Tree Roots & House Foundations: Poplars, Clay & Moisture Depletion

Reader notes poplars transpire 150 L/day, drying expansive clay, causing foundation subsidence. What trees are poplars? NC relevance?

Poplar Species

True poplars (Populus): cottonwoods, aspens, balsam poplar—willow family, wet-site trees. Yellow-poplar (Liriodendron) is unrelated (magnolia family).

Subsidence Reality

• Only on shrink-swell clays.
• Trees accelerate drying but soil type is primary driver.
• Large trees too close to house = branch rub before root damage.

NC Context

Red clay (stable) often used under foundations. Black belt clay (AL/MS) cracks in drought. Tree roots not the main cause if foundation properly built.

Plant large trees ≥20 ft from house; maintain foundation drainage.