You have my sympathy. Was in a similar situation and tried lots of things... hiding myself in a conference room, headphones, being artificially mean, blocking out parts of my calendar as alone time, telling people I preferred to be left alone for the next few hours - unfortunately none of it worked because when people want something from you their impulse is to turn around and ask you when the barrier is so low. I'll admit that it wasn't a one way street, I probably unknowingly did it to people when they were in the zone.

The only thing that really solves it is if you can convince your employer to let you work remotely even a day or 2 - thats when I actually got to do real work. Just my 2 cents.

In my experience, the open office idea only works well if you've planned your company around it. I worked at one place where we were all open, but by convention, everything short of a true "the site is down" emergency started with asynchronous communication. IM and group chat, mostly. If it took more than a few messages, it might move to verbal, but it always started in a form I could ignore for a while if I felt like it.

Unfortunately, that only works if it's part of the company culture and each new employee sees it pretty clearly.

No whiteboards? What kind of startup doesn't have loads of whiteboards? You should go buy a load of that paint you can use to turn walls into whiteboards and paint your desk and cupboards and floor - www.ideapaint.com

No, we have whiteboards. They're just across the room on the outer walls where I can't reach them easily. We also went cheap and bought melamine bathroom panels that are impossible to erase.

Thanks for the tip!