I'm looking to create an SLA that would only be active for after business hours and weekend/holidays.

In our environment, we have a contract that states a 30 minutes response/2 hour resolution for after hours and on weekends.  I would like to create something that would notify our IT Manager if the response time elapses.

During regular business hours, our IT Manager does not wish to be notified if the 30 minute response elapses.

Any ideas?