Tree roots and buildings: what surveyors, a council and extension services say

This page reports what the official source says. It is not legal advice: ask the office named here. It does not say whether any root has damaged any building. Stafford Borough Council names a building surveyor, an arboricultural consultant or a structural engineer for that question, and RICS says an RICS member can work out whether there is subsidence and its likely cause. Stafford Borough Council says to report suspected tree-related subsidence to the building insurer immediately.

Clay soil and subsidence

The Royal Institution of Chartered Surveyors (RICS) consumer guide Subsidence defines subsidence as foundations moving downward because the strata supporting a building change, and says it is different from settlement. It says some houses stand on shrinkable soil such as clay, where moisture drops in a long dry spell or water is drawn out of the soil by trees and bushes, and as the clay shrinks the foundations drop. It says water leaking into the soil from a broken drain or main, and past mining, are other causes.

The guide says the first signs are usually visible cracks in one area of the house, which may need to be measured and monitored for as long as 12 months, and that doors or windows sticking, torn wallpaper and sloping solid floors may also show movement. It says an RICS member can work out whether there is subsidence and what the likely cause is, and that removing a tree can in very occasional cases add to the problem. It says an RICS member can advise, or put an owner in touch with someone who can, on whether a tree should be removed or pruned to reduce the moisture it takes out of the soil.

Stafford Borough Council's page Damage to property alleged to be caused by trees says that when tree roots enter shrinkable clay soil they can take up enough moisture to make it dry and shrink, so a foundation built on it may move. It says most areas of that borough are not clay. It tells owners who suspect tree-related subsidence to report it immediately to the building insurer, which will probably investigate and produce evidence that either blames a tree or identifies other causes. It lists the information the council normally requires for tree work applications on protected trees, including foundation type and depth, soil type to a depth of approximately 3m, evidence of roots below foundation level and monitoring details. It says soil heave can only occur where subsidence has occurred before, so a tree that did not cause clay shrinkage cannot cause heave by being removed.

Who pays, as RICS describes it

The RICS guide says to check whether a building insurance policy covers the cost of investigation and repair, and says an insurer's own experts are often appointed at the insurer's own cost, which needs to be established upfront. It says a policy excess will probably be specified in the insurance documents. The guide does not say what any particular policy covers.

Drains and pipes

The Stafford page says roots follow drains to exploit condensation on the outside of pipes and may dislodge joints, but that it is more usual for roots to enter an already damaged drain. It says that where a drain is blocked by roots, repairing the drain will usually be the solution rather than felling the tree. Purdue University Extension's answer on roots and foundations, posted October 27, 2020, says roots are opportunistic and grow where it is easiest. It says that roots which meet a hard, sealed surface, for example a pipe, curb or foundation, are typically redirected sideways or up and over, but that if there is a breach or crack nearby they can exploit it in search of moisture. It says sewer pipes are not damaged by roots but are found by roots when they leak.

Foundations and paving

A University of Georgia Cooperative Extension article, Don't Invite Tree Roots into Your Home, dated April 15, 1998, says that for most well-designed and installed foundations, sidewalks and driveways roots cannot breach the space, and that poor designs can encourage roots. It says trees are often the scapegoats for faulty design, engineering and maintenance, and that gaps, pores and unprotected coarse sand beneath pavement are open invitations. The guide on trees and construction covers what the standards say about building near trees.

The sources side by side

Source	Country	Points to
RICS	United Kingdom	An RICS surveyor and the building insurer
Stafford Borough Council	England	The building insurer, a consultant arborist or building surveyor
Purdue Extension	United States	Whether a breach or crack gives roots a way in
University of Georgia	United States	Design and construction of the hard surface

Who to call

Your building insurer: the council page tells owners who suspect tree-related subsidence to report it to the insurer first
RICS Find a Surveyor: the RICS guide points to its member directory for surveyors who can work out the cause
Consulting arborists by country: the credentials and registers consulting arborists hold in each country
Tree protection offices: the offices that handle permits for work on protected trees