Question
Currently in the proccess of building a new house and we have an oak tree approx. 30ft away from the foundation of the foundation that was dug.  It seemed to be doing well (3-4 months from foundation going in) until this last month when every leave turned brown and many have fallen off.  Could this be wilt, shock, etc...  The only sign of life have been many birds up high in the tree making me think bugs?  However on the trunk of the tree and almost all the way to the top on the main (trunk) of the tree there are small buds or offshoots starting however nothing on the major limbs... I am debating cutting it down before we do final grade on the property.  I am in need of help with what to do or what may be causing this issue!!

Answer
What often happens during construction is equipment will run over the root system and compacts the soil near the tree. This can kill some or most of the root system and the tree does not have enough food and water to leaf out fully. There maybe enough roots left to keep the tree alive but can only support a few amount of foliage. We call these epicormic branches--sprout from the main trunk that will make the tree look like a bottle brush. A picture would help but from what you described I am afraid that I would recommend that the tree be removed. You can leave it but you will not get a true tree form and the dead branches will fall etc. It maybe best to go ahead and take it down now before the house and yard are finished. Sorry.