How to Install a Key Lock on a Sliding Glass Door

Sliding glass doors are a beautiful way to let lots of light into your home, and they provide an excellent view of your lawn and garden when it's too cold to enjoy your patio or deck. Unfortunately, these doors are often located in a more secluded area of your lawn, which can make them a temptation for burglars. They typically come with only weak latches that don't offer a lot of security.

For extra protection, consider installing a key lock on your sliding glass door. Doing so can help keep unwanted guests out and young children in. A keyed lock on the outside of the door also lets you use your sliding glass door as an entrance if you'd like.

If you have small children, you may want a sliding glass door lock that can keep people in as well as out. A popular method for doing so is to install a keyed lock on both sides of the door. This prevents people without a key from opening the door no matter which side of it they're on.

There is a caveat, however. In some municipalities, locks that require a key from the inside are illegal. Instead, the interior latch must be a thumb switch or another keyless option. These laws exist as a fire precaution, allowing anyone inside the building to open the door with or without the key. If you want to use a key on both sides of the door, check with your local code enforcement office first.

Most sliding glass doors come with a traditional patio door lock rather than a keyed option. Many manufacturers, however, do make keyed locks for their doors in case you want one. You'll need to know who built the door if you want to get a lock from the manufacturer.

If you're not sure what you have, check the door. Sometimes, there is a sticker along the edge of the door stating the manufacturer and the model number. On other doors, you may find this information stamped into the door or door frame. It's easy to order a keyed lock with this information.

It's also the easiest way to add a keyed lock. With a kit from the manufacturer, it's a simple matter to remove your old handle and lock and install the new one. Because the lock is made for your door, you won't have to drill any new holes or worry about properly aligning the hardware.

If you're just not sure what make of door you have, you can use an aftermarket lock and key. Even these aren't one size fits all, however. You'll need to know the dimensions of your door and perhaps have a picture with you when you go shopping for a lock.

Once you have what you need, you'll need to disassemble your current door handle and then mark where the new screws and lock cylinder will go. Mark the door handle carefully so that things line up properly when you reinstall the lock. Drill two small holes in your latch where your screws will go and then make a larger hole for the cylinder.

File away any debris or rough edges. Place the door cylinder in your latch or handle and then reinstall it. Next, install the latch plate, again making sure all of your new parts are aligning properly. As always when changing locks, test the lock several times to make sure the key is working and that nothing is too tight or binding.