Fitting a mortice door bolt

Mortice door bolts fit in the edge of doors providing an excellent extra security measure. Normally, bolts are positioned on the opening edge of the door – one close to the top of the door and another close to the bottom. They may also be used on the hinging edge. The bolts are key operated from the inside, and cannot be accessed from outside.

door edge bolt 1. Mark the bolt position on the door edge and then drill a hole to the depth of the door bolt as directed by the manufacturer. Either a flat wood bit or auger bit is ideal for this. You can also mark the depth requirement with a piece of tape on the bit to know exactly how far in to go.
insert door bolt 2. Insert the bolt and mark a line around the outside edge of the end plate.
chisel out for door bolt 3. Remove the bolt and, using a chisel, carefully remove enough wood from within the pencil outline for the door bolt end plate to be neatly recessed.
marking keyhole 4. Hold the bolt against the inside face of the door, and accurately mark the position of the keyhole with a bradawl.
drill hole for bolt 5. Using a drill bit size recommended by the manufacturer, drill a hole through to the hole for the bolt. Do not drill right through the door!
drill pilot holes 6. Reposition the bolt and use a pencil to mark the fixing positions. Remove the bolt once more and drill pilot holes for the fixings. A 2-3mm wood bit is an ideal size for the pilot holes. Slide in the bolt and fix it in place.
fit key plate 7. Drill further pilot holes before fixing the key plate in place. The plate must be correctly aligned with the keyhole.
bolt key 8. Check that the key works. You can then turn you attention to drilling a hole for the bolt in the frame. It is best to shut the door and gently turn the key until it touches the door frame. Most bolts have a small nib in the centre that provides a small mark on the frame. Therefore you simply re-open the door, and the mark provides you with the precise position to drill the hole for accommodating the bolt. Once drilled to size and depth, as per the manufacturer’s guidelines, use a similar technique to that shown in step 3, in order to recess the mortice plate. This may then be fixed in position, and the mortice bolt is then ready for use.

Door bolt tips

  • Mortice door bolts provide excellent security, but if you prefer not to get involved with drilling and chiselling, you can always fit some surface mounted bolts. Other easily fitted door security include such fittings as door chains and limiters – both these options are again, surface mounted.
  • The type of mortice bolt shown above may also be used in the edge of the opening sections of wooden windows, as long as the window edges are flat in design.


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