cat door inside?
 

new addition to the house requires a litterbox. not ideal with a toddler around.

i want to add a cat door to one of our interior doors. is there a kit for a hollow core door? or do i need a whole new door as well ?

Home Depot sells several different kits that will work.

Any cat door will work with a HC door. There is honeycomb bridging inside to hold the 2 skins together. Leave 2" at the bottom when you mark out the cut. If you have a raised panel molded door, it will be more difficult but it will still work.

Can you put it in the wall next to door? Easier/cheaper to patch sheetrock than replace the door later.