How to add door latches to a hollow metal door frame?

[dannyrus]

Hey folks,

I've got one of these door latches I'm wanting to install onto our front door - yet another 10-minute job that I've hit a hurdle with.

https://www.bunnings.com.au/syneco-chrome-door-guard_p0223207

The door frame is metal over a brick wall. When I drilled this hole:

 

There was about a 30mm void inside the frame, between it and the brick behind it. I expected to find solid brick so had planned to insert lugs and screw into them, but the void means there's nothing for the lug to hold onto (side view below).

I considered using pop rivets instead, but thought I'd run this past the community here first in case there's a better option. I'm concerned that pop rivets wouldn't offer as much strength as screws etc, especially considering this is supposed to be a security device...!

Any suggestions appreciated, thanks a mill in advance

Cheers, Danny.

[MitchellMc]

Hi @dannyrus,

I suspect pop rivets would offer the same strength as the shortish timber screws included in that kit. I'd recommend going for the 4.8mm diameter if they fit the pre-drilled holes. The mechanism stops a door from being opened; it's not a security device on the same level as a deadbolt that will help prevent the door from being kicked in.

It would be best to use a Ramset 6 x 75mm Countersunk DynaBolt Plus Masonry Anchor in your situation. However, I'd say the head and shank will be far too thick to pass through the pre-drilled holes in the latch. 

You might like to consider a security door chain instead. I believe some of these would allow you to fix into the bricks on the left of the frame instead of the door frame itself.

Let me mention @TedBear to see if he has any nifty ideas.

Please let me know if you have any questions.

Mitchell

[Noyade]

Morning @dannyrus 

"There was about a 30mm void inside the frame"

My thought would be nut rivets - steel, not aluminium. I believe Bunnings sell them, and the application gun. Kincrome?

[Noyade]

Morning again @dannyrus 

"My thought would be nut rivets"

Maybe not such a practical thought Graeme.

Amazingly the sun is shining and tinkering outside with the kit (it is Kincrome), even for an M6 bolt the hole will need to be at least 9mm and looking at your photo above (hard to see) you seem to be very close to the edge of the frame? What size hole did you drill there?

And is it worth the cost if you're unlikely to use the kit again?

Second Saturday thought - as @MitchellMc suggested above - large (4.8mm) pop rivets may be a better and more economical answer.

I'd like to know how you get on with this. 👍

Cheers!

[dannyrus]

Thanks everyone,

@Noyade you're right, it is pretty close to the edge, mainly because of the positions of the screws on the plate.

I did like the idea of nut rivets but as you say, it might be too close. I'll try the pop rivets path and report back here once it's done. Will be a weekend job.

Thank you team! Always so helpful in here much appreciated.

Cheers, Danny.