Expert: Jim Hyland - 7/26/2010

Question
We have a 30' Pine near a concrete patio and some of the roots from the Pine are at the surface.  Can these roots go under and break the concrete (4" thick)?  If so, can these roots be safely pruned?  Thanks.

Answer
A trees roots expend out about 1 1/2 times the branch width. The further from the tree the small the roots are. A patio near a pine can be damaged by the roots. One away from the pine near the outer reaches of the branches would be ok. You can cut up to 25% of the root system with out seriously damaging the tree. Make circle around the tree where the branches extend to and then draw where the roots will be cut and if the cut area exceeds 25 % I would not do it.  You can dig a trench along the patio and install a root barrier to keep roots from growing under the cement. Here is a web link to root barriers. http://www.4specs.com/s/32/32-9452.html