Question

why is a 2 x 6 on edge considered a poor handrail?
o a 2 x 6 may not be strong enough to support a persons weight
o it can be difficult to grab
o when wet, a 2 x 6 can become slippery
o 2 x 6 boards tend to shrink as the wood dries, leaving exposed slivers
o there isnt room to get ones hand behind the 2 x 6

Explanation:

A 2 x 6 on edge lacks the structural integrity to support a person's weight well. Its narrow surface can be hard to grip and when wet, it becomes slippery. Also, as the wood dries, it shrinks and can expose splinters.

Answer:

All of the above reasons (a 2 x 6 may not be strong enough to support a person's weight, it can be difficult to grab, when wet, a 2 x 6 can become slippery, 2 x 6 boards tend to shrink as the wood dries, leaving exposed slivers) contribute to why a 2 x 6 on edge is considered a poor handrail.