Fitting mortice lock to internal door - query

[RrogerD]

I'm planning on using a half-glazed internal door as an 'external' door. I say external but it is in fact still internal in so far as it opens into a conservatory / lean-to area. The conservatory will still have a proper, thicker, external door.
I want to fit a decent security lock to this internal door in the form of a 5-lever night latch. edit: mortice sash lock
My query is: will the door thickness be ok? it is a 35mm thick door. Also, will it be ok fitting the latch into the area just below the current handle (see pic)? The intended area is 170mm wide (high), whilst the mortice is 110mm high. Presumably, this is a structural part of the door and cutting it away could weaken it enough to cause the door to fall apart possibly? Or am I worrying too much?
Any thoughts or advice?
Thanks.

 

[Notch7]

I presume you mean a 5 lever sash lock.

They require a 19mm wide mortice, so on a 35mm door you would be left with 8mm either side, it’s not much

And your intended location is right on the mid rail and you would be cutting most of the joint out, I suppose if you use a 2 1/2” sash lock you will need a mortice 65mm deep leaving maybe 20mm to the glazing rebate.

Personally I think you are better fitting 2 deadbolts, at 1/3 and 2/3 of the height and keeping a tubular latch for the middle

 

[RrogerD]

I presume you mean a 5 lever sash lock.

They require a 19mm wide mortice, so on a 35mm door you would be left with 8mm either side, it’s not much

And your intended location is right on the mid rail and you would be cutting most of the joint out, I suppose if you use a 2 1/2” sash lock you will need a mortice 65mm deep leaving maybe 20mm to the glazing rebate.

Personally I think you are better fitting 2 deadbolts, at 1/3 and 2/3 of the height and keeping a tubular latch for the middle

Thanks for the reply.
Hmmm. Some very useful comments, thank you.
The bit where the current handle is, is 80mm wide before the glass. I think your idea of the deadbolts is the best solution.
Would you happen to know if the deadbolts would satisfy insurance requirements? I know that they normally ask for 5-lever locks.

 

[JohnD]

I want to fit a decent security lock to this internal door in the form of a 5-lever night latch.

Can you show an example pic or link of what you have in mind?

Such locks exist but are very rare.

What are the dimensions of the door stile?

A glazed panel can easily be broken, but may be noisy.

Is this door your main entry or exit to the house?

 

[RrogerD]

Can you show an example pic or link of what you have in mind?

Such locks exist but are very rare.

What are the dimensions of the door stile?

A glazed panel can easily be broken, but may be noisy.

Is this door your main entry or exit to the house?

Apologies, I meant a sash lock.
The door stile is 80mm wide.
I'll be putting in 6mm safety glass.
It is to the rear of the house. Into the conservatory and then 'secure' garden. ie with no access apart from climbing over neighbour's fences.

 

[JohnD]

It would be unwise to put a mortice lock in the door where you would cut away the tenon of the rail. You could fit a small 5-lever deadlock at shoulder height, and bolts top and bottom. You already have a latch and handle.

Note the dimensions of the 3G220 which I use in similar positions.

https://www.locksandfittingsdirect.co.uk/wp-content/uploads/sites/2/2023/04/UNION_0137_3-600x600.png

I think the Willenhall M8 lock has been discontinued but they sometimes crop up in old stock or on ebay. I looked for a Legge recently and could not find one.

Do you mean easy-break 6mm toughened glass, or difficult-break laminated glass (about 6.3mm), secured with glazing tape?

You will need to read your home insurance policy, but you might find it requires a BS3621 lock on your main entry door, and any lock, plus mortice bolts with removable keys, on other doors. It will probably also accept multipoint locking on plastic doors.

 

[foxhole]

Insurance usually ask what’s on external doors not internal , they base premiums on what you have, so poor security means higher premiums.

 

[JohnD]

Some conservatories are built to the standards of a garden shed, and may have a roof of plastic sheet. I don't know if the door to them is considered an internal or external door.