Would you like to resize/add-on to your existing structure during your
rehab project?
To have enough space for 10-12 people you'll want up to 288 total square feet.
However, that will be just enough space. If you want ample room to be able to move about comfortably, you'll want at least 392 total square feet. This is a good size deck for entertaining for most people.
Keep in mind that a family of four, that is comfortable dining around a 5-foot-long table will need twice that much space to push back chairs about three feet and safely walk around the dining set.