Many times, on consulting visits, I jokingly say to the building committee, "If you don't like your pastor, make him the head of the building committee and you have better than a 65% chance he'll leave before the project is complete."
The senior pastor has an already very demanding job where he operates not only under the scrutiny of God, but often under the scrutiny of demanding and abusive congregants. If your pastoral team is handling the very demanding position of driving the Building Committee throughout the expansion campaign (which can take 3 to 5 years), who is caring for the sheep? CDS says: "You build the body ... we will construct the building". Protect your pastor against burnout -- make sure he has the support from lay leadership and from the body when you commit to moving or expanding your facilities.