Best way to cut a hole in brick for a cat flap!

Soldato
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6 Jan 2006
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Newcastle upon Tyne
I think the wall is double skin brick so wondering what the best way to cut a hole in it for the cat flap. I’ve got an SDS drill, multi tool and grinder but not sure what will be the easiest to use?

I’ve watched a few YouTube videos but some of them don’t look great so thought I would ask if anyone has any advice on here.

Thanks.
 
Associate
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It's arguably easier to install a cat flap in to a glass door than it is in a brick wall. Albeit maybe not a DIY job.

It also means in the future if you don't have cats or want to sell and restore it to normal you can just replace the glass rather than an irreparable hole in the wall.
 
Soldato
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It's arguably easier to install a cat flap in to a glass door than it is in a brick wall. Albeit maybe not a DIY job.

It also means in the future if you don't have cats or want to sell and restore it to normal you can just replace the glass rather than an irreparable hole in the wall.
This, very much this
 
Soldato
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+1 for looking at an alternative to cutting through the wall. Making the hole is straightforward, but then you'll be left with a hole, a cavity and then another hole. You'll need to put some sort of liner in there, while making sure there's no bridge for damp to get into the inner wall.

It's a whole load of permanent work, I'd get the flap fitted into a door.
 
Man of Honour
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Wiltshire
A core drill bit in whichever size you need, assuming your drill is suitable for using one. Just take it very slowly, its not like drilling a 'normal' hole.
 
Associate
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17 Nov 2015
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Northants
It's arguably easier to install a cat flap in to a glass door than it is in a brick wall. Albeit maybe not a DIY job.

It also means in the future if you don't have cats or want to sell and restore it to normal you can just replace the glass rather than an irreparable hole in the wall.

This! We have a cat flap in the single leaf of our bifolds, which is effectively our back door. Just replace the sealed unit if we want it gone in future.
 
Permabanned
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The outside skin is easy. You just remove all the relevant bricks then cut them to size and pop them back in with mortar, leaving the hole you want. The inner skin is a little more difficult in that usually the best way is drill a pattern of holes then use a chisel on them. Of course you need a hole big enough to frame it internally with wood ( so it's like a tunnel ). You need the hole to be BIG because the cat can not squeeze through a long tunnel easily. If they lose grip with their back legs they are stuck forever, lol. Personally I make it as tall as the cat and all the way to the floor so like a mini doorway and it's easiest to make it one brick and one inch wide.
 
Associate
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31 Oct 2005
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444
I installed a cat flap through a double skin extension wall a few years back. I used a long SDS drill bit initially, then switched to SDS Chisel function.

I fitted this cat flap on the outside and inside: https://www.petsathome.com/shop/en/...magnetic-4-way-locking-classic-cat-flap-white
To cross the cavity I used these: https://www.petsathome.com/shop/en/pets/petsafe-tunnel-extension-for-microchip-cat-flap

You will probably want to get some sand/cement or plaster to patch up around the cat flap and glue the tunnel extensions together before fitting.

Hope that helps.
 
Soldato
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4 Apr 2003
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The tunnel element for a cat through the wall can be very problematic unless you get the very oversized cat flaps and tunnel.

It's a long way to get through if the cats are fairly large.

It's also a very big job to ensure it is installed correctly and the cavity bridge won't cause damp. You have to oversize the holes by some margin then use mortar to fit externally and re-plaster internally.

Thermally you need an inner door too really.

If cat flaps were cylindrical you can simply bore through with a diamond cutter bore at size. Most are not.

As it is you can bore through with something like this 152mm core bit then knock out to fit. It's a slow job and you don't want to use the hammer or fast speed.

Decent sizled cat flaps tend to need c180-200mm holes.

https://www.screwfix.com/p/erbauer-diamond-core-drill-bit-152mm/68843

A good 200mm core bit is c100£ upwards.
 
Soldato
Joined
9 Mar 2003
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14,058
All you need is a core bit of the relevant size, an sds drill and you’ll be through the wall with a clean cut in a few minutes. You can hire the bits if you don’t have one.

The cat flaps designed for walls have 2 doors and an inner liner. You just need to make sure you cat isn’t too big to get though it. My in laws had two of these at different houses and they were fine. The cats took a few days to work it out but otherwise they just used it like a normal cat would. Didn’t seem to bad to install.

You can get it put in the glass door but you’ll not be cutting the glass, rather you’ll be replacing the entire double glazed unit with a flap built in and they are not cheap to have one with a flap built in from the factory.
 
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