How To Choose The Right Door Bolt

Introduction

Choosing the right door bolt begins with understanding what you need it to do. A bolt used to provide privacy on an internal bathroom door has different requirements from one securing the inactive leaf of a pair of French doors or holding part of a stable door closed.

You also need to consider whether the adjoining surfaces are flush or offset, whether the bolt will be fitted vertically or horizontally and whether its material and finish are suitable for internal or external use.

This guide explains the differences between surface-mounted door bolts, lever-action flush bolts, rack bolts and bathroom deadbolts. You can also browse our complete door bolt collection.

What Does the Door Bolt Need to Do?

Before choosing a design or finish, decide where the bolt will be fitted and what function it must perform.

• Internal privacy: A surface bolt can provide simple privacy on a bedroom or traditional internal door.
• Bathrooms and cloakrooms: A bathroom deadbolt with a compatible turn and release normally provides a more practical arrangement, including emergency access from outside.
• Stable doors: A surface bolt can hold the upper or lower section in position when the two parts are closed together.
• Double or French doors: Flush bolts can secure the inactive leaf at the top and bottom.
• External doors and gates: The bolt must be specifically described as suitable for exterior use and appropriate for the degree of exposure.
• Supplementary security: Concealed rack bolts may supplement a suitable primary lock, but the complete door and locking arrangement must meet the property’s security requirements.

A door bolt should not automatically be treated as the primary security lock for an entrance door. Check your insurer’s requirements and seek advice from a qualified locksmith when security is the main consideration.

Straight and Cranked Surface Bolts

Surface-mounted bolts are fitted visibly to the face of the door. Traditional designs are commonly available in straight and cranked versions.

Straight Door Bolts

Choose a straight bolt when the face of the door and the receiving surface are level. The sliding bar travels directly into a receiver bridge fitted to the adjoining surface.

Cranked Door Bolts

A cranked bolt, sometimes called a necked or offset bolt, is designed for surfaces that sit at different levels. Its shaped sliding bar crosses the offset and normally enters a mortice receiver plate fitted into the frame or adjoining surface.

Measure the difference between the two surfaces before ordering. The shape and projection vary between products, so do not assume that every cranked bolt will accommodate the same offset.

Browse our traditional hand-forged door bolts for straight and cranked designs in a range of styles and finishes.

Choosing the Correct Bolt Size

The quoted size normally refers to the nominal or overall length of the product, but the exact measurement method varies between designs. Always check the individual technical drawing before ordering.

As a general guide:

• Small bolts may suit cupboards, cabinets, shutters and lighter internal doors.
• Four-inch bolts are available for many internal-door and stable-door applications.
• Six-inch bolts provide a more substantial fitting for larger timber doors.
• Long-reach bolts make a fitting easier to operate when positioned near the top or bottom of a tall door.
• Gate and exterior bolts must have a finish specifically approved for the intended environment.

Nominal length alone does not determine strength, security or suitability. Consider the door construction, fixing material, screw length, receiver position and condition of the surrounding timber.

Lever-Action Flush Bolts

Lever-action flush bolts provide a discreet way to secure the inactive leaf of a pair of double doors. The bolt body is recessed into the door edge, reducing the amount of visible hardware when the doors are open.

These bolts can be fitted near the top or bottom of the inactive door. Operating the small lever projects the bolt into a receiver fitted to the door frame, threshold or floor.

Accurate morticing and alignment are important. The receiver must be positioned so that the bolt engages freely without forcing the door out of alignment.

View the lever-action flush bolts currently available in the Old English Collection.

Rack Bolts

Rack bolts are concealed security bolts morticed into the edge of a timber door. They are often fitted in pairs, with one positioned towards the top and another towards the bottom.

Depending on the design, a rack bolt is operated using a dedicated key or compatible thumbturn. The operating point remains visible on the face of the door while the main bolt mechanism is concealed inside it.

Rack bolts can provide supplementary security, but they must be positioned carefully to avoid weakening narrow door stiles, damaging glazing or interfering with an existing lock. Always follow the product measurements and fitting instructions.

See our current rack bolts and coordinating thumbturns.

Bathroom Deadbolts

A bathroom deadbolt is a compact morticed mechanism fitted inside the edge of an internal door. It is operated by a separate bathroom turn and release.

The thumbturn on the inside projects the bolt into the strike plate. The external release allows the door to be unlocked in an emergency, usually with a coin or similar flat object.

A bathroom deadbolt does not operate the door handle or knob. When the door also needs to latch closed, the handle or knob normally operates a separate tubular latch.

Alternatively, a bathroom sash lock combines the latch and privacy bolt in one morticed lock case. Compatibility depends on the selected door furniture, spindle sizes, backset and fixing centres.

Browse our tubular latches and bathroom deadbolts, including the 2.5-inch bathroom deadbolt.

Bolts for External Doors and Gates

Only use a bolt outside when its product description confirms that the material and finish are suitable for exterior use. Standard black beeswax and pewter hand-forged bolts are intended primarily for interior applications.

Armor-Coat Door Bolts

Door bolts with Armor-Coat have a specialist UV- and rust-resistant finish and are suitable for internal or external use. They are available in straight and cranked versions and in 4-inch and 6-inch sizes.

Tudor Door Bolts

Tudor door bolts are made from black powder-coated cast iron. They are suitable for interior and exterior use but are not recommended for coastal locations.

Exterior hardware should still be inspected regularly, especially around moving parts, screw holes and areas where friction could damage the protective coating. Coastal locations need particular care because salt carried in the air accelerates corrosion.

Browse our outdoor door and gate bolts for products designed for external applications.

Door Bolt Safety and Security

A correctly chosen bolt should suit the door’s purpose without creating an avoidable safety problem.

• Avoid fitting an internal surface bolt where a young child could lock themselves inside without an emergency means of access.
• Do not rely on a small privacy bolt as the primary security lock for an external entrance door.
• Do not fit a bolt to an escape door if it could prevent occupants from opening the door quickly in an emergency.
• Make sure the receiver is fixed into sound timber or another suitable structural surface.
• Do not position morticed bolts where they could weaken a narrow door stile or interfere with glazing.
• Check your insurer’s requirements before changing the primary locks on an external door.
• Ask a qualified locksmith or experienced joiner for advice if security, fire safety or accessibility is uncertain.

Whichever design you choose, check the product dimensions and supplied components before drilling or cutting the door.

Choosing the Right Bolt

Start by identifying what the bolt must do and where it will be fitted. A traditional surface bolt may suit an internal bedroom, cupboard or stable door, while a bathroom deadbolt provides privacy with an external emergency release.

For double doors, a recessed lever-action flush bolt can secure the inactive leaf. Rack bolts can provide supplementary concealed restraint, while exterior doors and gates require a bolt with a finish specifically approved for outdoor use.

Finally, confirm whether the fitting surfaces are flush or offset, then compare the product dimensions with the available fixing area. This will help you choose between straight and cranked designs without relying on nominal size alone.

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Related Reading

• Traditional Hand-Forged Door Bolts – Cast Iron & Armor Coat Options for Outdoor Use
• How To Fit A Tubular Latch
• How to Lock Your Suffolk Latch

Frequently Asked Questions

What is the difference between a straight and cranked door bolt?

A straight bolt is used when the door and receiving surface are level. A cranked bolt has an offset shape and is intended for surfaces that sit at different levels.

What size bolt should I use on an internal door?

There is no universal size for every internal door. Smaller bolts may suit cupboards and lightweight doors, while 4-inch or 6-inch bolts may suit larger doors. Check the technical drawing, door construction, fixing area and intended use before ordering.

Can a door bolt be fitted vertically?

Some spring-tensioned bolts can be fitted vertically or horizontally without the slider dropping. Check the individual product description because not every bolt is designed for both orientations.

Can I use an internal door bolt on a garden gate?

No, unless the product information specifically confirms that its material and finish are suitable for exterior use. Internal finishes can corrode when exposed to rain, condensation and changing temperatures.

Is a bathroom deadbolt the same as a surface bolt?

No. A bathroom deadbolt is morticed into the door and operated by a turn and release. A surface bolt is fixed visibly to the face of the door and normally has no external emergency release.

Are door bolts secure enough for a front door?

A bolt may provide supplementary restraint, but it should not automatically be treated as the primary security lock. Use an appropriate locking system and check your insurer’s requirements.

What is a flush bolt used for?

A flush bolt is commonly used to secure the inactive leaf of a pair of double doors. The mechanism is recessed into the door and engages with a receiver in the frame, threshold or floor.