I have an existing patio adjacent to the back of the house. I really want to expland the patio but I am concerned about covering up the roots for an extablished vine maple (~15' Tall x 15' Wide). The patio extension would be on the south side, which is the downhill side of the tree. I envision the uphill edge of the extension to be about 6" from the base of the rock wall which is about 5' from the trunk. As the picture shows, from the existing patio there is a 3-4" step down to a row of bricks and the grass which then tapers down the hill. Because the grade slopes down away from the tree I don't think that the excavation process will cause issues with the roots. I am more concerced about covering the roots with ~150 square feet of concrete. For what it is worth, I don't water the tree during the summer. I have thought about a low deck instead, but I like the idea of concrete to better match the existing surface and for the low maintenance. Of course the best way to match the old surface, fine grain surface, to the new will be challenging. How concerned should I be? Thanks!