dundonald wrote:
Ian Stirling thoughtfully wrote:

dundonald wrote:
I'm laying flooring [1] in my loft. The wiring is simply thrown over the
joists rather than a hole drilled centrally through the joist and the wiring
passed through the hole. Is it good practice to cut a little nick out of
the joist, enough to lay the wiring for the flooring to flush with the joist
over the top? Is this detrimental to the structure?

Yes.
Cutting out a 10% section of beam at the top reduces strength by at best
20%.
What about routing a groove in the chipboard?

Not quite sure how that would work.

Where you would cut a nick into the joist, instead cut a nick out of the
chipboard with a router.