Which lock? Mortice self deadlock....

23 Feb 2005
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United Kingdom
Gonna replace a lock on a back door, currently has a standard mortice deadlock but would like to swap this over for a self-deadlocking type, like a nightlatch on a front door.

What would be the best lock for the job?

How to enable the handle to open from the inside, but disable it from the outside, so only the key can get you in?

The door is timber, half-glazed.
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the Chubb 3R35 works like that.

It is not very cheap.

You can double-lock it, whereupon the handle is also locked (so, e.g. if someone smashes the glass they can't open it by turning the handle)

You will find one on the front door of almost every High Street bank, and my house.

It is a large mortice lock.

It has the Chubb 5-detainer mechanism, and you can have it suited with other locks in that range (e.g. with the deadlock on your front door) so you can open them all with the same key.

It is quite an old design, and although it is very strong and resistant to picking, it does not have the BS Kitemark. the heavy steel latch does not protrude as far as modern BS locks, so you need the door and frame to be a good close fit (if not, you may be able to take up the gap by not recessing the staple into the frame)

On a back door it is usual to supplement the lock with Rack Bolts top and bottom.

Here is a pic of one opened up for inspection, also the special handle set (you don't have to use this, you can fit an ordinary knob inside, but the special handle includes a snib to hold back the latch to prevent the door locking itself if e.g. it blows shut while you are getting the milk in.

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If you want to buy one I might be able to help.
the Yale PBS1/2 is what your after.Dot buy the ERA version,it is much cheaper than the Yale but poor quality with a couple of issues.
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as you say johnd,the 3r35 is not to bs3621 so wouldnt be suitable for insurance purposes,assuming that is a requirement?.i would leave the mortice lock in situ and fit a bs3621 rated nightlatch in addition to the mortice lock
Thanks for pointers guys. The door is a tradesmen's/back entrance into a block of flats. Each flat has it's own decent door security, but the people living there currently have a standard handle latch, and a deadlock which is operated by a key either side to get in/out.

They are finding it a PITA having to lock the door behind them when they go out, and then forgetting to lock it when they come back in. The door leads onto the car park at the back of the block so they are in/out quite a lot.

It might just be easier and cheaper to fit a normal nightlatch.

I'll look into those others though, cheers.

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