Many people find this unpalatable, as there are often legitimate reasons for the delays. Instead, consider penalties for every two-weeks or every month the project runs over. Others suggest that you create deadlines for events such as parties, weddings and family reunions. This will often spur a builder who is juggling multiple jobs to get yours done. And to make sure you get what you expected, have a contract.
People are so busy.
Remember, adding on to the home is a bit like cosmetic surgery. Even though you elect to do it, it doesn't discount the fact that there's bound to be some discomfort. If you expect a little bruising, you won't be disappointed. Oh, and one more thing. Maybe you should ask the kids how they are holding up.