Question
Hello,

We recently bought a new home. The driveway has never been paved and we were planning to do so until we noticed all the tree roots. From what I have been reading, it seems not to be a good idea to pave over or remove the roots. Do you have another suggestion? We love the trees and do not want to harm them.
Thanks.

Julie

Answer
It will depend a great deal on how long the drive has been there. Is this a new home to you are is it built within the last three years? The effects of the drive will not usually show up in foliage damage for about three years after the construction. The fill and the weight of the cars will compact the soil causing the air spaces in the soil to decrease and this results in root damage which will show up as foliage dieback. If the drive has been there for years the tree has compensated by now for the roots that are under the drive and is relying on the rest of the root system for its food and water. It also will depend on how close the trees are to the drive, the species of the trees  and the percent of roots that the drive could damage. If you cut more than 30% of a hardwoods roots you will see more damage than if the tree were a conifer. Thirty percent loss of roots is about all that a tree can stand without seriously damaging the tree.
If it is an older drive paving over the roots that are there would cause the tree to lose the water from that area but would not add to the compaction. There are porous materials for drives that will allow moisture to get to the roots below.
There are really too many unknowns for me to give a direct answer. I would suggest you contact a local Certified Arborist/ Landscaper only and ask them what to do. Here is a web link to the organization that certifies Arborist.
http://www.isa-arbor.com/findArborist/findarborist.aspx