Mortise locks

A mortise bolt is a built-in bolt that you mount in the door leaf or the frame. For vertical or horizontal locking of the inactive leaf of a double door, or for additional locking of an adjoining door. We carry 10 Dulimex models in lengths of 45, 55, and 70 mm, in Silver Grey and Black, with a strike plate or strike box, and with a star key function for concealed operation.

What exactly is a mortise lock?

A mortise bolt is a concealed-mounted bolt. It is built into the door leaf so that only a small operating handle or star keyhole is visible from the outside. This works ideally for French doors (where you want to lock the inactive leaf against the frame) or for specific side doors (basement access, garage door to the garden). The bolt slides out of the door leaf into the frame recess.

For those choosing between a mortise bolt and a bolt: a bolt is vertical and has a larger operating handle; a mortise bolt is usually smaller and can operate in any direction (vertically or horizontally). For the wider boltcategory, see the complete collection.

What is a strike plate versus a strike box?

The strike plate is a flat plate on the frame side. If the bolt protrudes, it simply slides over the plate. This works fine for light locking where perfect alignment is not critical. The strike box is a recess in the frame side into which the bolt fits completely. For firmer locking and better alignment. For heavier doors or for specifically secured applications, choose a strike box.

The Dulimex mortise bolt with strike plate versions are available in 45, 55, and 70 mm. Suitable for most interior hinged door applications. The strike box versions are available in 55 and 70 mm. For those who desire stronger locking. For the 70 mm silver-grey WC set version, this is a specific combination of a mortise bolt with an integrated WC closing function.

What is a star key?

A star key is a specific key shape with a star-shaped notch. It is used for operating a mortise lock without a standard key mechanism. It is particularly useful for maintenance access (where the same star key can operate multiple locks in a building) or for specific side-door applications. The Dulimex Star Key for mortise lock DRB 3 series is the general key that fits all DRB 3 locks.

The Dulimex Mortise Bolt with star key strike plate versions (45 and 55 mm Silver-grey) are for those who want key operation for extra security. Particularly useful for garage doors, cellar doors, or specific ancillary doors where you do not want the bolt to be freely operated from the inside. For the broader mortise bolt category by finish, see mortise bolt black or mortise bolt silver-grey.

Which length for which door?

The length refers to the projection length of the bolt. How far it extends from the door leaf to fit into the frame recess. For thin interior doors or where there is limited frame depth, 45 mm works. For standard interior doors, 55 mm works. For heavy exterior doors or where you want more locking stability, 70 mm works.

An important piece of advice: measure the distance between the door edge and the frame before ordering. The bolt length must be sufficient to fill the entire gap plus at least 8-10 mm in the frame. For specific questions regarding compatibility, our advisors can provide tailored advice.

How does this fit into your door package?

A mortise bolt is for a specific locking function in addition to the main lock. For main door locking (latch lock, bathroom lock), see mortise locks. For the visible sliding bolt versions on French doors, see Sliding Bolt.

For a consistent look: choose the mortise bolt finish in the same shade as other door hardware. For silver-grey, it works visually neutrally. Matches almost any door design. For the black version, see black mortise bolt with the specific finishes. For the complete door hardwareoverview, see all elements.