is machine threaded. Screw the new one it carefully. Be careful to not strip out the wood or metal mounting bracket.
  4. Insert the new cylindrical housing (the largest piece) into the large hole in the door. There is a slot in one side of the housing. This slot lines up with the flared end of the latchbolt. It will be inserted from the outside (the side with the key.) Take the outside support plate (remember the throwing star piece?) and screw it onto the cylinder assembly. This plate may have two little prongs. These will go up against the door, into two small holes. Don't screw it down too far. For starters, make sure no more than one thread is visible on the shaft coming from the cylinder. You may screw it plate in further if you need to tighten up the fit.
  5. Place the outside rose insert over the support plate. This is a heavy round piece of metal with two threaded shafts. These two shafts extend inside the door. Usually they are oriented at 12 o'clock and 6 o'clock.
  6. Here is where you will wish you had three hands. On the other side of the door (usually inside), place the inside support plate over the lever sleeve (handle shaft) and line the holes up with the threaded shafts from the outside rose insert. Find two long screws (these are called through bolts) and fit them through the holes into each of the threaded shafts. Tighten the screws snugly and make sure everything twists freely. The latchbolt should be moving when you twist the cylinder shaft. Now tighten, but do not overtighten, these screws.
  7. The inside rose insert should have two holes which line up with two threaded holes in the inside support plate. Find two screws to to secure the insert to the support plate. These screws are usually short
  8. Slide the inside lever (the handle) over the lever sleeve and exercise it a few times to ensure nothing is binding.
  9. Install the outside lever and key cylinder. This was the trickiest part for me. At first I didn't understand why the key cylinder came separated from the other assembly. Found out that you have to assemble it properly to get the outer lever over the lever sleeve. 
    • Place the outer rose over the rose insert. You will need to line up the little indents with grooves in the insert, then twist it slightly clockwise. This keeps the trim attached.
    • Take the key out of the cylinder
    • If you look at the lockset like you were looking in the keyhole, you will see a little slotted hole towards the center of the housing. A little flat piece of metal, called a tailpiece, will allow the lock cylinder to connect to the latch through the cylinder housing. It must line up. One of my latches needed one with a 90 degree twist and I had to swap it with a straight one.
    • The lock cylinder will slide into the lever sleeve and the tailpiece slides into the slot.
    • Here is where the magic happens... Push the lock cylinder into the outside lever (you may have to remove a small piece of plastic trim.) Hold it inside the lever so that you can re-insert the key. 
    • Slide the lever with the lock cylinder installed onto the lever sleeve until it stops. Now, turn the key about 90 degrees, like you are unlocking the door. The lever should now slide the rest of the way in and you are now done. 
    • The trick was that turning the key allowed the spring-loaded clip to snap into place. If you ever need to remove the lever, you will need to turn the key before inserting the poke tool in the little release hole.
To recap:
  • Open box and place new lockset out on a flat surface in order left to right
  • De-install the existing latch
  • Remove old and install new latchbolt
  • Install the new cylindrical housing into the hole in the door
  • Place the outside rose insert over the support plate
  • Put the inside support plate over the lever sleeve and screw into place
  • Secure the inside rose insert to the inside support plate with two short screws
  • Slide the inside lever over the lever sleeve and click into place
  • Install the outside lever with the key cylinder over the lever sleeve and click into place
At first glance, this process looks a little daunting, but if you read through it while looking at the exploded diagram and comparing with your actual hardware, you will find that it is not really a difficult job to accomplish. Good luck!


Pretty accurate info and instruction. However, i would still suggest to hire a professional or at least find a neighbour who can replace these.
Door price is much higher than a locksmith service
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elina White said…
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