Foundation depth is important
The shallow foundations of more mature buildings subside frequently in drought years because the less deep soils dry faster and the tree roots have better access. In the United States and particularly in the Midwest, full cellars or basements are common and it takes prolonged drought to dry these deeper subsoil’s sufficiently for the soil to shrink and cause major damage.
It is not easy for roots to grow into the base of a basement foundation and survive the seasonally wet conditions. Aggressive rooting species (i.e., willow, honeylocust, silver maple, and elm) are more likely to cause gradual sinking than slow growing upland species (i.e., oak and sugar maple).
This gradual sinking is more likely to occur with less deep foundations, very severe droughts, and increased tree water requirements. City arborists are receiving calls to remove trees frequently blamed for the damage. Foundation damage can occur from soil beneath the surface shrinkage during drought in the total absence of roots.
CONFIRM THE INVOLVEMENT OF TREE ROOTS FIRST
Prior to any tree being cut down, the presence of tree roots at the base of the foundation should be confirmed. Lots of trees have been cut down unnecessarily just because they were in close proximity. Roots normally grow horizontally and not very deep beneath the surface. Sometimes when roots encounter the looser backfill dirt near the foundation, they can quickly start growing down. You may be able to locate these roots, by digging a foot or two deep within a several feet of the foundation. If you find a suspect root, cut it off. Unfortunately, in some cases excavation down to the foundation may be necessary. This may have to be done in any case, to repair and stabilize it. Cutting the roots should prevent potential problems, especially if a root barrier is installed to prevent re-growth.Share