Question
We recently purchased a house that has a bald cypress about 20 feet from the concrete foundation.  The knees are short, about 3 to 4 inches high, but the are starting to come through the flag stone patio.  The tree was planted 5 to 6 years ago and already stands at least 50 ft tall.  We love the tree and the shade it provides.  I would like to dig up a portion that faces the house or runs to the house and put steel barriers in the ground to protect the foundation.  Of the 360 degrees around the tree, I would have to cut back about 30 to 40 degree wide area, so roughly 10 to 15 percent of the root system.  If I take out that much of the root system will it effect the tree very much?  Will the root system find some way around the barriers and continue in the same direction?  Once I cut the roots, if I put "Roundup" on the disconnected side will it kill that part of the root that can not be pulled out of the ground?
Thank you in advance for all of your help.
George

Answer
I am having a hard time picturing this setup. Root barriers will work along foundations, most are made out of hard plastic. They need to be about 24 inches wide along the foundation. These can be placed near the foundation that way not many roots are disturbed. Generally if you do not cut moire than 25 % of the roots the tree will not be effected much. You may get a small bit of dieback on the limbs toward the root cutting. You can treat the roots that are cut off the tree (those away from the tree) with Roundup without harming the tree as long as the roots were severed and the round up can not be transported through the roots to the tree. This may not be needed if you stay close to the foundation.

If you are in the U.S. I would suggest that you call the local office of the State Forestry Agency and ask one of their Foresters to come out and take a look and advise you. This is a free service and their number should be in the phone book. In other countries--they may have a forestry agency but I do not know.

Here is a web link to different types and manufacturers of root barriers.

http://www.4specs.com/s/32/32-9452.html