The best deadbolt setup for French doors is an ANSI Grade 1 single cylinder deadbolt with a 1 inch throw on the active door, plus flush bolts top and bottom on the inactive door and a reinforced strike. In Los Angeles that is installed in a single visit and quoted upfront by the door pair.
Why French doors are a weak point
A pair of French doors has two problems a single entry door does not. First, the doors meet in the middle, so the “frame” the deadbolt throws into is another door, not a stud wall. If the inactive leaf is held only by a slide bolt with short screws or a latch at the top, a shoulder to the seam moves both doors. Second, the glass. Most French doors are divided lites or a full pane inches from the thumbturn, which is what makes double cylinder deadbolts tempting and also what makes them a code problem.
In our work across Beverly Grove, Hancock Park, Culver City and the Hollywood Hills, French doors are the rear or side entry on a large share of single family homes built between the 1920s and the 1960s, and they are the door burglars test after finding the front locked. Getting the pair right is worth more than upgrading the front door a second time.
Your options, compared
| Option | Best for | What is on the quote | Notes |
|---|---|---|---|
| Grade 1 single cylinder deadbolt + flush bolts | Most wood and fiberglass French doors with stiles 3 inches or wider | Deadbolt, two flush bolts, reinforced strike, one visit for the pair | Our standard recommendation |
| Grade 2 single cylinder deadbolt only | Budget upgrade on an active door that already has good flush bolts | One deadbolt on a prepped door | Fine when the inactive leaf is already rigid |
| Double cylinder deadbolt | Doors that are not a required exit and have glass within reach of the thumbturn | One deadbolt, keyed both sides | Egress and fire code restrictions apply; see below |
| Surface mounted vertical deadbolt (jimmy proof) | Narrow stiles, metal doors, doors that cannot be bored | Surface lock and interlocking strike | Interlocking bolt resists prying at the seam |
| Multipoint lock retrofit | Tall or wide pairs, high wind exposure, owners who want one motion to lock three points | Hardware from Hoppe, Emtek and door manufacturers, longer install | Longer lead time on parts |
| Keyless or smart deadbolt | Rentals, pool houses, ADUs, frequent guests | Keypad or smart lock plus code setup | Choose a model with a mechanical key backup |
| Security film or laminated glass (add-on) | Any French door with glass near the lock | Priced by glass area | Keeps a broken pane from becoming an open hand hole |
Single versus double cylinder: the California question
A double cylinder deadbolt takes a key on both sides, so someone who breaks a pane cannot reach in and turn a thumbturn. It solves a real weakness. The problem is that you cannot leave in a hurry without finding the key. The California Residential Code requires that egress doors be openable from inside without a key or special knowledge, and the Los Angeles Fire Department takes the same position on exit paths. If your French doors are the only way out of a bedroom or a converted garage, a double cylinder is not the answer.
What we recommend instead: a single cylinder Grade 1 deadbolt, plus laminated glass or 8 mil security film on the lites within arm’s reach of the lock. The glass cracks but holds, the thumbturn stays out of reach, and you can still leave in the dark. Where the French doors open onto a patio from a living room that has other exits, a double cylinder is a legitimate option and we install them; we just check the room first.
Grade matters more than brand
ANSI/BHMA grades measure how many cycles a lock survives and how much force the bolt takes. A Grade 1 deadbolt has a full 1 inch throw, a hardened bolt and a reinforced housing; Grade 3 is builder hardware with a shorter throw and thinner metal. On a French door, the throw is the whole game, because the bolt has to reach through the inactive door’s edge into a strike. Schlage B60 and B660, Kwikset 980 and 985, Medeco Maxum and Mul-T-Lock Hercular are all Grade 1 and all work on French doors with a standard 2 1/8 inch bore. If you want key control as well as strength, our high security lock comparison covers the restricted keyway options.
Flush bolts: the part people skip
Flush bolts sit in the edge of the inactive door, one near the top throwing into the head jamb and one near the bottom throwing into the sill or a floor strike. Installed properly, they turn the inactive leaf into a rigid post that the active door’s deadbolt can lock against. Most French doors come with them, but on older Los Angeles homes we find bolts that were painted over, bolts with stripped screws, or bolts that were removed when a floor was refinished and never replaced. A pair of quality flush bolts is inexpensive hardware and quick to install or repair.
If your inactive door is held by a decorative surface bolt at the top only, treat it as unlocked. Add a matching bolt at the bottom at minimum.
Narrow stiles and metal doors
Aluminum and steel patio French doors, common on 1960s and 1970s houses in Culver City and Mar Vista and on newer builds, often have stiles too narrow for a standard deadbolt. Options in order of cost:
- Narrow stile deadbolt with a 1 1/2 inch or 1 3/4 inch backset. Fits many doors down to about 2 1/2 inch stiles.
- Surface mounted vertical deadbolt. Screws to the inside face of the door and interlocks with a strike on the other leaf or the jamb. Ugly to some, extremely effective against prying.
- Manufacturer multipoint lock. If the door is from a known maker, a matching multipoint kit locks at the top, middle and bottom with one handle lift. Best security, highest price, two to four week lead time.
What a professional installation includes
- Measuring stile width, thickness and existing bore before choosing hardware, so nothing is ordered twice.
- Boring the active door for a 2 1/8 inch cross bore and 1 inch edge bore if it has never had a deadbolt.
- Installing a reinforced strike or an edge strike on the inactive door with screws long enough to reach solid wood.
- Installing or repairing flush bolts and aligning the floor strike.
- Adjusting hinges and the astragal so both doors close flush; a sagging leaf is why deadbolts on French doors “stick” and eventually stop being used.
- Keying the new deadbolt to your existing house key when the keyway allows.
A pair is usually finished in one visit. Our residential locksmith team carries Grade 1 deadbolts, flush bolts and narrow stile hardware on the van, so most jobs finish in one visit. If you are choosing between a keyed deadbolt and a keypad, biometric versus traditional locks lays out the trade-offs.
Common mistakes we fix
- Deadbolt on both doors. Two keyed deadbolts facing each other cannot both throw into anything solid. One deadbolt on the active leaf plus flush bolts on the inactive is the right pattern.
- Short strike screws. The 3/4 inch screws in the box are for drywall pictures. Use 3 inch screws into the jamb, and on the inactive door use through-bolted strikes where the stile is thin.
- Thumbturn next to glass without film. A single pane of annealed glass and an unfilmed thumbturn is an open invitation. Add film or laminated glass, or reposition the deadbolt higher if the stile allows.
- Ignoring the hinges. Outswing French doors expose hinge pins. Use non-removable pin hinges or set screws in the pins.
French doors are also the door that suffers most in Los Angeles weather: sun on the south side swells and dries wood every season. Our note on temperature changes and your locks explains why a deadbolt that worked in March binds in August, and what to adjust.
When to call Locksmith Liberty
Locksmith Liberty is a licensed mobile locksmith company based in Mid-Wilshire, Los Angeles, CA, serving central and west Los Angeles including Mid-Wilshire, Koreatown, Hollywood, Beverly Grove, Miracle Mile, West Hollywood, Culver City and Santa Monica. Technicians respond 24 hours a day, 7 days a week for home, apartment and car lockouts, rekeying, lock installation and repair, car key replacement and programming, and commercial locks and access control. Every job is priced upfront before work begins. Call Locksmith Liberty any time at (213) 314-1971.
- You need a deadbolt added to French doors that never had one
- Your inactive door has missing or broken flush bolts
- You have narrow stile or metal French doors that a standard deadbolt will not fit
- You want a multipoint or smart lock on a patio, ADU or pool house door
- A deadbolt on your French doors sticks, will not throw fully, or the doors do not align
Call (213) 314-1971 or use the contact page. We dispatch fast to Mid-Wilshire, Koreatown, Hollywood, Beverly Grove and Culver City at any hour.
Serving Mid-Wilshire, Hollywood, Beverly Grove, Koreatown, Culver City and the Westside. If you are locked out of a home with the only key inside, our emergency locksmith team can open French doors without breaking glass.
French door deadbolt FAQs
What is the best deadbolt for French doors?
For most Los Angeles homes: an ANSI Grade 1 single cylinder deadbolt with a 1 inch throw on the active door, paired with flush bolts at the top and bottom of the inactive door and a reinforced strike. Installed, that package is quoted upfront as one job and closes the two weak points French doors have.
How much does it cost to install a deadbolt on French doors in Los Angeles?
It depends on the option: a Grade 2 deadbolt on an already prepped door is the least expensive, a Grade 1 deadbolt plus flush bolts on a pair is our standard package, keyless or smart deadbolts cost more, and multipoint lock retrofits are the largest job. Every quote includes the service call and is given upfront before any work begins.
Are double cylinder deadbolts allowed on French doors in California?
Double cylinder (key on both sides) deadbolts are restricted on doors required for emergency exit under the California Residential and Fire Codes, because you cannot leave without a key. Where the French doors are the only exit from a room, use a single cylinder with laminated glass or security film instead. We check egress before recommending one.
Can you put a deadbolt on French doors with narrow stiles?
Yes. Many patio French doors have stiles under 3 inches, too narrow for a standard 2 3/8 inch backset deadbolt. Options are a narrow stile deadbolt, a surface mounted vertical deadbolt on the inside face, or a multipoint lock built for the door. We measure the stile before ordering hardware.
Do I need to lock the inactive French door too?
Yes. If the inactive leaf is only held by a small latch or a surface bolt with short screws, the whole pair can be pushed open regardless of the deadbolt on the active door. Flush bolts running into the head and the sill, or a multipoint lock, are what make the pair rigid.
Can I keep the same key as my front door?
Usually. If the new deadbolt shares a keyway with your other locks (Schlage SC1 or Kwikset KW1 in most LA homes), we key it alike on site at no extra charge. If the brands differ, a small cylinder swap puts everything on one key.
