BN wrote:
My contractor notched my joists in the kitchen about an inch from the
top. The floor joists are 9" in height and 1 1/2" inch in width and 15'
in length. It is under the kitchen. The notch cut is about 1" cubed in
volume and at the top. Also the notches are 5' 8" from the start of the
span. Every joist was notched the same way to fit a gas pipe (black pipe).

How bad is this? Is it something to lose sleep over?

THanks


The notch has reduced the effective depth of the
joist by the depth of the notch. So assume the
notch is 1 inch deep the effective depth of the
joist is 9" - 1" = 8"

If that is a 15 foot clear span (no support except
at the ends) it is either unacceptable or close to
unacceptable depending on the joist spacing.
Based on my tables you should have 2 x 10's and
they should be Douglas fir or larch on 16" centers
as a minimum. The plumber should have put the
pipe through holes near the center of the joist.
That would not reduce the strength of the joist
whereas a notch on the top or the bottom does
reduce the strength