Deadbolts · explained · Manchester
A latch keeps the wind out. A deadbolt keeps people out.
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- Fitted £45-140
- 30-60 min
- BS3621 available
- Free advice first
Two bolts can come out of the edge of your door and they are not the same animal. One springs. One does not. Almost everything about door security comes down to knowing which one is actually holding your door shut at night.
Latch versus deadbolt
Latch
Angled face, spring behind it. Pushes back when the door closes, then pops out. Holds the door shut. Can be pushed back in. That is the credit card trick, and it works because a latch is a spring.
Deadbolt
Square end, no spring. Only a key or a turn moves it. Nothing pushes it back, nothing slips it, and there is no angled face to work against. That is the whole point.
Your front door probably has both: a nightlatch that clicks shut, and a deadbolt you have to deliberately lock. If you shut the door and walk away without turning a key, you have a latch holding your house.
Single, double, and the one that can kill you
| Type | Inside | The trade-off |
|---|---|---|
| Single cylinder | Thumbturn | Always get out. But glass near the door means an arm can reach the turn. |
| Double cylinder | Key needed | Nothing reaches through glass. But in a fire, no key means no exit. |
This is a genuine safety decision, not an upsell. A double cylinder deadbolt on a door where the key is not kept within reach is a hazard. People have died in house fires hunting for a key in the dark. If you fit one, the key lives on a hook beside the door, at adult height, out of arm's reach of the letterbox and any glass. Every time.
If that sounds like a lot of remembering, fit a single cylinder and deal with the glass a different way: laminated glazing, or a security upgrade that does not depend on you finding a key while the hall is full of smoke.
Which door needs what
- Wooden front door: BS3621 mortice deadlock, £85-140
- Wooden back door: same. It is the one they'll try.
- uPVC / composite: the deadbolt is already in the multipoint
- Flat, escape route: BS8621, thumbturn, no key to leave
If you live in a flat, a double cylinder deadbolt may breach your fire risk assessment even if your insurer asks for BS3621. That conflict is real and BS8621 usually resolves it. See BS3621 explained.
Throw length
How far the bolt travels matters more than the brand. A short bolt only has to clear the frame edge for the door to be kicked open. A proper deadbolt throws far enough to sit deep in the frame, and it wants a decent strike plate with long screws going into the stud, not the 20mm ones in the box.
A good lock in a soft frame is a good lock in a soft frame. Half the failures we see are the timber giving way, not the lock.
Mortice locks · Lock change · Burglary repair
Questions people actually ask
What's the difference between a deadbolt and a latch?
A latch has an angled face and a spring behind it, so it pushes back when the door closes and pops out again to hold it shut. Because it is sprung and angled, it can be pushed back in, which is what the credit card trick exploits. A deadbolt has a square end and no spring at all: only a key or a thumbturn moves it, nothing pushes it back and nothing slips it. Your front door probably has both. If you shut the door and walk away without turning a key, only the latch is holding your house.
Should I get a single or double cylinder deadbolt?
It depends on whether there is glass near the door, and it is a safety decision rather than an upgrade. A single cylinder has a thumbturn inside so you can always get out, but if there is glass in or beside the door, someone can break it, reach in and turn it. A double cylinder needs a key from both sides so nothing reaches through, but in a fire, no key within reach means no exit, and people have died in house fires looking for one. If you fit a double, the key lives on a hook beside the door at adult height, out of arm's reach of the letterbox and any glass, every single time.
Does my uPVC door need a separate deadbolt?
No. Your uPVC or composite door already has one built into the multipoint mechanism: when you lift the handle and turn the key, one of the points that throws is a deadbolt, alongside the hooks and rollers. Fitting a separate deadbolt to a uPVC door is not normally possible or sensible. What matters on those doors instead is the euro cylinder, because that is the weak point, and whether it meets TS007 3-star or SS312 Diamond.
How much does it cost to fit a deadbolt in Manchester?
A BS3621 5-lever mortice deadlock supplied and fitted to a wooden door is £85 to £140 and takes 30 to 60 minutes. A non-BS3621 deadlock is £45 to £90, but if your insurer asks for BS3621 you would be paying twice. For a flat on an escape route, a BS8621 lock with a thumbturn is £95 to £150. There is no call-out fee and the price is fixed before we start.
Is a longer bolt actually better?
Yes, and it matters more than the brand name. A short bolt only has to clear the edge of the frame for a good kick to open the door. A proper deadbolt throws far enough to sit deep in the frame, and it needs a decent strike plate fixed with long screws going into the structural stud rather than the 20mm ones that come in the box. Half the door failures we attend are the timber giving way rather than the lock, so a good lock in a soft frame is still a soft frame.