Has anyone put a safety gate to prevent a dementia adult from going down stairs?

debdaughter: No, not everyone in New Hampshire is rich.

I probably would not trust a gate that is not attached to the wall. An adults weight might just push a baby gate down. Unless it is there just to serve as a reminder not to use steps, but you could have a rope or ribbon for that. Walmart sells inexpensive door alarms that stick in the door, but the surface of the door and door frame must be pretty even with each other. Walmart also sells an inexpensive motion detector. These items have a chime sound or an alarm.

The safest place for someone who is not safe to be on the stairs would be to put them downstairs or out in one of those granny pods that are newly available. Google granny pods

Have you ever thought of installing a stair lift or even an elevator? When you get him using the handicap lift or elevator, only then can you rest assured your elder won't fall down the steps. Another thing you're going to need to face is the fact that eventually your elder will need a memory care  facility. You're definitely going to need some help on this one at some point and it sounds like you may have to put this elder into memory care if you can't afford to install the lift or elevator because one day as you mentioned, he may actually end up falling down the stairs. One concern I have about the safety gate is it can prove to be a fire hazard if there were ever a fire and he had to escape. How can he get out if you have a safety gate preventing him from going downstairs in the event of an emergency such as a fire or even a medical emergency? You can't if he's home alone  so I personally would scrap the safety gate idea, especially for the sake of it becoming a trap if there were to ever be a fire and he can't get out. If this were to happen and he was home alone and he died in that fire, his blood would be on your hands for installing that safety gate and the Fire Chief would probably flip his lid and you would be in a ton of serious trouble. The alternative would be to just put him down stairs and leave him there and just put the safety gate across the stairway until you get home so he stays downstairs until you get home but only as long as he has a downstairs bathroom and anything else he needs. I would seriously frown on leaving him home alone with dementia in case he does go out wandering around. I personally would either consider having someone sit with him while you're gone or put him into an adult daycare or even best yet, memory care he'll need eventually anyway

There was a door to the basement which we locked much to mothers dismay....putting a gate at the top of a second story was problematic. It has to be tall enough, heavily anchored, lockable or hard to open. We moved her to the main floor and closed off a formal living room to a very nice bedroom and put a decorative outdoor metal gate at the bottom which is hard to open and gets landlocked sometimes. It works for now! Powder room only on main floor. She is accompanied by an aide 3-4× a week to shower upstairs. It's hard but it's working