Mr. Pham came to us with a familiar problem. He was struggling to figure out why these small hairline cracks keep popping up in the middle of his house. Nothing too worrisome as far as severity goes, more of an annoyance. He would get them fixed only for them to come back the next season.
He had already had the perimeter of his foundation repaired and all measurements pointed to no failure every time he saw the cracks reappear.
Once we determined that the problem was not severe enough to install invasive piers in the middle of the house, we pointed out that the neighbors' trees on both side of his house were close enough to have roots reaching to the middle in the areas he was seeing movement.
The decision was made to install root barriers down the sides in between both sets of trees. You can see from the pictures below the amount of roots we pulled out of the trench we dug for both ones.
For this particular design we went with 30 inch deep trenches using 30 mil thick HDPE barrier. Each trench is hand dug to avoid any utilities or sprinkler systems. Both barriers took 1 day to install.
Edit (10/15/2019): We are pleased to announce that 6 months after they were installed, Mr. Pham hasn't seen any new hairline cracks appear!