The inspection I had done on my concrete foundation calls for one root barrier to go between the slab and one live oak tree that is 12 feet from a corner of the home. One of the contractors I called for bids thinks I should have four root barriers. Two of them for other trees on my lot and one to protect the foundation from a neighbor’s tree.
One of the trees is in the front yard, is pretty big, and frankly I’m surprised that Mike The Engineer who did the inspection wasn’t concerned about it. It is a maple, and he doesn’t think the roots of that species of tree are all that invasive. Tom The Contractor thinks they are.
Another point of disagreement is the row of hollies along the west side of the house. They can get huge. I have to trim them back at least twice a year. For reasons I can’t recall but were most likely based on laziness, I let them go for a couple years without a “haircut.” They grew a good twelve feet tall and were peeking over the roof line before I delivered their next whacking. Mike The Engineer said if they were red-tipped phontinias they would have to go, but hollies are ok. Tom The Contractor says both types of shrubs are bad for foundations because they can draw enough moisture from under the slab to contribute to settling.
The biggest point of disagreement between these two professionals is whether or not I need underpinning, or piers, installed. Tom The Contractor, who sells and installs piers, doesn’t think I need them. He thinks by cutting all roots headed under the slab, installing four root barriers, removing the row of hollies next to the house and installing a good quality soaker hose system he can get enough water back into the clay soils under the slab to reverse the settling and get some lift.
Mike The Engineer also thinks the foundation will benefit from a root barrier and soaker hoses and suggests waiting a year after installing those items to see if there won’t be some lift. But his report calls for piers after that. 21 of them. Many U.S. dollars.
So I’ve had two experienced professionals come out and look at the foundation and have two different opinions on what to do, both based on “I’ve been doing this for many moons and I know what’s best.”
I emailed the engineer’s inspection report to another foundation repair contractor for a bid on the root barrier a week ago, but haven’t heard back. I guess they are busy. Stay tuned.