Question
We are looking to put a privacy tree between our house and our neighbors house.  We have 12 feet between houses.  We live in North Carolina.  Our neighbor's house sits about three feet above our house on a slight slope.  He is worried about the root system and possible damage to our properties.  Which tree would you recommend and why?

Answer
Neither--both have a width that is too wide for this 12 foot space--the root system will spread about 1 1/2 the width of the foliage. You might look at Cupressus sempervirens. here is a web link to information on this tree. It has a width of 3-5 feet.

http://hort.ufl.edu/trees/CUPSEMA.pdf

I would also recommend that you contact your local office of the North Carolina Forest Service (state agency) and the NC Extension office and ask them about a tree for this space that will grow locally. The main problem is the 12 foot will limit most trees.