What is the minumin distance from the line to a wall.

Fed rules say 6' minimum and "preferably" at least 10'.

USVA rules say 2 meters is "recommended" and 3 meters on the sidelines, 4 meters on the end lines is required for all nationally sanctioned matches.

Of course, we play in gyms all the time with less than 6ft/2m clearance and we just have to make allowances by granting a replay if the lack of minimum clearance interfers with a player's play on the ball.

-Homer-