Do you use the stairs to enter and leave your unit? In other words, would something need to be hinged on one side, say on the dark areas above the bottom steps, with a hook and eye on the other side so you could open and close it as you enter and leave? How high do you think the barricade for your kitten needs to be?

Yes, those stairs are my entrance, so a hinged door would be perfect! I’d like it as high as the ceiling, because she’s gotten past everything else I’ve put there.

You say your landlord is OK with you installing a proper door, and you need something that goes from floor to ceiling and has a hinge on one side. That's a door. Not sure what the dilemma is, unless you think it is too expensive. https://www.homedepot.com/p/Spectrum-36-in-x-80-in-Via-Vinyl-Fruitwood-Accordion-Door-HVS3280F/100084016?MERCH=REC--Pip_Alternatives_Non_HDhome--100066294--100084016--N

I like the sliding doors, but the other problem is my cat likes to get under things. She’ll find the hole in even the most expensive solution and get through it. So, I need something that secures at the floor, ceiling and sides. This is headed in the right direction!

On second thought I don't think a door there is to code.

Hmm...so a temporary solution may work best. Perhaps a taller baby gate that swings?

There’s a bannister and small door at the top of the stairs. We even tried putting netting on the bannister so the cat wouldn’t get through, but she quickly outsmarted it.

Basically the cat isn’t allowed upstairs, but she can have my full 1200 sq ft in the basement and would be happy with it - she just loves exploring!

Not planning to stay here past the end of summer, therefore I really just want a nice temporary solution.

I love the barn door, but the other poster mentioned it might not be up to code...

the sliding barn door wouldn't be an issue, but you'd need something on one end to attach the sliding hardware.

as for an actual fixed door on the stairway, that's something different. for that the landlord would have to check in to what's allowed through your city.

if all you want is temp, then just get a piece of plywood to slide in and out of place

I’ve never used one before, but there are temporary “zip walls” used for construction. I just don’t know how secure the bottom will be, but maybe you can securely attach it to the base of the steps...lots of Command Strips!

Forgot to attach pic

ah the old zip wall! I lived w/this for 9 months while the master bath was being completely redone. the cats managed to sip under it! you really need to tape it down.

That looks like a wide staircase so I don't think a standard door will be wide enough unless you build a wider frame on each side so that a standard door will fit. Since this is your entrance, you'll definitely want something hinged so you're not lifting and moving a barrier. Also, you won't need anything that goes to the ceiling.....a standard door is tall enough to deter a cat as long as it has a flat surface. Remember, you can't use any door that has horizonal bars/mullions since a cat will use them like a ladder, and gates rarely work with cats since they can either jump over them or wedge themselves thru the bars.

One of my cats is an escape artist so I know what you're dealing with.

Plywood would be the cheapest, but you'd still need someone to build a basic jamb and door stop so the door has a tight closure. If you don't, your cat will find the smallest gap and work at it until she wedges the door open.

Shop around to find an affordable door and have a handyman install it. Maybe there won't be an issue with code as long as it doesn't lock??

Just remember if the landlord wants it removed when you leave you'll have to repair where the frame was installed. A good handymand should be able to install it with as few screws as possible.

PS.....Make sure she has toys, cat tower, and maybe leave a radio/tv on if you're gone a lot during the day.

Here's an idea for a barn door gate:

https://www.remodelaholic.com/diy-barn-door-baby-for-stairs/

Did you ever come up with a solution for this? I’m in a similar situation and looking for a temporary solution to keep my cat and dog separate.