What Causes Uneven Floors in Sydney Homes and How to Fix Them

May 26, 2025

What Causes Uneven Floors in Sydney Homes and How to Fix Them


Ever walked across your lounge room and felt like you were slightly uphill? Or noticed your furniture doesn’t sit quite right, even after a bit of adjusting? You’re probably dealing with uneven floors, and while they might seem like just an odd quirk, they can be a sign of deeper structural issues under your home.


Here’s what causes them, what they could mean for your house, and how you can sort them out for good.


Why Are My Floors Uneven?

Sydney homes cop a lot – shifting soil, sudden storms, ageing materials, and the occasional dodgy extension job. All of these can mess with the stability of your floors over time. Here are some of the usual suspects:


1. Foundation Movement

Sydney’s soil types vary heaps depending on where you live — coastal sand, clay, or rock. Some of these expand and contract when wet or dry, which causes the ground (and your home’s foundation) to move or sink. That movement shows up as sloping or dipping floors.


2. Water Damage or Drainage Issues

Leaky pipes, blocked gutters, or poor stormwater drainage can cause water to pool under your home. When that happens, the soil washes away or softens, leading to sinking foundations or piers. Left unchecked, this can cause serious structural issues.


3. Old Timber Stumps or Supports

If your home was built before the ‘80s, it might be resting on timber stumps. Over time, those can rot, shift, or get eaten by termites — especially in Sydney’s humid conditions. As they break down, your floor goes with them.


4. Uneven Add-Ons or Renovations

It’s not uncommon for extensions or renovations to be built on different footing systems or slab levels. If they weren’t properly levelled from the start, or if one side of the house settles differently over time, the join between old and new can become very noticeable underfoot.


So, How Do You Fix Uneven Floors?

Good question. The right fix depends on the cause, but it’s never a one-size-fits-all job. Here’s how house levelling experts in Sydney (like us) tackle it:


Structural Levelling or Reblocking

If your home sits on stumps or piers, we can lift and level the house by replacing or adjusting them. This process, called reblocking or restumping, helps reset the structure back to where it should be.


Underpinning Foundations

If your concrete slab or footing is sinking, we might recommend underpinning — a method where we install new supports under the existing foundation to stabilise and strengthen it.


Floor Levelling for Surface Fixes

If the problem’s mostly cosmetic, like a slightly uneven slab or high spots, we can use floor levelling compounds to create a smooth surface, especially before laying new flooring.


Don’t Ignore Uneven Floors

It might start with a bit of creaking or a wobble underfoot, but uneven floors can quickly turn into bigger and more expensive problems. Cracked walls, sticking doors, sagging floors — all of it can be traced back to foundation issues if left too long.


Need Help from a
Sydney House Levelling Pro?


Whether you’re just starting to notice a dip or it’s already got you worried, we can help. At Sydney House Leveling, we’ve worked on homes all over the city — from older weatherboards to newer builds — and know exactly how to get things sorted.


  • Free inspections
  • Honest advice (no fluff)
  • Long-term, guaranteed fixes


Let’s get your floors level and your house back on solid
ground. Contact us today!


House being jacked up for foundation repair; dirt ground, red jacks, concrete pillar.
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Underpinning Explained: When Is It Necessary in Sydney? If you’ve noticed cracks in your walls, doors that don’t close properly, or uneven floors, your home’s foundation could be trying to tell you something. In Sydney, where many homes sit on reactive clay soils or older footings, foundation issues aren’t uncommon—and underpinning might be the solution you need. But what exactly is underpinning, and how do you know if it’s necessary for your property? Let’s break it down. What Is Underpinning? Underpinning is the process of strengthening and stabilising the foundation of an existing structure. It involves extending the foundation depth or spreading the load to more stable soil. This ensures that your home remains level, safe, and structurally sound for years to come. For Sydney homes, underpinning is commonly used in house leveling projects to correct subsidence (sinking or movement in the foundation). When Is Underpinning Necessary? Not every crack in your wall means you need underpinning, but here are key signs that suggest it might be time to call in the experts: 1. Significant Foundation Movement If your house has shifted or sunk noticeably, especially in areas with clay-rich or unstable soil, underpinning is often the best long-term solution. 2. Large or Widening Cracks Hairline cracks are normal, but wide cracks (5mm or more) in walls, ceilings, or brickwork indicate serious foundation movement. 3. Uneven or Sloping Floors If your floors slope or feel bouncy, your foundation may no longer be stable. 4. Doors and Windows Sticking When the foundation moves, door and window frames can warp, making them hard to open or close. 5. After Renovations or Extensions If you’re adding a second story or extending your home, underpinning may be required to ensure the foundation can handle the extra weight. Why Underpinning Is Common in Sydney Sydney’s mix of reactive clay soils, older homes, and variable weather conditions makes foundation movement a common issue. Droughts, heavy rainfall, and tree roots can all cause the soil to expand or contract, leading to subsidence. If your home is more than 30 years old or built on sloping ground, regular foundation inspections are a smart precaution. What Happens During Underpinning? The process typically involves: Assessment & Soil Testing – Engineers inspect the site and test soil conditions. Excavation – Sections under the foundation are carefully dug out. Concrete or Resin Injection – New footing material is added to strengthen and level the foundation. Monitoring – The foundation is checked for movement to ensure long-term stability. The exact method depends on your home’s construction and the severity of the issue. Do You Need Underpinning or Just House Leveling? Not all foundation problems require full underpinning. Sometimes, house leveling alone —lifting and adjusting the existing stumps or piers—can fix the problem at a lower cost. A professional assessment will determine whether house leveling or underpinning (or a combination of both) is the right approach. Talk to a Sydney House Leveling Expert If you’ve spotted any of the warning signs, don’t wait—foundation problems only get worse (and more expensive) over time. A professional house leveling and underpinning expert can inspect your property, explain your options, and recommend the best solution. Need help with your Sydney home’s foundation? Get in touch with our experienced team today for an inspection and personalised advice.
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Concrete vs. Steel Underpinning: What’s Best for Sydney Homes? When foundation issues strike, underpinning is often the best solution to stabilise and level your home. But which method should you choose— concrete underpinning or steel underpinning ? Both are effective, but the right choice depends on your home’s construction, soil type, and how severe the foundation movement is. Here’s a breakdown to help Sydney homeowners make an informed decision. Concrete Underpinning: The Traditional Choice What It Is Concrete underpinning involves digging under your existing foundation and pouring concrete to create a deeper, stronger footing. Pros Proven and Reliable – A traditional method with decades of successful use. Cost-Effective – Generally cheaper than steel underpinning for standard residential jobs. Great for Large Areas – Ideal for homes with widespread foundation movement. Cons Slower Installation – Excavation and curing take time, so the process can take weeks. Messy and Disruptive – Requires significant digging around your home. Not Ideal for All Soils – Less effective in very loose or sandy soils. Steel Underpinning: The Modern Alternative What It Is Steel underpinning uses screw piles or driven steel piers installed deep into stable soil or bedrock, then attached to the foundation to lift and support the home. Pros Faster Installation – Can be completed in days, not weeks. Minimal Excavation – Less disruptive to gardens and landscaping. Ideal for Problematic Soils – Works well in Sydney’s reactive clay and sloping blocks. Immediate Load-Bearing – No waiting for concrete to cure. Cons Higher Cost – Steel is generally more expensive upfront. Not Always Necessary – Overkill for minor subsidence issues. Which Is Best for Sydney Homes? Both methods work, but here’s a quick guide: Choose Concrete Underpinning if… ✔ Your home has widespread subsidence or needs a large foundation area reinforced. ✔ You’re on a tighter budget and don’t mind a longer project timeline. Choose Steel Underpinning if… ✔ You’re on reactive clay soil (common in Western Sydney). ✔ Your home is on a sloping block or needs deep stabilisation. ✔ You want a fast, less disruptive solution . In many cases, engineers may recommend a combination of both methods, depending on your property’s unique conditions. Need Expert Advice? Choosing the wrong underpinning method can cost you more in the long run. If you’re noticing cracks, uneven floors, or doors sticking , it’s time to have your foundation professionally assessed. Talk to Sydney’s House Leveling Experts We’ll inspect your home, explain your options, and recommend whether concrete or steel underpinning is best for you. 📞 Call us today to book an inspection and get a tailored solution for your Sydney home.
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