Subsidence and Landscaping: How Your Garden Choices Impact Your Home’s Stability

When it comes to maintaining your home, most homeowners focus on keeping the inside of the property in top condition.

However, what surrounds your home is equally important—especially your landscaping choices. The plants, trees, and overall design of your garden can significantly impact your home’s foundation stability and either reduce or increase the risk of subsidence.

In this post, we’ll dive into the connection between subsidence and landscaping, and explore how thoughtful gardening choices can help protect your home.

Understanding Subsidence and How It Affects Your Home

Subsidence is the downward movement of the ground that causes a property’s foundation to become unstable.

When the soil underneath your home moves, either by shrinking or losing strength, it can create cracks in the walls, misaligned doors and windows, and uneven floors. Unlike natural settling, subsidence is an ongoing issue that can worsen if not addressed.

Factors like soil type, water presence, and surrounding vegetation can all contribute to subsidence. Your landscaping choices—particularly the types of plants and trees you have and where they’re positioned—are a major influence on soil behaviour.

Why Landscaping Can Cause or Prevent Subsidence

Landscaping plays a critical role in how soil behaves around your home. Here are some key reasons why:

• Water Demand from Trees and Shrubs: Large trees and plants have extensive root systems that need significant water. When planted near foundations, these plants absorb moisture from the soil, causing it to shrink, especially in clay soils. During dry spells, this effect is even more pronounced, creating a risk for subsidence.
• Soil Erosion from Poor Drainage: Landscaping can either improve or worsen drainage around your home. Poor drainage can lead to water pooling around foundations, saturating the soil and causing it to lose strength. This weakens the foundation, making it more prone to subsidence.
• Soil Composition and Plant Choice: Different plants affect soil differently. Some plants, such as trees with deep, water-seeking roots, are more likely to disrupt the soil near your foundation. Clay soils are particularly susceptible to shifting based on moisture levels and root activity, meaning that plants can either stabilise or disrupt them based on the water they draw.

Choosing the Right Trees and Plants to Prevent Subsidence

Choosing the right plants for your garden is one of the most effective ways to minimise the risk of subsidence.

Here are some general guidelines:

Select Trees with Low Water Demand

When it comes to trees, avoid species with extensive, deep root systems that seek water from great depths. Trees with high water demands include:

• Willow
• Oak
• Poplar
• Eucalyptus

Instead, opt for trees that are less water-dependent and have shallower root systems, such as:

• Silver birch
• Rowan
• Holly

These trees are less likely to destabilise the ground beneath your foundation.

Plant Trees at a Safe Distance

Even if you select trees with low water demand, it’s essential to plant them at a safe distance from your home. As a rule of thumb, plant trees at a distance equal to their mature height.

For example, if a tree will grow to be 20 feet tall, plant it at least 20 feet away from your home. This distance reduces the likelihood that the roots will interfere with soil stability around your foundation.

Use Shrubs and Smaller Plants Close to the House

Small shrubs and plants with minimal root depth are far less likely to cause subsidence. These types of plants draw much less water from the soil and have root systems that aren’t likely to reach or disrupt your home’s foundation.

Consider using these types of plants for beds and borders around the house.

Consider Drought-Tolerant Plants

Drought-tolerant plants generally have lower water needs, which helps maintain consistent soil moisture levels.

These plants are a great choice for landscaping around foundations, as they reduce the need for excessive watering and are less likely to cause soil contraction or saturation.

Some drought-tolerant plants include:

• Lavender
• Sage
• Succulents (in appropriate climates)
• Ornamental grasses

Managing Tree Roots to Reduce Subsidence Risks

If you already have large trees around your home, removing them may not always be the best or most practical solution.

In fact, removing a tree abruptly can sometimes cause “heave”—where the soil expands and swells in the absence of water demand, potentially causing further structural issues.

Instead, consider these alternatives:

• Regular Pruning: Regularly pruning trees can limit their water uptake by reducing the size of the tree, particularly the branches and leaves. This can slow the growth of the roots and limit their reach, reducing the risk to your foundation. Consult an arborist to determine the most effective pruning routine for your trees.
• Root Barriers: Installing root barriers can prevent tree roots from encroaching on your foundation. These barriers are typically made of plastic or metal and are buried between the tree and your home to redirect roots downward or in another direction. Root barriers can be a useful preventative measure for newly planted trees or young trees that are close to the home.
• Tree Maintenance by an Arborist: Hiring an arborist to monitor and maintain trees near your home is a proactive way to manage root systems and prevent subsidence. Arborists can recommend specific treatments, such as root pruning or selective watering, to ensure that trees around your home are managed in a way that protects your foundation.

Proper Drainage Solutions to Prevent Soil Saturation

Drainage is one of the most important factors in subsidence prevention, as it influences soil moisture levels and stability.

Here’s how to create effective drainage around your property:

• Gutter Maintenance: Clean and functional gutters are essential to directing water away from your foundation. Regularly clean gutters and downspouts to prevent clogs that lead to water pooling near your home. Ensure that downspouts extend at least a few feet from your foundation to prevent soil saturation.
• Permeable Landscaping Solutions: Using permeable materials for walkways, patios, and driveways allows water to seep into the ground gradually rather than pooling around your foundation. Gravel, permeable concrete, and other water-absorbent materials help manage water flow and prevent excess saturation around your home’s base.
• Install French Drains: French drains are trenches filled with gravel or rock that help redirect water away from your foundation. These drains are particularly useful in areas with heavy rainfall or properties prone to standing water. Properly placed French drains can make a significant difference in preventing water buildup and subsidence.
• Landscape Sloping: Ensure that the ground around your home slopes away from the foundation. This allows water to naturally flow away from the property, preventing soil from becoming waterlogged. A slight slope (around 5%) is usually sufficient to achieve proper drainage.

Soil Type Considerations for Preventing Subsidence

Different soil types react to moisture changes differently, and knowing your soil type can help you make better landscaping decisions.

• Clay Soil: Clay soil expands when wet and shrinks when dry, making it highly susceptible to subsidence. If your property has clay soil, avoid water-demanding trees, ensure consistent soil moisture, and be particularly cautious with large trees near the foundation.
• Sandy Soil: Sandy soil has excellent drainage, meaning water doesn’t tend to pool. However, it also doesn’t hold moisture well, which can cause stability issues in dry climates. Adding organic matter to sandy soil can help it retain moisture more evenly.
• Loamy Soil: Loamy soil strikes a good balance between moisture retention and drainage. Homes with loamy soil generally have lower subsidence risks, but it’s still wise to monitor moisture levels and be cautious with tree placement.

Warning Signs of Subsidence to Watch For

Even with careful landscaping and drainage management, it’s essential to stay vigilant for any signs of subsidence. Common signs include:

• Diagonal Cracks in Walls: Cracks that appear diagonally, especially around doors and windows, could be a sign of subsidence.
• Doors and Windows Sticking: If doors and windows suddenly become difficult to open or close, it may indicate that your home’s foundation has shifted.
• Uneven Floors: Sloping or uneven floors can be a sign of foundation movement.
• Gaps Between Walls and Frames: Gaps around window and door frames may appear if the foundation is shifting.

Taking Action if You Suspect Subsidence

If you notice any signs of subsidence, it’s essential to act quickly. Contact a structural engineer or surveyor to assess the issue and determine the best course of action.

In some cases, foundation underpinning or soil stabilization may be necessary to prevent further movement.

Final Thoughts: Building a Subsidence-Resistant Landscape

While landscaping can beautify your home and increase property value, it can also play a significant role in preventing subsidence.

Thoughtful tree selection, strategic plant placement, proper drainage, and routine maintenance are all key components of a subsidence-resistant landscape.

By following these tips, you can protect your home’s stability, maintain its value, and enjoy a beautiful, well-managed garden that enhances your property rather than putting it at risk.