On 29/01/2011 20:00, Bob Eager wrote:
On Sat, 29 Jan 2011 19:20:52 +0000, Lobster wrote:

On 29/01/2011 16:28, Roger Mills wrote:
On 29/01/2011 09:08, rope wrote:

As others have said, a bi-fold door can be opened, simply by pushing or
pulling in the middle - so a magnet on its own won't prevent it being
opened, even if it stops it from opening by itself.

It seems to me that what you need is the sort of lock which is fitted
to sliding patio doors - which either has a hook or expands sideways to
prevent the door from being slid open. Such a lock should prevent a
bi-fold door from being opened.

I tangled with one of these things myself recently; fitted to the
bathroom of a buy-to-let I'd bought. Door opened outwards, but the
problem was that you couldn't actually close the bifold without someone
pushing the door from the outside.

Never mind, I thought; just needs a pull-knob attaching to the middle of
the door. I fitted that, and it worked fine until I tried to open the
door - the presence of the knob in the middle of the bifold gap
effectively prevented the door from opening wide enough to allow me out!
Duh.

So, on to plan B... what was needed was a flush-fitting draw-pull
arrangement. I sourced one of those and attacked the door to make a
recess for it, where upon I discovered the door was a completely hollow
egg-box affair, so nowhere to screw it to. In the end I glued the
draw-pull in place with NoNails and so far it's apparently holding, but
I'm not holding my breath. Like I said... bloody horrible things!

I wanted to fix one of these (between kitchen and utility room) so the
cats couldn't push it open. I had the same problem with a projection in
the 'fold', but it wasn't too bad if I used one of these, which has been
on there years now...

http://www.atlanticshed.com/ring_latch.htm

My God - what's with the Robo-girl?!!

FWIW my one is like this:
http://www.mascotmetal.com/pcat-gifs/products-large1/20610-b.jpg

I suspect both will suffer similarly from egg-box door syndrome though

David