I just had my roof replaced but I want to check the contractor did the job
correctly.

I'm concern about

the minimum width of roofing shakes (cedar)
the minimum distance between the edge of one shake and the edge of the one
below/above it
the minimum thickness

Is there a national guideline for this type of thing, or where should I go
look for a rules that applies to my house (in seattle)? The State? The City?
The manufacturer of the shake?