How to control heat-loss through this catio door?

A couple years ago, I helped my daughter build a catio onto the front of the house. See: https://permies.com/t/221400/Cattio#1881456

During the cold months, our choice is to close the door or hemorrhage heat to the outside. See the door, below. We have a standard house door with a special storm door that has a pet flap in it. Things are fine with the interior door closed, but the cats like to go out down to about ~15F/-10C. So we've been talking about something to go between the two doors to limit the heat lost through the storm door but continue to allow feline egress.

My first thought is to put a shower-stall curtain rod either at the top or midway up the doorway (to allow light) and fabricate a plain quilt of some kind with one or more vertical slits at the bottom that the cats can learn to traverse. My wife is thinking about something more extensive with fabric top and bottom and a double-layer clear-plastic window at window height, with a door or slits at the bottom and various options that might help block off the openings. We've played with adapting those heatlocks used in the doorway of walk-in freezers with overlapping strips of heavy vinyl or whatever.

We're not really sure which way to take things and I wonder if anyone else has dealt with something like this or just has clever ideas that we haven't thought about.

Some of these may be mutually exclusive, but:

- We want it to remain there for the winter and then be easy to pack away.
- We want to be able to close the interior door and leave it in place overnight.
- We want it to be easy to move temporarily if we have to go out into the catio.
- I would prefer that it not be plastic.
- We would prefer it not block the window as a light source.
- It would be nice if it looked good, and it has to not look terrible.
- We can leave the interior door open wide or only opened like eight inches if that matters to the solution.

Have you considered putting a pet door into the main door?

Having lived in MN, i suggest building an entry way onto the outside of your home to serve as an airlock/mud room.  Of course, the added pet door Carla suggested could be incorporated into it.

Carla Burke wrote:Have you considered putting a pet door into the main door?

We have, but the doors are so close that we think they'd interfere with each other. If they were a foot apart, that might well be the best solution.

John F Dean wrote:Having lived in MN, i suggest building an entry way onto the outside of your home to serve as an airlock/mud room.  Of course, the added pet door Carla suggested could be incorporated into it.

Immediately to the right of that door on the outside wall is a window leading into our bedroom. It's a terrible placement just in general, but it would be especially bad if we built a shed/vestibule thing. We're considering that on the main exterior door we use that leads into the kitchen, but I don't think it's in the cards for this door.

ahhh... 24/7/365 cat doors lol!

yours is a tricky situation... i see logs..

if you you not in LOVE with the main door i would suggest you cut a open hole in that door that is larger... tall enough that the cat door can freely open inwards. you can frame it out nicely and make a panel insert out of the cutout to re-insert if need be..

you are always gonna have drafts/gaps - but this would go a long way to reducing the inflow and basically provide you with that second barrier you seek... already in place..

hope this helps - cheers!

James, are you suggesting just an opening and not some kind of flap?

yes - exactly... 2 flaps will not work so you are stuck with a single flap to the outside regardless.

as you are limited to the doors, you cannot add a tunnel to mitigate the drafts (a tunnel would give you the 2 flap option)

you will have a second barrier of sorts this way, a lot of cold air will be trapped in between - i see a significant overhang wall so hopefully wind is not going to be too bad.

it's a thought - not perfect but it would help - that glass door is pretty thin on it's own.

cheers!

I was thinking something like this (though this one ain't cheap), where it's covered, but instead of swinging, they go up into it, to get out:
https://www.chewy.com/petsafe-electronic-pet-door/dp/52031

Carla Burke wrote:I was thinking something like this (though this one ain't cheap), where it's covered, but instead of swinging, they go up into it, to get out:
https://www.chewy.com/petsafe-electronic-pet-door/dp/52031

there would still be some collision coming back in and the cats need to have the chip on the collar..

so if the collar gets damaged and/or the door malfunctions and the cat is outside in the winter... they will be stuck there... i took the felt off a couple of cat doors because it was freezing in place during a temperature drop - i could hear the poor cat banging away at it..

not to offend - cheers!

I haven't noticed their flap freezing shut, but the storm-door freezes up. It's because we leave the interior door open so interior humidity freezes out on the door's metal parts as frost and I have to give it a whack to break things up if I have to go out to do something.

it appears you have the flexible type with the magnet at the bottom - shouldn't be a problem - i had the rigid ones with felt edges which swelled up with moisture.

for sure the humidity will be going straight to the outside door - a hole inside will help - you can even get away with a strip door in the inside for an extra barrier - se epic.

cheers!

I was only suggesting the design, not the electronics. If the inside flap is designed more like an awning (so the cat just climbs up & through to open it and get out), and the bottom edge of the flap/awning extends below the hole, much less warmth will escape/cold can get in, and it won't interfere with the storm door. The (hinged) 'awning' would only need to stick out from the door by a couple inches, so the cat could get its nose under, to open it.

Carla Burke wrote:I was only suggesting the design, not the electronics. If the inside flap is designed more like an awning (so the cat just climbs up & through to open it and get out), and the bottom edge of the flap/awning extends below the hole, much less warmth will escape/cold can get in, and it won't interfere with the storm door. The (hinged) 'awning' would only need to stick out from the door by a couple inches, so the cat could get its nose under, to open it.

gotcha - my bad - cheers!

James MacKenzie wrote:

Carla Burke wrote:I was only suggesting the design, not the electronics. If the inside flap is designed more like an awning (so the cat just climbs up & through to open it and get out), and the bottom edge of the flap/awning extends below the hole, much less warmth will escape/cold can get in, and it won't interfere with the storm door. The (hinged) 'awning' would only need to stick out from the door by a couple inches, so the cat could get its nose under, to open it.

gotcha - my bad - cheers!

No worries - I should have been more clear - and alert to exactly what that door was. I saw the picture was very close to what I had in mind, and didn't even notice the electronics, lol. I just thought it was insanely high-priced, for a simple pet door. 🤣

Christopher Weeks wrote:So we've been talking about something to go between the two doors to limit the heat lost through the storm door but continue to allow feline egress.

...

Some of these may be mutually exclusive, but:

- We want it to remain there for the winter and then be easy to pack away.
- We want to be able to close the interior door and leave it in place overnight.
- We want it to be easy to move temporarily if we have to go out into the catio.
- I would prefer that it not be plastic.
- We would prefer it not block the window as a light source.
- It would be nice if it looked good, and it has to not look terrible.
- We can leave the interior door open wide or only opened like eight inches if that matters to the solution.

How about a layer (or two) of Reflectix radiant heat insulation to fit snug about the door frame.

Cut and roll or fold away a fun shape of your choice (e.g. a star, a Christmas tree, or a cat outline) to add a little light in when you need it, and then of course cut a flap around the pet door.

Affix to the door using 3M command strips (or black hook & loop Velcro) for removability at end of season.  

For aesthetics, stitch (or glue) some wool or cotton cloth around the Reflectix in your color of choice (e.g. a nice winter plaid).