Can Trees Damage Your House Foundations?
It is a question we get asked more often in a hot, dry summer. Someone notices a crack above a door, or the back door has started sticking, and the big tree at the bottom of the garden suddenly looks suspicious. Sometimes the tree is to blame. Often it is not. Either way, it is worth understanding how it works before doing anything drastic.
How trees can cause subsidence
Tree roots do not usually push foundations out of the way. The problem is water. On shrinkable clay soils, which are found in parts of Staffordshire, the ground swells when it is wet and shrinks when it dries out. A large, thirsty tree can draw a lot of water from the soil in summer, and if its roots reach under a house, the clay can shrink enough for the foundations to move.
Houses with shallow foundations, older properties and extensions are most at risk. Trees like willow, poplar, oak and some conifers are particularly thirsty.
Warning signs
- New cracks inside or out, especially around doors and windows.
- Cracks that are wider at the top than the bottom.
- Doors and windows that start to stick.
- Cracks that open up in summer and close again in winter.
Small hairline cracks are very common, especially in newer houses or after plastering, and are not necessarily anything to worry about.
Do not just fell the tree
This is the big one. If a tree has been growing near a house for many years, removing it suddenly can cause the opposite problem, called heave. The clay takes on water it has not had for years, swells and can push the foundations upwards. That can be just as damaging as subsidence.
If you think you have a subsidence problem, contact your home insurer first. They will usually arrange for a structural engineer or specialist to investigate, which may include monitoring cracks, soil tests and root identification. Taking a tree out before that process can also complicate your claim.
What we can do
Once the cause is clear, the answer might be a regular crown reduction to cut down how much water the tree uses, a phased reduction over several years, or in some cases removal. We work alongside whatever the engineer or insurer recommends.
Roots and drains
Roots also get the blame for blocked drains. In most cases the drain was already cracked or had a loose joint, and roots found the water. Fixing the drain usually solves it without needing to remove the tree.
Questions we get asked
How close is too close for a tree near my house?
It depends on the type of tree, its size and the soil. As a rough guide, a mature tree closer to the house than its own height is worth keeping an eye on, especially on clay.
Is my neighbour responsible if their tree damages my house?
Possibly, but it is a complicated area. Speak to your insurer, who can deal with it on your behalf.
Do I need permission to reduce a tree near my house?
Only if it is protected. See our post on whether you need permission to cut down a tree in Staffordshire.
Need advice about a tree near your home?
M Bissell Trees and Hedges can look at the tree, give you practical advice and carry out the work once you know what is needed. Call Matt on 07968 421 434 or 01785 82 44 10, or contact us online.