How close is too close for a big tree?

There is no single distance. It depends on species, mature size, soil shrinkability and the depth of the foundations, which is why an assessment beats a rule of thumb. Clay soils and shallow foundations are the combination that matters.

Will felling the tree fix the cracks?

Sometimes it makes them worse. On clay, removing a mature tree lets the soil rehydrate and swell, and that heave can lift a foundation further than the shrinkage dropped it. The tree comes out only when the whole picture supports it.

Can roots really block a drain?

Yes, but typically by exploiting a crack or an open joint that was already there. A camera survey shows whether the roots caused the defect or found it, and that decides whether the answer is drainage repair or tree work.

Should I tell my insurer?

If you think the movement is subsidence, yes. Insurers normally appoint the investigation and coordinate any tree work with the structural findings, and going ahead independently can affect the claim.

Caution

Updated 30 August 2026

Tree Roots Near The House

A large tree stands close to the house, and you are worried about the foundations, the drains or the cracks that have appeared.

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What's happening?

Roots very rarely break their way into sound foundations. What actually causes tree-related damage in the UK is water. On shrinkable clay, a large tree draws moisture out of the soil in summer, the clay shrinks, and the ground under a shallow foundation moves — which is subsidence. In a wet winter the clay recovers and swells, and if a tree has been removed the recovery can be greater than the original settlement, which is heave. That is why felling is not automatically the answer and can be the wrong one. Roots do exploit drains, but usually a drain that was already cracked or had open joints. Soil type, distance, species and the age of the foundations all matter more than root size.

What usually causes it?

A large tree on shrinkable clay drawing moisture from beneath a shallow foundation in dry summers
Shallow Victorian or early foundations that were never designed for the moisture demand nearby
A tree that was small when planted and has grown far closer, in influence terms, than it looks
Roots entering a drain through an existing crack or an open joint, then blocking it
Roots lifting a path, drive or wall where the surface was laid straight over the root area
Extraction changing after building work, paving or a new lawn altered how much water reaches the soil
Removing a mature tree from clay soil and triggering heave as the ground rehydrates

Is it dangerous?

Not a physical hazard, but potentially expensive, and the wrong action makes it worse. New cracks that are tapering, diagonal, wider at the top and moving seasonally deserve a proper look, especially around doors and windows and on the side facing the tree. Repeated drain blockages in the same place are worth investigating. What you should not do is fell a mature tree on clay as a precaution: heave following removal has caused more damage to some properties than the tree ever did, and the decision needs a structural and arboricultural view together.

Can I fix it myself?

Gather evidence rather than acting. Photograph and date each crack with a ruler or coin in shot, and repeat monthly — seasonal opening and closing tells a very different story from a crack that only grows. Note the tree's species, height and distance from the wall, and find out whether your soil is clay. Have the drains checked with a camera if blockages keep recurring in the same run. Tell your insurer if you think there is subsidence, because that is their process and they usually appoint the investigation. Do not cut major roots to see if it helps: severing roots on one side can destabilise the tree, which turns a slow problem into a dangerous one.

When should you call a tree surgeon?

Call a tree surgeon for an arboricultural assessment when a large tree is close to the house and you want the risk understood, or alongside a structural engineer once cracking has appeared. If subsidence is suspected, tell the insurer first — investigation and any tree work usually follow their appointed process, and unilateral felling can prejudice a claim. Call sooner if the tree is also showing decay or a lean, because that is a safety question and it does not wait for the clay.

What will the tree surgeon actually do?

Identify the species, measure the height and distance, and assess the moisture demand relative to the soil
Inspect for root activity, drain interference and surface lifting, and advise where a camera survey is needed
Advise on managed crown reduction, cyclical pruning or root barriers as alternatives to felling
Work alongside the structural engineer and insurer where subsidence is being investigated, rather than acting alone
Explain the heave risk before any removal on clay, so the decision is made with that in front of everyone
Carry out the agreed work — reduction, root barrier installation, or removal with replanting advice

Frequently asked questions

We’re happy to answer all your questions.

Sources & References

Stump Left After FellingLow risk Tree Leaning With Lifted RootsHigh risk Neighbour's Branches Overhanging My GardenLow risk

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