Living in a classic Sydney apartment has its charm, but buildings from the 1960s to 1980s often hide a costly secret beneath the floorboards: magnesite. What was once a cheap flooring solution is now a known cause of "concrete cancer," a structural nightmare that can cost NSW homeowners and strata bodies hundreds of thousands, if not millions, in repairs. But is it actually dangerous? We spoke with building remediation experts at @ElymentGroup to uncover the truth about the risks to your health and your property. What Exactly is Magnesite Flooring? Magnesite is a cement-like compound (magnesium oxychloride) that was widely used as a floor-levelling and soundproofing layer in Sydney and across NSW. It was popular in multi-storey apartment blocks built between the 1960s and late 1980s. It was poured as a slurry over the concrete slab before the final floor coverings (like tiles, carpet, or vinyl) were installed. Its appeal was simple: it was cheap, fast, and effective at smoothing uneven slabs. The "Dangerous" Question: Health vs. Structural Risks When homeowners hear "dangerous," they often think of health. So, let's clear that up first. Health Risks: Is Magnesite Flooring Toxic? "In its stable, covered state, magnesite flooring is generally not considered a direct health hazard," explains an expert from Elyment Group. "It's not like asbestos, which releases harmful fibres just by being present." The primary health risk is minimal and typically only occurs during removal. When magnesite is broken up or ground, it can create fine dust. Like any construction dust, inhaling this can irritate the respiratory system. This is why professional removalists must use specialised dust extraction equipment and personal protective equipment (PPE). In short: Magnesite is not toxic to live on, but it must be removed by professionals to manage dust inhalation risks. The Real Culprit: Structural Dangers to Your NSW Property Here is the real danger of magnesite. The material is hygroscopic, meaning it loves to absorb and hold moisture. Sydney's humid climate, combined with inevitable water sources like bathroom leaks, kitchen spills, or even mopping, creates a perfect storm. The magnesite layer acts like a sponge, drawing in and trapping water against the concrete slab. This moisture contains chlorides, which are highly corrosive. The chlorides seep into the concrete and reach the steel reinforcement bars (rebar) embedded within the slab. This triggers a chemical reaction: corrosion. The steel rusts and expands, sometimes up to seven times its original size. This expansion forces the surrounding concrete to crack and break away. This process is commonly known as "concrete cancer" or spalling. Warning Signs Your Property May Be at Risk: Cracking or lifting floor tiles that sound "drummy" or hollow when tapped. Rust-coloured stains seeping up through tile grout or carpet. Persistent damp or musty smells coming from the floor. Concrete cracking or "spalling" (flaking or breaking) on the ceiling of the apartment below yours. Your building was constructed in Sydney between 1960 and 1989. How Can I Tell If My Sydney Apartment Has Magnesite? Unfortunately, you can't be 100% certain just by looking. The warning signs above are strong indicators, but they can also be caused by other issues. The only way to know for sure is through professional testing. A remediation specialist, like the team at Elyment Group, can take a small core sample of your floor. This sample is then sent to a lab to confirm the presence and composition of magnesite and to check the chloride levels in the concrete slab. You've Found Magnesite. What's the Next Step? Finding magnesite doesn't mean your building is about to collapse. But it does mean you need a plan. "The worst thing you can do is ignore it or, even worse, cover it up with new flooring," a specialist warns. "That just traps the moisture and accelerates the damage, making the final repair bill exponentially higher." A professional remediation plan typically involves: Inspection & Testing: Assessing the full extent of the magnesite and any existing concrete cancer. Safe Removal: Using specialised tools like concrete grinders with HEPA filter vacuums to remove the magnesite and any damaged concrete safely. Slab Remediation: Treating the exposed steel rebar to remove rust and applying protective coatings. Slab Repair: Repairing the damaged concrete to restore structural integrity. New Flooring System: Installing a new, waterproof, and modern flooring system. This is not a DIY job. It requires specialists who understand structural concrete repair and safe material handling. Key Takeaways for Sydney & NSW Homeowners Health Risk: Magnesite is not considered toxic to live on. The risk comes from dust during removal. Structural Risk: This is the major danger. Magnesite absorbs moisture, causing steel rebar to rust, which leads to "concrete cancer" and can compromise your building's structure. Warning Signs: Look for lifting tiles, rust stains, and cracking. If your apartment was built in Sydney in the 60s, 70s, or 80s, be suspicious. Action: Do not cover it up. Get a professional inspection and core test from a specialist remediation company. Protect Your Investment: Don't Wait for the Cracks to Show The presence of magnesite flooring is a serious issue for any Sydney strata committee or property owner. Proactive testing and early remediation can be the difference between a manageable repair and a catastrophic structural failure. WORRIED ABOUT YOUR FLOORS? GET A PROFESSIONAL ASSESSMENT .cta-container { text-align: center; margin-top: 30px; } /* CTA Button */ .elyment-cta-btn { background: linear-gradient(135deg, #022b5f, #0d1b2a); /* Gradient for depth */ color: #ffffff; border: none; padding: 14px 32px; border-radius: 6px; cursor: pointer; text-align: center; display: inline-block; font-family: 'Montserrat', sans-serif; font-weight: bold; font-size: 1.1rem; letter-spacing: 1px; text-transform: uppercase; text-decoration: none; transition: background 0.3s ease, box-shadow 0.3s ease, transform 0.2s ease; box-shadow: 0 4px 15px rgba(2, 43, 95, 0.4); position: relative; overflow: hidden; } /* Hover + Focus */ .elyment-cta-btn:hover, .elyment-cta-btn:focus-visible { background: linear-gradient(135deg, #16443e, #1b263b); box-shadow: 0 6px 20px rgba(22, 70, 138, 0.7); transform: translateY(-2px); outline: none; } /* Active state */ .elyment-cta-btn:active { transform: translateY(0); box-shadow: 0 3px 10px rgba(2, 43, 95, 0.5); } If you suspect your property might be at risk, it's time to get a professional assessment.