When it comes to securing the front door of a property, most lock installers will recommend a mortice lock, as it’s widely viewed as one of the more secure types of locks available. Strong, durable, and discreet, a mortice deadlock is installed directly into the door for top-tier security, making it a popular choice for commercial, residential, and public properties across the UK. While renowned for its impressive security, a mortice lock’s integrated design means that installing it in a door is best left to a professional to ensure it looks good and works properly.
Even the most experienced lock installers can struggle with the complex installation process of a mortice lock, which requires lots of precise measurements to ensure a snug fit and proper functionality, especially in a metal door. If you’re a lock installer who’s unsure about mortice lock dimensions in metal doors or just want to refresh your memory, our handy guide has you covered. We’ve spoken with leading mortice lock supplier Locks & Handles for all the top tips you need to consider when installing a mortice lock on a metal door.
Metal Door vs Wooden Door Fittings
Adding a new mortice lock is a great way to enhance your front door security, as these robust locks provide some of the best protection against tampering and forced entry, making them a worthwhile addition to safeguard your home, family, and valuables. However, installing a mortice lock can be a challenging process at the best of times, and that’s before you consider the different installation processes required depending on whether the door is wooden or metal.
Generally, installing a mortice deadlock and other types of door fittings on timber doors is much easier. This is because it’s much simpler to cut the various dimensions needed to install a mortice lock inside a wooden door without specialised tools. Metal doors are much tougher to cut through, so they require specialist cutting tools and much more precision throughout the installation process to avoid compromising the appearance and integrity of the door.
Even if you’re a professional lock installer equipped with all the necessary tools, you’ve likely spent much more time and effort installing a 5-lever mortice lock on a metal door compared to a wooden door. While a lock mortice is much more difficult to install on a metal door, the finished product will be an incredibly strong and secure locking system that enhances home security while complementing the aesthetics and functionality of the metal door.
How Dimensions Affect Metal Door Install
As mentioned above, installing a new lock mortice in a metal door requires lots of precision drilling and cutting to ensure a proper fit so that the lock and door work properly. If you’re installing them on metal doors, it’s crucial to understand how the mortice lock dimensions can affect the installation process to ensure that you do a good job. Thankfully, once you know how mortice lock dimensions affect metal door lock installations, the entire process becomes much more straightforward.
Backset
The backset is the measurement between the edge of the door and the centre of the keyhole. It’s crucial to measure the correct backset dimensions for a mortice deadlock so that it sits flush in the existing hole when replacing an old mortice lock. To measure the backset, simply lock measure from the edge of the door to the centre of the keyhole. You can remove the lock first and measure from the strike plate to the keyhole for a more accurate measurement. Either way, once you have the backset dimensions, just make sure that the replacement mortice lock matches them for a quick and easy replacement.
If adding a brand-new mortice lock on a metal door for the first time, you just need to ensure that the backset measurement is suitable for the door’s construction. For instance, if there are glass panels, then you’ll need to choose a backset measurement that avoids contact with these. You’ll find that the most common backset mortice lock dimensions in the UK are 57mm or 44mm/45mm, so most installations will use these measurements for a snug and functional fitting lock.
Case Size
The case size of a mortice lock, which covers its height, width, and depth, is also important for ensuring a proper fit inside the metal door. When replacing an older mortice lock, you’ll want to choose a replacement lock with the same case size dimensions for a straightforward installation. If the replacement lock has a larger case size or you’re installing a brand-new lock on a metal door, then you’ll need to cut a larger hole in the door for a proper fit.
Thankfully, mortice deadlock case sizes have two standard sizes here in the UK, 64mm and 76mm, making it easy to find the right fit for most metal doors. In fact, these standard sizes correspond with the standard backset mortice lock dimensions mentioned above. For example, a 64mm case size will normally use a 44mm or 45mm backset, while a 76mm case size will use a 57mm backset.
Conclusion
When replacing old locks or installing new locks on metal doors, it’s important to obtain the correct mortice lock dimensions to ensure proper installation. Be sure that you measure both the case size and backset dimensions of a mortise lock, pairing corresponding sizes to avoid any compatibility issues. Doing so ensures that the new mortice deadlock is seamlessly installed inside the door and fits into the frame for long-term durability and security.
