Exterior french doors and sliding glass patio doors are the most difficult exterior doors to secure. And it’s easy to see why – on french doors the weak point is where the 2 doors come together, on sliding glass doors the weak point is the standard hook type lock that the manufacturers provide. I have previously discussed ways to secure a sliding glass door.  First, let’s become familiar with the origins and definition of a french door. Then, I want to examine how to secure a french door.

What is a french door?

Typically, french doors are a pair of doors with glass panes that comprise most of the door surface except for the edges of the door. The edges of these doors are like a standard door to allow for hinges, locks and weatherstripping.

Because french doors are a pair of doors, one leaf is always used as the main door for egress. The other leaf typically stays locked unless you want to allow ventilation and light through or when you’re entertaining and need a wide opening to let more people pass. They’re also handy if there is a large item you want to bring in that won’t fit in a standard door.

Sometimes these are seen without windows on a front entrance but more commonly known as an opening to a patio or backyard. They allow a lot of natural light into the home and also allow a larger view to the outside than a standard window.

French doors have also been used for interior openings such as to an office or a master bedroom.

And why are they called french doors?

The french doors name does comes from France as you might have guessed but by way of Italy. In the 1400’s and 1500’s the Renaissance era, with their ideas on perspective and architecture, was flourishing within Italy.

During the 1500’s France and Italy were involved in the Italian Wars and the French forces were exposed to these new Renaissance ideals and brought them back to France when they returned home.

How secure are french doors?

French doors can be beneficial but unfortunately are not very secure with a lock alone. Your french door probably only has a lockable lever and a deadbolt. Even if it is a grade 1 deadbolt, because both doors have hinges there is nothing solid or unmovable for the deadbolt to latch into.

Products to secure a french door:

Armor Concepts Double Door Kit

french door reinforcement kit


Armor Concepts makes a lot of door armor or reinforcement kits for single and double doors. This is the kit they have for double doors and french doors. It has everything you need to secure the door except for the flush or surface bolt

Most home builders have already included flush bolts with the french doors they install. If that is the case with your french door then with this kit you’re good to go.

door reinforcement to prevent kick ins

This particular package comes with hinge reinforcements, strike and lock reinforcement, header reinforcement – for a flush or surface bolt – and also the Nightlock. Nightlock is actually made by a different company but Armor Concepts includes it in this kit and it is shipped separately from the reinforcements. 

GET THE DOOR ARMOR KIT FROM ARMOR CONCEPTS

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The reinforcements are screwed into the framing with the screws that are included. It includes 2.5″ screws for the lock and strike reinforcements and 3″ for the hinge reinforcements. The 3″ screws will get to the house framing for a more secure attachment.

how to secure a french door

It doesn’t require a lot of expertise to install these reinforcements. They are designed to go over the existing hinges. Only the latch and strike plates might need to be removed.

The Single Sided Deadbolt

Out of all the locking options to secure a french door, a single sided deadbolt is the best option.

Because french doors have no center frame or support they are very weak in the center. However, a deadbolt that locks both doors together and single sided deadbolts in the top and bottom of both doors are a good combination for securing both doors.

A single-sided or one-sided deadbolt is a deadbolt lock but only has a thumbturn on the inside and has nothing on the outside.

GET THE SINGLE SIDED DEADBOLT ON AMAZON

Most likely your french doors don’t have the cutout for this and the door will need to be prepped to receive this lock. A DIYer with intermediate skills might be able to do this themselves. I still would recommend getting a professional to have this done correctly.

Not only will both doors, in the top and bottom, need to be prepped but also the frame header and sill will need to be bored to receive the bolt.

Nightlock

Nightlock is actually made by a different company but Armor Concepts includes it in this kit and it is shipped separately from the reinforcements.  The Nightlock comes in two parts, a base that is screwed to the floor and the plate that slides into the base. The plate can be removed at any time. If you use this on your front door you will need to wait until everyone is home for the night before putting this in place. But if you use it on a back door it can be used during the day as well if the door isn’t being used. It can be used on single doors also.

GET THE NIGHTLOCK ON AMAZON

Flush bolt

flush bolt for french doors

This is a manual flush bolt, meaning the lever needs to be flipped to lock or unlock the inactive leaf. You will need 2 flush bolts, one at the top of the door and one at bottom.

There are other manual flush bolts that can be found here or here that will work just fine. But the one pictured here is an Ives flush bolt.

flush bolts on double doors

And this particular flush bolt is usually specified by architects for use in commercial buildings. It is made with all brass construction. And it will work in residential applications as long as your door is 1 3/4″ thick.

All doors need to be notched to allow a flush bolt to be installed. Unless your door is already drilled and notched for a flush bolt then this might be a task better left to professionals.

GET A FLUSHBOLT ON AMAZON

Protect the glass

unbreakable glass

Glass comprises a lot of the surface area of french doors. The glass needs to be strengthened or replaced. The easiest solution is to add a window film to the glass increases its strength. The film makes the glass in your french door work much like windshield glass. The glass will break but will stay intact and be very difficult for an intruder to get through. The window film comes in 30″ wide rolls. It can be found on Amazon or Home Depot.

Or as an alternative you could have the traditional glass in your french door replaced with laminated glass. It will do the same thing as the window film, just less mess for you.

And if you are in the process of buying french doors, buy them with impact resistant glass. Developed for hurricane prone areas, it will take a lot to break through this glass.

GET THIS WINDOW FILM FROM AMAZON

Cremone Bolt

cremone or multipoint lock to secure a french door

If notching or cutting into the door for a flush bolt is not something you want to do then you might want to use a cremone bolt instead. A cremone bolt is a surface applied lock used on double or french doors. This does not have a locking mechanism at the mid-point of the door like a typical door lock. The top bolt goes into the header and the bottom bolt goes into the floor. When the handle is turned both top and bottom bolts retract allowing the door to be opened.

This particular cremone bolt is made by Baldwin Hardware. They are a very popular manufacturer of decorative locks and handles. The lever of this lock comes in many different styles to fit your decor.

GET A CREMONE BOLT FROM AMAZON

Multipoint Lock

As the name suggests, this is a device that locks at multiple positions on the door. Like the Cremone bolt, it has a rod that slides into the header and the floor when the handle is turned. But it also locks at the midpoint into the other door. It locks at 3 points, there are some that lock at 5 points.

But to use this lock to secure your french door requires the door to be cut out so the lock will fit. Unlike the Cremone bolt, the multipoint lock rods are within the door.

The Straight Handle Lock

If both doors have a straight handle this is an easy to install lock you can use.

It installs by slipping over each straight handle and locking them together. It prevents the handles from being able to be rotated and disengaging the latch.

securing your french door

Even if the cylinder gets picked, bumped or snapped the handle still won’t be able to be turned.

GET THIS LOCK ON AMAZON

In addition, it acts as yet another impediment to a forced entry by holding both doors together. It is not designed for that situation but it looks like it would.

french door handle lock

My Recommendation

When you’re thinking about how to secure a french door, you want that opportunistic burglar to move on to the next house.

The goal in securing your family, home and valuables from intruders is to make it so difficult that it not worth the time and trouble.

Installing the single sided deadbolts in the top and bottom of both doors, the window film and the jamb reinforcement armor kit will make it very difficult for an intruder to get through an inward or outward swinging french door.

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5 Comments

Carol5162 · October 14, 2019 at 1:15 am

Those are interesting facts on how french doors came to be. We have a french door that leads to the back yard, which is only lockable by a lock and manual flush bolt that sometimes refuses to slide into position.. I see how the double door kit by Armour concepts can be very beneficial to our security. I have not seen this type of security before. Thankfully it looks easy to install. Thank you for the tip on protecting the glass with some window film. These are helpful suggestions.

Marc Ho · October 14, 2019 at 1:14 am

Hi there, I didn’t know there are so many things that can be learnt from securing a french door. I will definitely use this type of doors when I renovate my house. I will leave the installation to my carpenters though as I do not have the skill set.

Where can we purchase the french doors and its accessories?

Thank you for sharing. Marc Ho. 

    Bill Kiser · October 15, 2019 at 6:50 pm

    Hi Marc thank you for visiting. French doors and their accessories can be bought at those big box hardware stores like Home Depot or they can be purchased on Amazon. Although I think Home Depot has a larger selection.

Stephanie · October 14, 2019 at 1:05 am

Interesting article.  I just hace one question, I’ve seen a lot of people saying how convinient and beautiful French doors are, but are really affordable and if so, what would be the exact difference as to a normal wood door? For me at least, normal wood doors and metal-like doors are a must for me. At least regarding the insides of the house 

    Bill Kiser · October 15, 2019 at 6:43 pm

    I’m not sure what you mean by a normal wood door. French doors can be made out of wood or metal or even fiberglass. The difference between french doors and a normal door is french door is a pair of doors where one or both can be opened. 

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