Internal Door Locks Explained: Latch, Bathroom and Sash Lock Kits

Buying door handles for a whole house, the style question is easy — the function question is where people get stuck. Every internal door needs one of three mechanisms, and choosing the right one per room at the start saves re-buying later. This guide explains all three in plain English.

1. The Latch: Doors That Just Open and Close

A tubular latch is the spring bolt the handle operates — push the lever, the bolt retracts, the door opens. No locking of any kind. This is the right mechanism for most doors in the house: living rooms, kitchens, landings, most bedrooms. A latch kit bundles the lever pair with a correctly sized latch; latch-and-hinge sets add hinges for newly hung doors.

2. The Bathroom Lock: Keyless Privacy

A bathroom lock adds a deadbolt thrown by a thumb turn on the inside — no key to lose, operable with wet hands — and an emergency release on the outside, turned with a coin, so a locked-in child is a thirty-second problem rather than a removed-door problem. This is the standard for bathrooms and WCs, and increasingly for main bedrooms too. Complete sets live in bathroom door lock sets.

3. The Sash Lock: Locking With a Key

A sash lock combines the everyday latch with a separate key-operated deadbolt in one case. The door works normally all day; turn the key and it is properly locked. Home offices with client paperwork, studies, storage rooms and any room where you control who unlocks it — that is sash lock territory. Keys come with the set; see door handles with lock and key.

One Look, Three Functions

The trick is choosing a handle range that exists in all three functions. Our Hera, Lumina, Spectra and Solace ranges each come as plain latch pairs, bathroom kits and sash lock sets in identical finishes — so the landing looks uniform while the WC quietly locks with a thumb turn and the office locks with a key. Compare finishes from the door handles hub: matt black, antique brass or satin nickel.

Replacing vs First Fitting

Replacing like for like is simple — UK lock cases follow standard sizes, so a new bathroom lock usually drops into the old mortice. Changing function (a plain door becoming a locking one) means enlarging the mortice pocket: a careful chisel job for a confident DIYer, twenty minutes for a joiner. The levers themselves fit the existing spindle hole either way.