A Triad of Pies

Make the 41 integers between -20 and 20 (-20, -19, …, 0, 1, …20) using only the four basic arithmetical operations, square root, the floor function, and, Surprise Surprise, exactly 3 π’s. No more and no less. No other digits or symbols are allowed. You can use as many square roots and floor functions as you like. Parenthesis are allowed. Unary minus sign is not allowed. Exponentiation is not allowed. Anything not explicitly allowed is disallowed.

The floor function for x, written $lfloor x rfloor$, is equal to the greatest integer smaller or equal to x. For example, $lfloor pi rfloor = 3$, $lfloor pi times pi rfloor = 9$
and $lfloor -pi rfloor = −4$.

Shorter is better (i.e. try to find expressions with the minimal number of +, -, $times$, $div$, $lfloorrfloor$ and $sqrt{}$‘s.)

Note: 20 and -11 to -20 are very challenging. (0 to 10 are fun)