On Wed, 27 May 2015 11:26:57 -0700, Bob wrote:

An electrician drilled a one-inch diameter hole in my house's rim joist
while adding a new circuit. A half inch hole is sufficient to pull the
romex through but a larger hole is more convenient for him to insert a
conduit fitting into the sheet rock at the end of the hole.

Would this one inch hole significantly weaken the rim joist? Should I
fill it with epoxy or something?

No to the first question. To the second, caulk would be a good idea to
keep out weather or little critters

What would you say if he drilled a 4-1/4" hole for a dryer vent?