Blocking off a 15-20cm gap between to garage brick walls

Angle bracket and a composite plank to cover the gap?

Cover the drain pipe with something like this, but a home-brewed somewhat cheaper version 🙂

It'll fill the gap too https://www.insight-security.com/galvanised-anti-climb-downpipe-covers

Cheers for the replies

Found two blocks of wood which were the right length which another neigbour was throwing out and when put side by side almost filled the gap

Ive screwed them to each other, put them in the gap and then using a scrap peice of wood i made up 3 wedges, hammered them in between the wooden block and my garage wall and the blocks are now rock solid so hopefully that will stop any cats and foxes trying to get down there

Cats will just climb straight up the front and drop down behind it.

Little shits that they are.

Expanding foam for the win.

Is the drain pipe attached properly. It shouldn't be falling off so easily.

And have you blocked the 'front' of the gap? If something gets in from above can it still get out?

Cats will just climb straight up the front and drop down behind it.

Little shits that they are.

Is the drain pipe attached properly. It shouldn't be falling off so easily.

And have you blocked the 'front' of the gap? If something gets in from above can it still get out?

The is no way to attach the horizontal section of the drain pipe, it sits on top of the boundry wall which runs between the garages, there is no space to get in there to attach it to anything, the down pipes are attached at each end and are secured to the boundry and garage wall

Its blocked at the front of the garages to stop the foxes and cats trying to get down there, the space between the rear of the two gargaes is left open (although slightly overgrown with bushes) so if they somehow manage to get/fall down there they do have a way of getting back out

The amount of cats we have around here is getting ridiculous, next door have 6 cats at my last count (they had 3 but then had kittens which they kept 3 of) then another neigbour next to them has two cats, plus other neighbours further down from them have cats too and a neighbour in the other direction has 2 also, with them and the foxes it can be quite noisy with fights and them running across everyones consevatory roofs as they chase each other

A guy 4-5 doors down has an aviery so i bet he loves having all these cats around!

I know you've already done it, but I'd try and find an offcut of mesh or security fence so that you maintain airflow down the gap and don't end up with damp garages.  You could attached it 30cm back from the face of the garages so its practically unnoticeable.

They cant climb up the front

Unless it's sanded smooth and/or painted, the cat will just run up it. Mine used to run up the wall of the shed so he could glare at people/animals and offensive leaves from a position of safety on the roof.

I know 1 maybe 2 cats should be max but an aviary these things should be banned, all those wild birds cooped up together like in an open prison where disease could easily be a big problem 

Why do folk want wild animals for pets?

they would need to try and leap over 7ft to get near the top of it 

next door’s cat leaps on to the top of a six foot fence with ease, and very little run up.

If you attach a small bit of chicken wire or similar at the top overhanging in the direction they come from, they won't be able to jump up, as they normally need to 'run up' a fence and this will stop them getting onto the top.

If cats keep getting stuck in the gap, it sounds like the problem will solve itself, and eventually the gap will end up filled in.

Couldn't you just put a large dog in the gap to deter them?