Installing a cat door

[emver]

I've just ordered a Cat Mate flap which is 174mm high internally. But I'm going to fit it through a wall which is 13" thick in total,
so it will be a 13" long tunnel with the flap on the outside only. Clearly there's a difference between stepping though a 174mm high hole
and crawling through a 174mm high tunnel. So now I'm worried that I should have bought the larger size. Our cats are small and medium. The reason I didn't order the large size was that I don't want them bringing in mice or even rats during the night or while we're
away.
Has anybody had experience with a cat tunnel through a modern cavity wall?

 

[catspaw66]

I believe your cats will have no problems once they realize what is on the other end.
If my mental conversion tables are correct, 175mm is 7 inches. My largest cat can go through a 5 inch (125mm) round hole. Of course, like I state, that is my opinion from 30 straight years of having multiple cats.

 

[emver]

Thanks for your reply catspaw66. My point was really that this is a tunnel through a 13" thick wall.
I know that our cats can easily step through a small cat flap in a door or window, but crawling through a tunnel
of the same width and height might be a different matter. So has anybody else built a tunnel through a thick wall,
and if so what height was the tunnel? And is there a flap at each end? I'm planning to have just one flap on the outside.

 

[FeebysOwner]

Hi. I don't know whether or not there should be a flap/door on both ends, but it probably would be a good idea so that you are able to close off both if/when needed. Why allow access to the tunnel when you don't want the cats going out? I do think you need to take a look at what the standard size of cat tunnels that are used for toys to make your decision about your tunnel through the thick wall. I would think the size of your tunnel shouldn't be any smaller than that since the cats will have 13" to travel through.

I found an example of a cat door with extenders, like you would need if you were not making your own, but I couldn't find anything about it's size. Here it is:
SUREFLAP Cat Door Tunnel Extender, Brown - Chewy.com

EDIT: I just now found information about the dimensions:
SureFlap Cat Flap Tunnel Extender, Brown, 2.4" L X 7.9" W X 10.2" H | Petco

 

[MoonstoneWolf]

Is this to the outside of the house? If so I'd be cautious about that. Especially if you have other wildlife in the area. I'd wake up to a raccoon sitting on my bed staring at me lol

 

[emver]

In the end I've bought 3 cat flaps, all from Cat Mate because I thought the quality sounded good.
Having owned a few cat flaps in the past, all of which my cats have found a way to break, I wanted
something robust. And my first impressions of the PetMate products are very favourable. They look
well made and strong.
So I bought a standard size one with wall liner, a large size one, and a round one which can be installed
in a window, a door or a wall. I've almost finished installing the standard one with a fabricated tunnel of
my own design to avoid the high cost of several extenders to make up the length of the tunnel.
Tomorrow I'll start to encourage the cats to use it, which will be fun, and I'll report back. I'll have 2 spare new
catflaps if anybody is interested in buying one.

PS. I've noticed that there are a lot of Chinese catflaps on ebay which use the name Cat Mate or Pet Mate
in the title of the listing, mostly from a seller in Lichfield. I strongly disapprove of Chinese sellers who pretend that
their items are products from reputable manufacturers such as Pet Mate, so I would urge people on here to avoid them.