For some reason I was assuming he had already got that far although upon another look I see I probably mis-read.
That'd certainly be the approach. I was thinking to the next step because the post title got my mind moving on that track before I had consumed all the details of the post, how to reproduce something like a Contains() function for a duration of days.
I'll be interested to see your full solution, with a proper structure - more elegant I'm sure than the hacky way I'd probably have done it. I was thinking just create the holiday date table with a record for each date to exclude, look up each of them into fields in the table we're doing the calculation in, and don't put them on any forms. I end up with a lot of field creep sometimes...
