How to Secure French Doors? Beef up Your Doorway Security

French doors – sometimes called double doors – are without a doubt one of the best-looking looking door options out there. While they can instantly transform a boring doorway into a bright inviting gateway to the outdoors, they come with their own set of downsides– with security being on the top of the list

If you consider that French doors are essentially two doors that secure to one another, you’ll begin to realize how much of a security liability they are when compared to standard single doors.

Luckily, there are several easy fixes you can take advantage of to greatly increase the security level of your French doors. Most of these are fairly low-difficulty jobs that can be done with just a few basic tools.

I’ll break down several of these methods to secure French doors, so you can rest easy knowing your home is well secured against any potential intruders.

Why are French Doors Hard to Secure?

So, why are French doors so hard to secure in the first place?

If you think about how a typical single door works, it’s normally secured with a deadbolt that connects directly to the door frame. The door frame is rock solid, and unlike a French door, isn’t attached to hinges and won’t move unless you apply a large amount of force.

French doors, on the other hand, are secured to one another. One door acts as the ‘passive door’, while the one that swings open is the ‘active door’. The active door is secured via deadbolt to the passive door rather than the doorframe – which means it’s nowhere near as secure as a single door.

passive door and active door

Another issue with French doors is that they often swing outward rather than inward. This means their hinges are on the exterior of the door, leaving them open to tampering with by potential intruders. If the pins are exposed, then anyone with a hammer and nail can remove your door from its hinges in seconds.

Most French doors feature a large glass pane, or sometimes several smaller glass panes held in place by flimsy molding. Unless the glass is tempered and well secured, it can be broken and a thief can simply reach in and bypass your lock and deadbolt.

Lastly, and perhaps most alarmingly, French doors can often be bypassed completely if someone knows what they’re doing. The passive door in most French doors is secured to the frame with a pair of sliding flush bolts.

flush bolt on french doors
Sliding flush bolt.

These flush bolts can be disengaged from the outside using only a long screwdriver to slide the bolt from the locked to the unlocked position. Talk about a security flaw!

How to Secure French Doors – Guide

I’ll go through several methods of beefing up the security of your French doors. Many of these methods can be combined to further beef up your French door’s security – turning them from a liability into an impregnable fortress.

Method 1: Secure the Flush Bolts

This is by far the easiest and most cost-effective thing you can do to secure your French doors. As mentioned previously, flush bolts can often be disengaged by sliding a screwdriver through the door and sliding the flush bolt into the unlocked position.

The way to prevent this is quite simple, and it’s sort of astonishing that manufacturers haven’t incorporated something like this into the design of these bolts.

To secure the bolt, simply slide the bolt into the locked position so the bolt slides into the hole in the door frame. Then, take a small screw and drive it into the slot in the bottom of the flush bolt. This will effectively jam the flush bolt so it can’t be opened without removing the screw.

Repeat the process on the other flush bolt for even more security.

Keep in mind if you use this method, you’ll need to remove this small screw should you wish to open the passive door. This isn’t a big deal for most people though, as 99% percent of the time the passive door doesn’t get opened at all.

Method 2: Beef up The Hardware

The next thing you can do to help secure French doors is beef up the hardware and deadbolt.

Just like with any other door, one thing you can do to instantly enhance your door’s security is to replace the included fasteners with longer, more sturdy ones. Oddly enough, locks and deadbolts often come with inadequate mounting hardware.

Take a look at the screws that are holding your door’s strike plate and hinges in place. If they’re flimsy little screws like mine, you’ll want to replace them with at least 2 ½-inch long screws.

different sized screws for strike plate
On the left is the original screw that came with the strike plate. On the right, is a 3″ screw I replaced it with.

Also, take the opportunity to examine your door’s deadbolt. For French doors, you’ll ideally want to get a lock with a there-point or multipoint locking system. These locks are designed to make up for the fact that you’ll be fastening the door to another door rather than a frame. They feature a lock that once engaged slides three separate deadbolts into place – one on top, one in the middle, and one on the bottom.

If you’ve got outward opening doors, then you’ll want to make sure their hinges can’t be tampered with from the outside. There are several different options you can go with here including set screw hinges, stud hinges, and hinges with pins that can’t be removed.

Method 3: Add a Door Reinforcement or Barricade

I like this option for double doors, as it adds a level of redundancy to your door setup. Even if an intruder manages to get past your deadbolt or your flush bolts, these act as physical barricades to prevent the intruder from getting inside.

There are a number of different options when it comes to door reinforcements and barricades. The sturdiest option is a brace that mounts to the floor itself and prevents anyone from kicking in your door.

The nightlock door barricade is a good example of this. It’s a sliding brace that attaches directly to your floor and when engaged provides a high degree of security.

nightlock door barricade original

Another solid choice is the folding-style door reinforcement locks. These act similarly to the night lock but mount to the upper portion of the doorframe rather than the floor. If you don’t want to, or can’t drill into your floor then these will work nearly as well. I’d suggest installing one on the passive door, and perhaps one on the active door for maximum security.

door reinforcement lock
Door reinforcement lock installed above french doors.

Method 4: Reinforce the Glass

While French doors are famous for their ornate and beautiful glass, this glass can be a liability if it’s not impact resistant. One easy way to beef up your glass is by installing a DIY security film over your existing glass panel.

These security films are generally easy to install, and only require you to apply the adhesive over the existing glass panel. Once installed, the security film acts like a magnet to hold any broken shards and pieces of glass stuck to the film.

That means that even if the glass is struck repeatedly with a blunt object, the panel will remain intact and continue to prevent an intruder from accessing the interior of the door.

While security film can work very well and is highly cost-effective, it can be overcome if an intruder is determined enough.

In that case, a metal safety grille installed over the entire glass surface is a more foolproof solution. These will prevent an intruder from getting through your glass panel, but they will reduce your door’s aesthetic appeal somewhat. They also won’t make your door impervious from someone breaking the glass panel and reaching inside to undo the deadbolt.

Method 5: Double Cylinder Deadbolt

This method is intended for when you want to prevent the above scenario from occurring. No matter how beefed up your door hardware is, if someone can simply break your glass, reach in and undo the deadbolt, then your all your upgrades are basically useless.

A double cylinder deadbolt is one that requires a key to unlock from both the inside and the outside. This means if you need to unlock it from the inside, you will need the key to do so. This means the lock will work even if an intruder managed to break through your glass and reach inside.

One thing to consider is that a double cylinder deadbolt can be an issue if you need to leave your house rapidly in case of an emergency. You will need the key to unlock the deadbolt from the inside, so someone could potentially be trapped inside if they don’t have the deadbolt key.

Denis Gardner

I've loved tinkering and fixing things for as long as I can remember. So, naturally, I gravitated towards DIY and home improvement when I bought my first home. Nowadays you can find me writing about my passions or messing around with my newest tool!

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