Can Tree Roots Damage Your Home? Everything New Zealand Homeowners Need to Know
- The Firewood Company
- 2 hours ago
- 11 min read
Trees add enormous value to our properties. They provide shade during hot New Zealand summers, create shelter from strong winds, improve privacy, attract native birds and often become one of the most loved features in a garden.
But beneath every healthy tree is an equally impressive root system, one that most homeowners never see.
While tree roots are essential for keeping a tree stable and healthy, they can sometimes create problems when they grow too close to homes, driveways, retaining walls, fences or underground services and even roads (as we witness every day in Malbrough) .
One of the most common questions homeowners ask is:
Can tree roots damage my house?
The answer is yes! But probably not in the way most people imagine.
Despite what many people believe, tree roots don't usually smash their way through solid concrete foundations or pipes. Instead, they take advantage of existing weaknesses, expanding into small cracks, joints or areas where moisture is already present.
Understanding how roots grow, recognising the early warning signs and choosing the right tree for the right location can help prevent expensive repairs in the future.
In this guide, we'll explain how tree roots behave, when they become a genuine concern and what you should do if you think a tree is affecting your property.
How Do Tree Roots Grow?
One of the biggest misconceptions about trees is that their roots grow straight down into the ground. In reality, most tree roots spread outwards rather than downwards.
The majority of a tree's active root system is found within the top 300 to 600 millimetres of soil, where oxygen, nutrients and moisture are most readily available.
In fact, a mature tree's root system can often spread well beyond the edge of its canopy, extending several metres away from the trunk depending on the species, soil type and surrounding environment.
Rather than searching for concrete to break apart, roots naturally grow towards:
Water
Oxygen
Nutrient-rich soil
Loose ground
Spaces where they can expand more easily
This explains why roots are commonly found beneath lawns, garden beds, driveways, drainage lines and retaining walls.
As they increase in size over many years, they can place gradual pressure on nearby structures, particularly if those structures already have small weaknesses or are built within the tree's natural growing zone.
Can Tree Roots Really Damage Foundations?
This is probably the biggest myth surrounding tree roots. Contrary to popular belief, healthy tree roots rarely have the strength to break through well-built concrete foundations.
Instead, problems generally occur because roots exploit existing weaknesses or indirectly affect the soil that supports a building.
The top three reasons this can happen is:
1. Soil Movement
Some soils naturally shrink when they become dry and expand again after rain. Large trees remove significant amounts of moisture from the surrounding soil as part of their normal growth. Over time, this can contribute to ground movement in certain soil types, particularly during long dry periods.
If foundations are already vulnerable, this movement may contribute to cracking or uneven settlement.
2. Existing Cracks
Tiny cracks can develop in foundations over many years due to normal settlement, temperature changes or previous movement. Tree roots don't normally create these cracks, but they may grow into spaces that already exist, gradually widening them as the roots increase in diameter.
3. Older Homes
Many older New Zealand homes were built before modern engineering standards and may have shallower foundations or ageing drainage systems. On these properties, large trees growing close to the home deserve closer attention than those planted further away.
Can Tree Roots Damage Driveways?
Yes, and this is one of the most common issues homeowners experience. Unlike house foundations, driveways and paths are often thinner and more susceptible to movement.
As roots slowly increase in diameter, they can lift paving, asphalt or concrete slabs, creating uneven surfaces over time.
You might notice:
Raised sections of concrete
Cracks appearing in straight lines
Uneven paving
Trip hazards
Sunken sections beside lifted areas
This type of damage usually develops gradually over several years rather than appearing suddenly.
The likelihood of damage depends on several factors, including:
Tree species
Root size
Distance from the driveway
Soil conditions
Driveway construction
Not every nearby tree will cause driveway problems, but large, fast-growing species planted close to hard surfaces deserve regular monitoring.
Can Tree Roots Damage Underground Pipes?
This is another area surrounded by myths, and one of the most searched questions online. Tree roots don't generally crush modern water or sewer pipes. However, they are extremely good at finding moisture.
If an underground pipe has a loose joint, tiny crack or ageing seal, even a small amount of escaping water can attract nearby roots.
Over time, fine roots may enter the opening and continue growing inside the pipe, where there is a reliable source of water and nutrients.
As the roots expand, they can:
Restrict water flow
Catch debris
Cause repeated blockages
Lead to pipe damage
Increase pressure on weakened joints
This is why older clay or concrete drainage systems are often more susceptible to root intrusion than newer PVC pipework. Homeowners who experience recurring blocked drains should consider whether nearby trees may be contributing to the problem before assuming the plumbing itself is at fault.
Can Tree Roots Damage Retaining Walls?
Retaining walls are another structure that can be affected by tree roots, particularly when large trees are planted too close. As roots increase in diameter, they may place pressure on the wall or contribute to soil movement behind it.
Signs that deserve investigation include:
Bulging walls
Leaning retaining walls
Cracks in masonry
Movement between timber sleepers
Gaps appearing around posts
Soil pushing through joins
Retaining walls naturally experience significant pressure from the soil they hold back, so additional force from expanding roots can accelerate deterioration over time.
However, not every leaning retaining wall is caused by trees. Drainage issues, poor construction and normal ageing are also common contributors.
Which Trees Are Most Likely to Cause Problems?
Not every tree has an aggressive root system, and simply having a large tree in your garden doesn't automatically mean your home is at risk. Some species naturally develop wider or more vigorous root systems than others, particularly those that grow quickly or seek out reliable sources of moisture.
Throughout New Zealand, property owners should pay particular attention to mature:
Willow trees
Poplar trees
Eucalyptus (gum trees)
Large pine trees
Macrocarpa
Elm trees
Plane trees
That doesn't mean these trees should automatically be removed. Many provide valuable shelter, privacy and environmental benefits when planted in the right location.
Instead, the key is understanding whether the tree has enough space to mature without conflicting with nearby buildings, underground services or hard landscaping.
"A healthy tree in the right place is an asset," says The Firewood Company owner Tiri Johnsen. "Most of the issues we see come from trees that have simply outgrown the space they were planted in decades earlier."
Seven Warning Signs Tree Roots Could Be Affecting Your Property
Tree root damage rarely happens overnight. In most cases, the warning signs develop gradually over several years, making them easy to overlook until repairs become much more expensive.
Keep an eye out for:
1. Cracks Appearing in Driveways
Hairline cracks aren't unusual as concrete ages. However, if sections begin lifting or the crack widens over time, expanding roots may be contributing to the movement.
2. Repeatedly Blocked Drains
If your drains continue blocking despite being professionally cleared, tree roots may have entered ageing pipework through damaged joints or existing openings.
3. Uneven Paving
Pavers that begin rocking underfoot or lifting at the edges may indicate root growth beneath the surface.
4. Leaning Garden Walls
Movement in small retaining walls, edging or brick garden features can sometimes point to expanding roots placing pressure beneath or behind the structure.
5. Large Surface Roots
Roots appearing above ground aren't always a problem. However, extensive surface roots may interfere with mowing, create trip hazards or indicate the tree has limited space to grow underground.
6. Changes Following Dry Summers
After prolonged dry weather, some homeowners notice new cracks around outdoor concrete or garden structures. While several factors may be involved, moisture loss associated with mature trees can sometimes contribute to soil movement.
7. Trees Growing Too Close to Structures
Even if no damage is visible today, trees planted very close to homes, sheds or retaining walls deserve periodic inspections as they mature. Early advice is usually far less expensive than emergency repairs later.
Can You Cut Tree Roots?
Many homeowners assume cutting a troublesome root is the quickest solution. Unfortunately, it's rarely that simple.
Tree roots perform several important jobs.
They:
Anchor the tree during strong winds
Absorb water and nutrients
Store energy
Support healthy growth
Removing large structural roots without understanding the tree's stability can weaken the entire tree. In some situations, cutting roots may increase the likelihood of a tree becoming unstable during severe weather.
It can also leave the tree vulnerable to disease by creating large wounds beneath the soil surface.
"One of the biggest mistakes people make is cutting roots without thinking about what those roots are actually doing," says Tiri. "Sometimes you solve one problem but create a much bigger safety issue."
If roots are becoming a concern, it's always worth seeking professional advice before reaching for a chainsaw.
Should You Remove the Tree?
Fortunately, removal isn't always necessary. Depending on the situation, several options may help manage the problem while allowing the tree to remain.
These may include:
Careful pruning
Root management
Installing root barriers
Improving drainage
Monitoring the tree's condition
Removing nearby hard landscaping instead
Tree removal generally becomes the preferred option when:
The tree presents a significant safety risk.
Structural damage is continuing to worsen.
The tree is dead or declining.
The tree has clearly outgrown the available space.
Ongoing maintenance is no longer practical.
Every property is different, which is why a professional assessment is often the most cost-effective place to start.
Choosing the Right Tree for the Right Location
Many root-related issues begin long before the tree reaches maturity. When planting a new tree, consider not only how it looks today but how large it could become in 20 or 30 years.
Before planting, think about:
The mature height and spread
Root growth habits
Distance from buildings
Underground pipes
Water mains
Septic systems
Retaining walls
Driveways
Fences
Neighbouring properties
Allowing enough space from the beginning can significantly reduce future maintenance while helping the tree develop into a healthy, long-lived feature.
As a general guide, larger tree species should be planted well away from homes and major structures, while smaller ornamental varieties are often better suited to compact residential gardens.
"The best tree is one that's still in the right place 30 years from now," says Tiri. "A little planning today can save thousands of dollars in maintenance and repairs down the track."
When Should You Ask for Professional Advice?
You don't need to wait until damage becomes obvious. A professional inspection can provide peace of mind if you're concerned about a mature tree growing close to your home or other structures.
It's worth arranging an assessment if:
You're planning renovations near an established tree.
You're seeing signs of movement around your property.
A large tree has suffered storm damage.
You're unsure whether roots are affecting underground services.
You're considering removing or pruning a mature tree.
A tree has changed noticeably in appearance or stability.
Sometimes the advice may simply be to monitor the tree. In other cases, early intervention can prevent far more expensive repairs in the future.
Frequently Asked Questions - Tree Roots
Can tree roots damage house foundations?
Tree roots rarely crack well-built foundations by themselves. More commonly, roots take advantage of existing weaknesses or contribute to changes in the surrounding soil. Older homes, ageing foundations and certain soil types may be more susceptible to movement, making it important to monitor large trees growing close to buildings.
Can tree roots crack concrete?
Yes, tree roots can contribute to cracked concrete, particularly in driveways, paths and patios. As roots gradually increase in diameter, they can place pressure on concrete slabs or exploit small existing cracks, causing sections to lift or separate over time.
Can tree roots damage underground pipes?
Tree roots are naturally attracted to moisture. If underground pipes have damaged joints, small cracks or ageing seals, roots can enter through these openings and continue growing inside the pipe, potentially causing blockages and restricting water flow.
How close should a tree be to a house?
The ideal planting distance depends on the species and its mature size. Larger trees should generally be planted well away from homes, retaining walls, driveways and underground services to allow sufficient room for both the canopy and root system to develop safely.
Which trees have the most aggressive root systems?
Several fast-growing tree species are known for developing extensive root systems, including willow, poplar, eucalyptus (gum trees) and some mature pine species. However, every tree behaves differently depending on soil conditions, available moisture and growing space.
Should exposed tree roots be covered?
In many cases, exposed roots are perfectly natural and should not be buried under large amounts of additional soil. Covering roots too deeply can reduce oxygen availability and negatively affect the health of the tree. If exposed roots are creating a hazard or concern, seek professional advice before making changes.
Can I cut tree roots without harming the tree?
Cutting tree roots should never be done without understanding their importance. Large structural roots help stabilise the tree and transport water and nutrients. Removing significant roots may weaken the tree, increase the risk of failure during storms and leave it vulnerable to disease.
Do tree roots keep growing after a tree is removed?
Once a tree has been removed, the root system will eventually stop growing because it no longer receives energy from the leaves. Depending on the species, existing roots may slowly decay over several years.
Can removing a tree stop foundation damage?
If tree roots are contributing to movement or pressure around a property, removing the tree may help prevent further issues. However, existing structural damage should still be assessed by an appropriately qualified building or engineering professional where necessary.
How do I know if roots are causing my driveway to lift?
Raised sections of concrete, uneven paving, widening cracks and visible roots close to the surface may all indicate that tree roots are contributing to movement. A professional inspection can help determine whether roots are the primary cause or whether other ground conditions are involved.
Can tree roots damage retaining walls?
Yes. As roots expand over time, they can place additional pressure on retaining walls or contribute to soil movement behind them. Bulging walls, cracking and noticeable leaning should all be investigated before the problem becomes more significant.
Are all large trees a risk to my property?
No. Many mature trees remain healthy and stable for decades without causing any issues. Factors such as species, planting location, soil conditions, ongoing maintenance and overall tree health all influence whether a tree is likely to create future problems.
When should I have a tree inspected?
It's a good idea to arrange an inspection if you notice significant changes in the tree's appearance, visible structural damage, lifting around nearby hard surfaces, repeated blocked drains or if the tree has suffered storm damage. Regular inspections can often identify issues before they become expensive repairs.
Can tree roots affect my neighbour's property?
Yes. Tree roots don't recognise property boundaries and may extend well beyond your fence line. In some situations, they can affect neighbouring driveways, gardens, retaining walls or underground services. If you're concerned about a mature tree near a boundary, seeking advice early can help avoid future disputes.
Is removing a tree always the best solution?
Not necessarily. Many trees can continue to thrive safely with the right management, including pruning, monitoring or improving the surrounding environment. Tree removal is generally recommended when the tree presents an unacceptable safety risk, has significantly outgrown its location or is causing ongoing damage that cannot be managed in another way.
Need Advice About a Tree on Your Property?
Trees are one of the greatest investments you can make in your property, but like any living part of your landscape, they benefit from ongoing care and attention. Understanding how tree roots behave, and recognising when something doesn't look quite right, can help you avoid expensive repairs while protecting the long-term health of your trees.
Whether you're concerned about a cracked driveway, a leaning retaining wall or a mature tree growing close to your home, seeking professional advice early can make all the difference.
"Every property is different, and every tree tells its own story," says The Firewood Company owner Tiri Johnsen. "Our job isn't to remove every tree we see, it's to help homeowners make informed decisions that keep their families, homes and properties safe for years to come."
At The Firewood Company, we've worked with homeowners, farmers and lifestyle block owners across Marlborough to assess mature trees, safely remove those that have become hazardous and provide practical advice on managing trees before they become costly problems.
If you're unsure whether a tree on your property is causing damage, or simply want peace of mind, we're happy to inspect it and provide honest, advice.
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