Why The soil should slope away from your house: A building inspectors tip for Sydney homes

Intro: Proper drainage around the house is a critical factor that building inspectors look for when assessing properties in Sydney. Having the ground around your home sloping down and away from the foundations is hugely important to prevent moisture damage. Read on to understand why a yard sloping towards the house can cause endless headaches, and how to ensure your Sydney property has suitable drainage.

Section 1 – How Improper Drainage Causes Water Damage

When the ground and lawn around your Sydney house is flat or slopes back towards the exterior walls, it can cause significant water damage over time. Here’s how:

  • Rainfall flows back toward the foundation – Instead of dispersing away, water pools near the footings and concrete slab during wet weather. This provides a constant source of moisture.
  • Raises dampness along walls – Poor drainage results in excessive dampness along external walls where they touch the ground. This dampness seeps inside.
  • Leaks water into basements – For houses with basements or low ground floors, a yard sloping inward directs rain runoff into basement areas leading to flooding.
  • Destroys foundations – Constant dampness rots wooden stump foundations and erodes concrete footings through rising damp. This destabilises the entire house structure.
  • Promotes mould growth – Wet walls create ideal conditions for mould to grow inside your home, posing a health hazard.
  • Ruins flooring – Rising moisture warps and lifts timber flooring, tiles and laminate from the underlying damp slab.

A comprehensive building inspection report will highlight any improper drainage or yard slope issues around the Sydney property.

Section 2 – How Proper Drainage Protects Your Home

Having a sloped yard that redirects water away from your home’s foundations makes a huge difference. Here are the benefits of proper drainage:

  • Keeps foundations dry – With surface runoff directed away from footings, the soil near your foundations stays optimally dry. This preserves the structural integrity.
  • Prevents damp walls – No moisture buildup occurs along external walls, keeping the inner surfaces bone dry.
  • Avoids flooding – For properties with basements or low ground floor levels, drainage away from the house prevents flooding inside these spaces.
  • Minimises mould – When moisture along walls is eliminated, conditions for mould development are removed. This creates a healthier living environment.
  • Protects floors – Floors no longer lift or warp thanks to drier slabs and reduced rising damp under the home.
  • Maintains value – Good drainage is attractive to buyers and adds value at resale as it reduces maintenance costs and prevents water damage.

During building inspections in Sydney, properly sloped gardens that don’t direct water back toward the house are a positive sign.

Section 3 – How Much Slope is Recommended?

Building code in Australia recommends a minimum slope of 50mm fall over the first metre away from the house. The more slope the better.

This means, for every 1 metre stretch near the house walls, the ground should drop 5cm lower than the house slab level. The recommended slope ratios are:

  • 1:100 – For every 100mm horizontally away from the wall, a 10mm vertical fall.
  • 1:50 – For every 50mm away, a 10mm fall.
  • 1:20 – 1 vertical unit down for every 20 horizontal units. This is the optimal amount of slope.

These slope ratios quickly drain water away from the perimeter while being gentle enough to mow and landscape. Aim for at least 100mm fall in the first metre.

Section 4 – Inspecting Drainage During Sydney Building Inspections

When getting a professional pre-purchase building inspection in Sydney, make sure the inspector checks and comments on drainage. Here are key things they should assess:

  • Overall slope direction – Use a level to verify the yard slopes away from house on all sides. Drainage toward any part of the foundation is a concern.
  • Slope ratios – Inspector should check gradient falls versus distances. 1:50 or better is ideal.
  • Surface water ponding – Any dips or hollows near the house where water collects signals a problem.
  • Gutter overflow direction – Eaves gutters should redirect runoff away from the house, not toward it.
  • Downpipe discharge – Downpipes from gutters should not release water close to the home’s concrete slab edge.
  • Retaining walls – Any retaining structures should be far enough from the house with suitable drainage.
  • Paved areas – Solid paved surfaces near the home should similarly slope away.

A report from the Sydney building inspector detailing any drainage faults allows you to request remediation from the seller or seek a price reduction to cover future drainage works.

Section 5 – How to Improve Drainage Around Your Home

If the property you purchase in Sydney is found to have inadequate drainage or yard slope, there are solutions to improve the situation:

  • Add garden beds and mounds angling down from house.
  • Re-grade the soil to achieve a better fall.
  • Install agricultural drains near the perimeter.
  • Shift any downpipes discharging too close.
  • Use retaining walls, terracing or sleeper steps to change levels.
  • Replace paved surfaces near house with permeable options like gravel.
  • Extend eaves gutters and redirect away from the slab.

The most affordable remedy is redistributing garden soil to create a sloped flower bed or shrubbery zone around the home. Improving drainage protects your investment and avoids endless damp problems.


Having your home’s yard and garden sloping away from the foundations is a golden rule the building inspectors look for when checking Sydney properties pre-purchase. Drainage sloping back toward the house causes chronic damp issues and water damage. Ensure any property you buy has adequate slope by getting a professional building inspection report. If inadequacies are found, simple landscaping remedies can redirect runoff away to keep your home’s structural integrity intact for years to come.