Construction problems are to be expected in many cases. Reputable and experienced contractors will plan for these issues. It is imperative that anyone who is going to have a project done finds out what kinds of delays, if any, the contractor has planned for. Even if this isn't discussed in the contract, you can ask about it when you are discussing the project's specifications and terms.
When there is an unexpected delay that occurs, you have to think about the reason for it. Was it something the contractor could have prevented or planned for? If the answer is "yes," than you might need to read your contract to determine what recourse you have. As we recently discussed, this might be going through arbitration, but it might also entail filing a lawsuit in court.