First, let me rename "the provisions of 5.820, 5.821, and 5.822" to "X, Y, and Z". Now, we have:
X, Y, and Z shall not apply to (a) fences, terraces or walls six (6') feet
or less in height, nor to (b) terraces, steps, unroofed porches or other
similar features not over three (3') feet high
Here's how I parse it:
According to (a), X, Y, and Z do not apply to:
- Fences 6' or less in height
- Terraces 6' or less in height
- Walls 6' or less in height
According to (b), X, Y, and Z do not apply to:
- Terraces 3' or less in height
- Steps, unroofed porches, etc., 3' or less in height
If I'm correct, then X, Y, and Z do apply to:
- Fences and Walls taller than 6 feet [according to (a)]
- Steps, unroofed porches, etc., taller than 3 feet [according to (b)]
However, there's a bit of a gray area for Terraces between 3 and 6 feet tall. Let's assume we have a 5'-tall terrace. The second clause (b) would lead one to think X, Y, and Z would apply, but the first clause (a) seems to negate that.