QuestionI will be putting up a garden and storage shed (18X20) and the location puts it only about two feet from a red oak tree (10-12 years old). Since I will be pouring a slab with footings I am concerned about losing the tree and the possible cracking of the slab do to root growth. I do not want either to happen. If I build up the foundation a little will this alay the problem?
AnswerA tree can usually survive with 30% of the root system damaged or cut. The way to determine this is draw a circle around the tree where the branch extend to. Then make a line where the trench and root cutting will be and if this cuts more than 39 % of the root system (the pie shape) than you can expect major die back of the foliage from the root cutting. All this will depend on the size of the tree and its crown. The roots are in the first 2 feet or so of the soil so any trenching this deep will sever the roots. The slab itself may not cause much problem but the footing will. If you can pour the slab on top of the ground without significantly disturbing the soil around the tree the tree should be ok. Two feet from a tree is really too close--as the tree grows the limbs will rub the shed and over time even the trunk may rub it. The best thing is to move away from the tree as far as possible.
