kevin wrote:

The fact that he wrote 6/12, instead of 1/2 is a hint: 6/12 in roofing
terms is not the same as 1/2 slope = 0.5 slope = 45 degree slant = 100%
grade. It is short for 6 in 12, like, 6 inches drop per foot. Steep,
but not crazy. 4/12 is your classic american suburban house. 12/12 is a
45 degree slant. Your "1/5 pitch" would I guess mean 2.4 in 12, which
is nothing much, since 2 in 12 is considered a flat roof in these
parts, requiring membranes or tar and such, rather than shingles.

- Kevin


I find slope, pitch, and grade a little confusing. In math, slope is
rise over run, which is the same as roofing pitch and ground grade.

If a 0.5 slope is 45 degrees, I suppose slope means a fraction of 90
degrees from horizontal. I haven't come across that before.

Years ago a tree turned out to be significantly taller than I'd
estimated. When I cut it down, it hit a fence. That was embarrassing.

To measure tree heights, I made a clinometer from a short board, a small
piece of plywood, a piece of graph paper, and a weighted cord. You
raise the board to sight the slope, wait for the weight to stop
swinging, pinch the cord against the the plywood, and read the rise and
run on the graph paper.

That has shown me why one section of my roof is less treacherous to walk
on than the rest. The pitches look the same, but the latter is 6/12
while the former is 5/12.

Across the street, my neighbor has 10/12. He weighs 350. While
reshingling, he went up to work with no rope or jacks. He caught the
chimney as he hurtled toward the eave.