Home construction and remodeling can be particularly hazardous to trees.
It is important to protect any trees in the area before beginning a construction project. Most important is to thoroughly prune them several months in advance of the work, and to protect the trunk and roots from damage by construction equipment. Tree roots are very shallow, so even shallow trenching can seriously injure or kill a tree. In Riverwoods, with its heavy clay, tree roots are typically only 8 inches to 10 inches deep.

Trees react strongly to injury, but the reaction is slow to appear. Tree injury is generally not apparent for three to five years after the injury. By the time trees show injury, significant decline in health has occurred. In addition, tree roots extend well beyond the branch tips ­ up to two or three times the overall branch spread of a tree. That means that even minor construction activity well beyond the extent of the tree’s branches can injure tree roots.

Soil compaction sufficient to kill a tree can occur through a one-time event, such as moving a heavy vehicle across tree roots, or a series of seemingly insignificant events, such as periodic disturbance of the soil layer around a tree.

For more information about protecting your trees during construction visit these websites:
The University of Minnesota Extension Service
http://www.extension.umn.edu/distribution/housingandclothing/DK6135.html
The International Society of Agriculture
http://www.treesaregood.com/treecare/avoiding_construction.aspx