Deadbolt Types Explained: Which One Belongs on Your Door

Updated November 8, 2026 by Tim's Locksmith Service

What type of deadbolt should you buy? For most exterior doors, a single cylinder deadbolt with a full 1-inch bolt throw, a reinforced strike plate, and long screws into the framing is the right answer. Double cylinder, keypad, smart, vertical, and mortise deadbolts each solve a specific problem, but none of them make up for a weak strike or a soft door frame. The type decides how you lock and unlock. The installation decides how well the door holds.

This guide walks through each type, what it is good at, where it causes trouble, and how to choose for a front door, a door with glass, and a rental.

Single Cylinder: The Standard for a Reason

A single cylinder deadbolt takes a key on the outside and has a thumb turn on the inside. It is what most homes have on the front door, and for most doors it is the right choice. You lock it with one twist on the way to bed, and anyone inside can get out fast in a fire or emergency without hunting for a key.

The weak point people worry about is the thumb turn. If there is glass in or beside the door within arm's reach of it, someone can break the glass, reach in, and turn it. On a solid door with no glass nearby, that concern does not apply, and a quality single cylinder deadbolt is hard to beat.

Double Cylinder: Key on Both Sides, With a Fire Safety Tradeoff

A double cylinder deadbolt needs a key on both sides. Breaking the glass and reaching in gets a burglar nothing, because there is no thumb turn to grab. On a door with a glass panel or sidelight, that is a real benefit.

The tradeoff is getting out. In a fire, at night, in smoke, you need that key in your hand to open the door. Building and fire codes generally require the main exit door of a home to open from the inside without a key or special knowledge, and many jurisdictions restrict double cylinder deadbolts on that door for exactly this reason. Rules vary and change, so check with your local building department before installing one.

If you already have one, keep a key on a hook near the door, out of reach from the glass, and make sure everyone in the house, including kids and guests, knows where it is.

Keypad and Smart Deadbolts

Keypad deadbolts replace the outside key with a code. Most are electronic and run on batteries, and a few are mechanical push-button models that never need power. Smart deadbolts add a motor and a connection to your phone, so you can lock remotely, get alerts, and hand out codes that expire.

The convenience is real: no keys to lose, no copies floating around, and codes you can change in seconds. But under the electronics it is still a bolt, a strike, and a door, and the same strength rules apply. Most keypad and smart deadbolts keep a thumb turn inside, so they carry the same glass concern as a single cylinder. Many keep a backup keyway too, which needs rekeying like any other cylinder. Our smart lock buying guide covers connectivity, batteries, and door prep.

Vertical and Mortise Deadbolts

Vertical (jimmy-proof) deadbolts

A vertical deadbolt mounts on the inside face of the door, with a matching strike on the frame. Instead of sliding sideways, its bolt drops down through interlocking rings on the strike, locking door and frame together.

That makes prying the door away from the frame much harder, which is why you see them on apartment doors, doors that swing outward, and as a second lock above a standard deadbolt. Because it is surface mounted, its strength comes down to the screws and what they bite into.

Mortise deadbolts

A mortise lock sits in a deep rectangular pocket cut into the edge of the door, often with the latch and deadbolt in one heavy case. You find them in older homes, including plenty of bungalows in both counties, in high-end entry sets, and in commercial buildings. Built well, they are strong and last for decades. The catch is parts. Older mortise bodies can be hard to match, and converting a mortise door to a standard deadbolt takes filler plates or woodwork. Have a locksmith look before you buy a replacement.

What Actually Makes a Deadbolt Strong

Shoppers compare finishes and features. A kick or a pry bar tests something else entirely. In order of what matters:

• Bolt throw. Look for a full 1-inch throw. A shorter bolt leaves less steel in the frame. A deadbolt also only deadlocks when it extends all the way, so if the strike hole is shallow or misaligned and the bolt stops short, it can sometimes be pushed back.
• The bolt itself. Better deadbolts have a hardened steel insert or a free-spinning pin inside the bolt to resist sawing.
• Strike plate and screws. When a door is kicked, the frame usually splits before the bolt bends. A heavy strike with 3-inch screws into the wall framing is the biggest upgrade most doors can get. Our lock grades guide covers strikes and ANSI grades in depth.
• Door and frame condition. A hollow-core exterior door, a cracked jamb, or a wide gap between door and frame undercuts any lock. A wrap-around reinforcer plate helps a door whose edge is split or weak around the lock.

How to Choose: Front Door, Glass Door, Rental

Front door

A Grade 2 or Grade 1 single cylinder deadbolt, a reinforced strike with long screws, and the same key as your other exterior doors. If you want keyless convenience, a keypad or smart deadbolt works, as long as the bolt and strike meet the same standard. Tim handles deadbolt installation across both counties and reinforces the strike on the same visit.

A door with glass in it or beside it

You have three honest options. Keep a single cylinder and make the glass harder to get through with security film or laminated glass, which turns a quick smash into a slow, noisy job. Use a double cylinder where your local code allows it, with the key on a hook out of reach from the glass. Or look at deadbolts with an inside thumb turn that can be locked or removed when you leave, which keeps a key-free exit while you are home. Check that option against local code too.

A rental

For a long-term or vacation rental, single cylinder deadbolts keep emergency exits simple. Keypad deadbolts make turnover easy, since you change the code instead of collecting keys, but rekey the backup keyway between tenants too. Avoid double cylinders on rental units unless your local building department has confirmed they are allowed. Tenants have their own questions about who controls the locks, covered in our guide for renters.

We serve Ventura County including Oxnard, Ventura, Thousand Oaks, Simi Valley, Camarillo, and San Diego County including San Diego, Chula Vista, Oceanside, Carlsbad, Escondido.