Normally consumers want to replace such lock because they
1. Lost the key
Change the key cylinder will do from $80 onwards depend on the type of key you used
2. Handle broke or turned loose
Purchase the handle will do. Note: there are hollow, semi solid and full solid. Normally the cheaper ones are the hollow ones
Cost $80-150
3. The ledge is faulty
If your door cannot close properly there are 2 possible reasons
3.1 The ledge is rusty or too stiff, which prevents your door from closing completely at times, spray the WD40 onto it and it will improve the situations
3.2 The strike plate from your door frame have door alightment issue, hence it have damage the ledge
In order to change the ledge, you need to replace the entire mortise as it comes in a set. Cost $150-200
Replace a New Set of European Mortise
If you want to replace the entire lock, you need to take down the below 3 measurements
1. Distance from the edge of the door to the center of the handle
2. Distance from the center of the handle to the key cylinder
3. thickness of the mortise and your door
Hollow handle Mortise set cost $250-300 for supply and install ( low quality)
Semi Solid Mortise Set Cost $300-350
Full Solid Mortise Set Cost $350-450
Method 1 - Install Above the Existing Lock
Otherwise, you will have to spend money to replace both mechanical lock and to install a new digital lock which is not practical
Veneer door should not have issue to install a digital lock above it as it has a smooth surface
However, for those classic HDB door with boxes perturbing out of the surface. We need to chisel the pattern so that the digital lock can fit into the design as shown below
Method 2 - Replace with a Samsung or Yale Mortise Digital Lock
HIGHLY RECOMMENDED!!!!!!
On top of that, Samsung have developed a double lock mortise which is slightly bigger than the usual European mortise.
After replacement, you can hardly see any scars leave behind.
The best solution and perfect replacement. Its either sooner or later you will upgrade your traditional mechanical lock to these awesome keyless solution