Knowledge base · Technical note
Overlock vs lockout for vacant and overdue units
Every facility does this job, and almost nobody documents how. The hardware is simple; the operating rule around it is what causes problems.
The difference in one paragraph
An overlock is a physical plate or bracket that covers the existing hasp or lock so the unit cannot be opened even with the tenant's own key. A lockout is the broader practice of denying access — the hardware depends on the door and the lock already fitted. Overlock hardware is one way to implement a lockout; it is not the only one.
When an overlock plate is the right tool
- The tenant lock is still on the unit and cannot be removed
- You need the block to be visibly obvious, not subtle
- You want to restore access without replacing any lock
- Entry without the tenant's cooperation is required
Overlock plates suit standard hasp unit doors and most roll-up doors.
The fit problem nobody warns you about
An overlock plate has to clear two things as the door moves: the lock body and the door track. A plate that clears the lock but catches the track will prevent the door from closing, which turns a security measure into a maintenance call.
That is why the plate is test-fitted on a real door before the order is confirmed. It is the most common reason an overlock does not work in practice.
Keying the overlock
If a manager key is going to operate the overlock, plan that keying with the unit cylinders in the same schedule. Planning them separately is how a facility ends up with a manager key that opens the units but not the overlocks.
Write the operating rule down
The hardware is the easy part. Document:
- What triggers a lockout (days overdue, notice served, management decision)
- Who is authorised to apply and remove it
- Where the action is recorded
- What the tenant is told, and how
Without that, the same situation gets handled three different ways by three different staff members.
Confirm it on your own doors
Send a door photo, the cylinder size or the mounting dimensions. We confirm fit with a physical sample before you commit to a quantity.
What readers ask next
Choosing the hardware is the easy half.
Can the overlock be keyed to our existing site key?
Yes, if the keying plan covered it when the first order was placed. Send the existing key plan and we will confirm whether the overlock sits on it or needs its own.
How many overlocks does a facility need?
Enough to cover the units that can be vacant or overdue at the same time, plus spares. Send the unit count and the typical vacancy pattern and we will size it with you.
Who should hold the overlock key?
That is a site policy decision rather than a hardware one, and it belongs in writing next to the key plan. We supply the hardware and the keying record; the rule that governs its use is yours.