Everyone has their own issues, I guess.
I no longer work from home, but I did for 4 years, supporting HPUX servers for a government contract.
I set up an office in the dining room, which we never used. It had no door, but was a separate space. I could have easily installed a door, but didn't need to.
I sat the family down when the job was offered and asked them if they could respect my workspace if I worked from home. 8yo said yes, but wanted to know how to tell if I was just playing or working. Good question, so I hung a sign by the door. Green on one side and red on the other. Took some getting in the habit to turn it, but it worked well.
3mo gurgled happily and drooled. I took this as agreeing to my terms.
The wife said yes. What she meant was "yes, unless it is an emergency." And by emergency, she meant anything that wandered across her mind at any given point.
So after the first week, we sat down again. I thanked the 8yo for his efforts in watching the sign and respecting work time. Then I asked him if he can help mommy learn how to do this.
The temperature in the room dropped noticeably, but my point was taken. She quit bothering me. In fact, for about 3 days, I thought she had lost her voice, but she got over it.
The youngest, once toddling, was more of an issue, but a baby fence and some teaching solved that after a month or so. At the end of the year I spent a couple weeks vacation time building an office, bathroom, guest room, and home theater in the unfinished basement I had ignored for years. I wound up working in the dining room often, it was easier to interact with the family during downtime.