Montclair, San Bernardino County
Double Cylinder Deadbolt Installation in Montclair
Short answer: Both cylinders are keyed alike, so one key works the lock from either side. Installation uses the standard 2-1/8-inch and 1-inch bores, but the interior cylinder needs clearance and a plan for where the key lives. Julian's Locksmith handles double cylinder deadbolt installation in Montclair, talks through exits and the key plan, and quotes before starting. Call (951) 903-3193.

Someone told you a double cylinder deadbolt is illegal. Someone else told you it's the only way to protect a glass door. Both are partly right. Building codes in California expect the required exit door of a home to open from inside without a key, so a double cylinder doesn't belong there. Other doors, such as a shop, a mudroom with another exit available, or an interior storage room, are a different story. Julian's Locksmith installs double cylinder deadbolts in Montclair where they're appropriate and talks you through the rules for the door you actually have. Call (951) 903-3193.
Double Cylinder Deadbolt Installation in Montclair: what to expect
Codes and common sense point the same way on exits. California's residential code expects the required exit door of a dwelling to open from the inside without a key, special knowledge or effort. Commercial codes carry similar rules, with narrow exceptions for certain occupancies that depend on signage and conditions. Local building and fire departments interpret and enforce these, and on existing homes enforcement usually surfaces during an inspection, a remodel or a sale. Insurers and landlords differ too. The safety logic doesn't wait for an inspector, though. Our rule is simple: we won't put a keyed-both-sides lock on the door your household relies on to get out in a fire. Secondary doors, outbuildings and interior storage rooms are different, and we install double cylinder deadbolts there after talking through the exit plan with you and confirming that another way out exists. You hear our reasoning in plain terms before any drilling starts.
What we can do on-site
- Double cylinder deadbolt installation on glass-panel doors. Glass within arm's reach of a thumbturn is the classic reason for a double cylinder. If the door and its use suit it, we install the lock, confirm the stile is wide enough for the bore, and set the cylinders square so the key turns without binding. Then we agree on where the key will live.
- Exit and code check before we drill. Before drilling, we look at where occupants would leave in a fire, whether this door is the main route, and who lives or works inside. Building and fire codes drive the answer, and local departments enforce them differently. We won't fit a lock that traps people, and we say so before quoting.
- Interior storage rooms and secured closets. Not every locked door is an exit door. For pantry-style storage, equipment rooms and similar interior spaces, a double cylinder is a sensible choice. We install it on a solid frame, check clearances at the cylinder, and tell you honestly if a keypad lock or a single cylinder suits you better.
- Keying, spare keys and the key plan. Because one key does everything, how you store it matters as much as the lock. We suggest a spot near the door but away from the glass, and a spare in a separate place. For households with kids or older relatives, we plan more carefully so nobody has to hunt in an emergency.
- High-security and restricted-key double cylinders. If the key to a keyed-both-sides lock gets copied by a former tenant or contractor, the lock is only as good as that key. A restricted-key cylinder makes copying harder. We can fit one, set up the key card and explain how authorized copies work.
How Montclair shapes the job
Older homes in Montclair frequently have wood doors with divided glass panes close to the lock, and some already carry a double cylinder from a previous owner. These doors are often the main exit, so we usually recommend a strong single-cylinder deadbolt and laminated glass in the pane nearest the lock. For a rear door that isn't the main route, a double cylinder can make sense. We check stile width before drilling, since old wood can split.
In family neighborhoods across Montclair, kids, guests and busy mornings make a key-to-exit lock hard to live with. Children can't always find or turn a key, and visiting grandparents have never seen it. For the front and garage-entry doors we recommend single cylinders. A double cylinder can work on a detached garage door or a storage room where nobody needs a quick way out.
Apartment tenants in Montclair often ask about double cylinders after a break-in on a balcony or glass door. In a rental unit, the main entry must keep working deadbolt hardware under California law, and tenants need to leave without a key in an emergency. We usually recommend reinforcing the strike, protecting glass and asking the landlord to approve any lock changes. Landlords can call us to remove an unauthorized double cylinder at turnover.
Situations this covers
- A bungalow has a brass mail slot cut into the front door about eight inches from the deadbolt's thumbturn. The owner has read that a hooked wire fished through a slot can turn some thumbturns. A double cylinder would solve it but trap the household. We suggest sealing or relocating the slot, using a catch box, or mounting the deadbolt higher, and keep a normal thumbturn on the door.
- A seller in Montclair learns during escrow that the buyer's inspector flagged the double cylinder on the front door as a safety concern. The key has been missing for years. We replace the lock with a single-cylinder deadbolt of the same brand, rekey it to match the garage entry, and give the agent a short note of what changed. The sale carries on without the issue.
- A family off Benito Street has a mudroom door with a window beside the lock that opens to the side yard. The front door is their main exit, and the mudroom is rarely used to leave. After checking, we install a double cylinder deadbolt and hang a labeled key hook on the wall near the door, out of reach from the window and visible to everyone in the house.
- A 1920s Craftsman near Montclair Transit Center has a front door with nine small glass panes and a thumbturn deadbolt six inches from the nearest pane. The owner asks for a double cylinder. We explain that this is the home's main exit, so a lock needing a key to leave conflicts with exit guidance. We install a strong single-cylinder deadbolt with a box strike instead, and she calls a glazier about laminated glass for the pane nearest the lock.
From your call to the finished job
- Talk through the door and the reason. We begin by listening: what happened or what worries you, how the household uses the door, who lives there. Break-in history, kids, older relatives and guests all matter. Then we give an honest arrival estimate and explain what we'll check when we get there.
- Check exits, glass and the people involved. We measure how far the glass is from the lock, test whether a hand could reach it, and note who uses the door. That tells us whether the double cylinder really adds security or only adds risk. You get a plain recommendation and the reasoning behind it.
- Measure, quote and choose the hardware. We measure door thickness, backset and stile width, then pick a deadbolt that fits: standard thickness, a thick-door kit or a narrow-stile alternative. You see grade and finish options and get a quote before any hole is drilled.
- Prepare the door. Doors with glass need careful drilling. We mask the panes, clamp the jig, cut a clean 2-1/8-inch bore and a 1-inch edge hole, and check that nothing intrudes on the glass stop. Wood chips and dust are cleaned up before we mount anything.
- Fit both cylinders, key them and set the strike. We mount the bolt, then fit the exterior and interior cylinders through the tailpiece, aligned so the keyway sits upright when unlocked. Both are keyed alike to your key. Then the strike goes in: a box strike with 3-inch screws into the framing.
- Test the lock and plan the key. The visit ends with an actual drill: door locked, key at the planned spot, you walking from the far side of the room. If that feels slow, we rethink the plan or the lock. We hand over keys and note the keyway and brand for your records.
Pricing factors
- Door prep and thickness. Fresh drilling takes more time than a swap in existing holes. Hollow or damaged doors may need reinforcement, and thick or custom doors need special kits. The more unusual the door, the more prep time, which is why we look before quoting.
- Strike and frame reinforcement. A box strike with 3-inch screws is a small hardware cost. A split jamb, rotted frame or loose hinge side is a larger one. Glass doors often sit in lighter frames, so reinforcement matters, and we price it as its own line so you can see it.
- Glass protection you add separately. Protecting the glass is often the better fix, and it is priced apart from our visit. We don't install glass or film, so we explain what to request from a glazier and quote our own part clearly. That keeps the two jobs, and the two costs, from getting mixed together.
Every job gets a clear quote before any work starts. Call (951) 903-3193 with the details and we'll tell you what to expect for your situation in Montclair.
Advice before you book
- Match the lock to your door thickness. Most double cylinder deadbolts expect 1-3/8 to 1-3/4 inches. Thicker doors need an extension kit, and kits are model-specific. Measure the door edge rather than the frame, and photograph the existing bores. We can bring the right kit if you give us the number.
- Don't count on a spare key under a mat or in a flowerpot for a keyed-both-sides door. It's the first place a burglar looks, and it doesn't help anyone leaving from inside. Leave the spare with a trusted neighbor or relative, or in a lockbox with its own code.
- Check your insurance and local rules before installing. Policies, leases and HOA rules differ, and we can't speak for your carrier. A short call to your insurer and to the local building or fire department can prevent trouble at renewal, at inspection or when you sell the house.
- For an outbuilding, put the key on your main ring and a spare in the house. No one sleeps there, so exit planning is simple, but a lost key can lock you out of your own tools. Keying it alike with your other locks keeps the ring lighter.
Mistakes to avoid
- Using a double cylinder on a bedroom or an only-exit door. Bedrooms and the only route to an exit need to open without a key. A keyed-both-sides lock there can trap people, especially kids, during a fire, a medical emergency or an ordinary lockout from the wrong side.
- Skipping the strike. People focus on the interior cylinder and leave a thin strike held by short screws. A hard kick pops a short-screwed strike out of the jamb, and the double cylinder never gets a chance. Fit a box strike with 3-inch screws into the framing at the same visit.
- Putting a double cylinder on the main exit and hiding the key far away. In a fire, that costs seconds nobody has. Households do it because a pane of glass worries them. Protect the glass instead and keep a normal thumbturn on the door your family relies on to leave.
Service in Montclair
Montclair is about 29 miles from our San Bernardino base, roughly 36 minutes in light traffic via Belmont Ave and Palm Ave to I-215 North, I-15 South past Fontana and Rancho Cucamonga. When you call, you get an arrival estimate based on where the technician is and the traffic at that moment.
We plan the drive the way a delivery route gets planned: freeway first, Mills Avenue where it makes sense, then the side streets you describe. A landmark or the color of your building helps the technician spot you.
About Montclair: A planned extension of Metro's A Line light rail to the Montclair Transit Center was put on indefinite hold in 2025 after San Bernardino County transportation officials redirected its funding.
| Neighborhoods | Arrow Highway corridor, North Montclair, Central Avenue corridor, Civic Center, Monte Vista Avenue corridor, Mills Avenue area |
|---|---|
| ZIP codes | 91763 |
| Main routes | I-10, Central Avenue, Monte Vista Avenue, Mills Avenue |
| From our San Bernardino base | about 29 miles via Belmont Ave and Palm Ave to I-215 North, I-15 South past Fontana and Rancho Cucamonga, then I-10 West to the Monte Vista Avenue or Central Avenue exit; SR-210 West to Monte Vista Avenue, then south, for North Montclair |
New or replacement locks in Montclair?
Call (951) 903-3193 and tell us which doors and what kind of hardware you have in mind. If you already bought the lock, keep the box handy so we can check it fits the door, and we'll quote the install before any work starts.
Frequently asked questions
Can I use a double cylinder deadbolt on a business door?
Commercial codes require exit doors to open without a key in most cases, with narrow exceptions for particular occupancies and signage. Your building department or fire marshal decides what applies. We install keyed-both-sides locks on back-of-house rooms and non-exit doors, and use code-compliant hardware on exits. Call (951) 903-3193 with the door's use and we will help sort it out.
How much does double cylinder deadbolt installation cost?
It depends on the lock grade, whether the door is already bored, door thickness, strike reinforcement and how many keys you want. A double cylinder on a prepared door is a simpler job than fresh drilling through glass-panel wood. Call (951) 903-3193 with the details and we'll give you a quote before we start.
How long does installation take, and when can you come?
A double cylinder on a door that's already bored is a short visit, and fresh drilling on a glass-panel door takes longer. We work every day from 6:30 a.m. to 11:30 p.m., weekends included. Call (951) 903-3193 and we'll give you an honest arrival estimate for Montclair.
Will a double cylinder deadbolt fit my French doors?
Maybe. The stile needs enough solid material for a 2-1/8-inch bore and a 1-inch edge hole, roughly 3-1/2 inches or more, plus room beside the glass stop. Many wood French doors qualify, while narrow aluminum or steel frames usually don't and need a different lock. French doors are often a required exit, which also matters. We measure before recommending anything.
Is a double cylinder more secure than a single cylinder?
Only against one attack: breaking glass and reaching in to turn the thumbturn. Against kicks, prying, picking or drilling, the bolt, strike and frame decide the outcome, not the cylinder on the inside. If no glass sits within arm's reach of your lock, a good single-cylinder deadbolt with a reinforced strike is just as secure and safer to live with.
Can you replace my existing double cylinder with a single cylinder?
Yes. The bores are the same, so we remove the double cylinder, install a single-cylinder deadbolt with a thumbturn inside and key it to your house key if you like. It's a quick swap. We can also strengthen the strike and talk about protecting the glass so you aren't trading security for safety.
How far is Montclair from your base?
Montclair is about 29 miles from our San Bernardino base, roughly 36 minutes in light traffic. Arrival time depends on traffic and on the job the technician is finishing, so we give you an estimate on the phone before you commit.
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