Crumbling mortar. Hairline cracks running through brick joints. White salt deposits blooming across the face of a 30-year-old apartment block.

If your strata building has any of these, you're not alone. Sydney's combination of salt air, driving rain, and temperature swings puts enormous strain on masonry — and most strata committees don't know the damage is there until it's already expensive to fix.

This guide walks you through how masonry damage develops in strata buildings, what the different repair options actually involve, what they cost, and how to evaluate a contractor before you commit.

Why Sydney Strata Buildings Are Particularly Vulnerable

Most of Sydney's strata stock was built between the 1960s and 1990s. That means decades of exposure to conditions that specifically attack masonry.

Salt-laden coastal air penetrates mortar joints and crystallises inside the brick. Each cycle of wetting and drying forces the crystals to expand, physically breaking the mortar from the inside out. Buildings within 5km of the coast — which covers most of Sydney's eastern, northern, and southern suburbs — experience this at an accelerated rate.

Thermal cycling is the other culprit. Sydney regularly swings 15–20°C within a single day. Brick and mortar expand and contract at different rates. Over 30+ years, those micro-movements crack the mortar bond and open pathways for water.

Water ingress follows. Once mortar joints fail, water enters the wall cavity. In a strata building, that water can track laterally through the masonry for metres before appearing as a damp patch inside someone's apartment — making it extremely difficult to pinpoint the source without investigation.

The result: by the time a strata committee sees visible damage, the underlying mortar deterioration is usually far more extensive than what's on the surface.

The Five Types of Masonry Damage in Strata Buildings

Not all masonry damage is the same, and the repair approach depends entirely on what's actually happening. Here's what to look for and what each type means.

1. Mortar Joint Deterioration (Repointing Required)

What it looks like: Mortar between bricks is recessed, crumbling, or missing entirely. You can scrape it out with a car key.

What it means: The mortar has reached the end of its service life. This is normal — mortar is designed to be the sacrificial element in a masonry wall (it's cheaper and easier to replace than bricks). In Sydney's climate, Portland cement mortar in exposed positions typically lasts 25–40 years before it needs repointing.

Urgency: Moderate. Deteriorated mortar doesn't cause immediate structural failure, but every season it's left unaddressed, water ingress worsens. In strata buildings, this often triggers secondary damage inside units — peeling paint, mould, warped joinery — which is far more expensive to remediate than the repointing itself.

2. Efflorescence (Salt Deposits)

What it looks like: White, powdery deposits on the brick surface. Sometimes heavy enough to look like the wall has been dusted with flour.

What it means: Moisture is moving through the masonry and carrying dissolved salts to the surface. The salt crystallises as the water evaporates. Efflorescence itself is cosmetic — the real concern is what's causing the moisture movement. Common sources: failed mortar joints, missing or cracked flashings, leaking balcony waterproofing above, or blocked weep holes.

Urgency: Low-moderate for the efflorescence itself, but the underlying moisture source needs investigation. Cleaning the salt off without fixing the source is a waste of money — it'll come back within weeks.

3. Brick Spalling and Fretting

What it looks like: The face of the brick is flaking off, crumbling, or breaking away in layers. Sometimes entire chunks fall from the wall.

What it means: Salt attack or freeze-thaw cycling has physically damaged the brick. Once a brick starts spalling, the exposed inner surface is softer and more porous, which accelerates the deterioration. In severe cases, individual bricks lose so much material that the wall's structural capacity is compromised.

Urgency: High for individual spalling bricks (they can't be repaired — they need to be cut out and replaced). If multiple bricks are spalling across a large area, the wall may need a comprehensive assessment to determine whether the damage is localised or systemic.

4. Structural Cracking

What it looks like: Cracks that run diagonally through both bricks and mortar joints (stair-step cracking), or long horizontal cracks along a mortar bed joint. Cracks wider than 2mm or cracks that are still moving (check by placing a small piece of tape across the crack and monitoring it over 4–6 weeks).

What it means: The wall is experiencing movement that exceeds its capacity. Common causes in strata buildings: differential settlement, inadequate or failed expansion joints, lintel failure above windows and doors, or thermal movement in long uninterrupted walls.

Urgency: High. Structural cracking requires engineering assessment before any repair is undertaken. The crack is a symptom — if you just fill it without addressing the cause, it'll crack again. Repairs typically involve crack stitching (stainless steel reinforcement bars epoxied across the crack) combined with addressing the root cause.

5. Render Failure

What it looks like: Render (cement or acrylic coating over masonry) is cracking, debonding, or falling away from the wall. Hollow sounds when tapped. Bulging sections.

What it means: The bond between render and substrate has failed, usually because of water behind the render, substrate movement, or the render mix being incompatible with the brick (common with old lime mortar bricks that were later rendered with rigid cement render).

Urgency: Moderate to high. Debonded render can fall from height — a safety hazard in a strata building, especially above common areas, footpaths, or car parks. The strata committee has a duty of care to address this promptly.

What Each Repair Actually Involves

Understanding the repair process helps strata committees evaluate quotes and set realistic expectations for duration and disruption.

Repointing

The process: old mortar is raked out to a depth of at least 15mm (typically using an angle grinder with a thin blade or specialised raking tool). The joint is cleaned, dampened, and new mortar is pressed in, then tooled to match the original profile.

Critical detail for strata buildings: the mortar type matters. Heritage buildings (pre-1930s) typically used lime mortar, which is softer and more flexible than modern Portland cement. Repointing a lime-mortar building with cement mortar causes the brick to become the weak point — it'll spall and crack. Any contractor quoting on a heritage-era strata building should be testing the existing mortar composition and matching it, not just using whatever's on the truck.

Typical cost: $50–$100+ per square metre, depending on access difficulty. Lime mortar repointing costs 30–50% more than cement mortar. Scaffold access for multi-storey buildings can add $15,000–$50,000+ depending on height and footprint.

Brick Replacement

Individual damaged bricks are carefully cut out, the surrounding mortar is cleaned, and a matching replacement brick is set in new mortar. For heritage buildings, sourcing matching bricks can take weeks — reclaimed brick suppliers or custom-fired bricks may be needed.

Typical cost: $80–$200 per brick replaced (including mortar match and pointing), plus access costs.

Crack Stitching

For structural cracks, slots are cut into the mortar bed joints above and below the crack, stainless steel reinforcement bars (typically 6mm helical bars) are epoxied into the slots, and the joints are repointed. This creates a reinforced band across the crack that restores tensile strength to the wall.

Critical detail: crack stitching addresses the symptom. The engineer should also specify a solution for the root cause — otherwise you'll get new cracks forming next to the stitched ones.

Typical cost: $200–$500 per linear metre of stitching, plus engineering assessment ($1,500–$5,000 depending on scope).

Render Repair

Failed render is removed, the substrate is prepared (cleaned, treated for salts, and bonded if needed), and new render is applied. For large areas, scaffolding is required. The new render must be compatible with the substrate — getting this wrong guarantees the repair will fail within 2–5 years.

For more information on render and facade repair options, see our facade remediation services.

Typical cost: $60–$120 per square metre (removal + new application), plus scaffold and access.

How Strata Committees Should Evaluate Masonry Repair Quotes

This is where most strata committees get caught out. Masonry repair looks simple from the outside — "just fix the bricks" — but the quality difference between a good repair and a bad one is enormous, and the bad one won't be obvious for 2–3 years until it fails.

What to look for in a quote

Methodology, not just price. A good quote describes the repair process step by step: mortar type, raking depth, brick matching process, scaffold plan, access method. A bad quote says "repoint brickwork — $X." If the quote doesn't describe how they'll do the work, they either don't know or don't care — either way, you'll get a poor result.

Mortar specification. For any building over 30 years old, the quote should mention mortar testing or mortar matching. If it doesn't, ask. Using the wrong mortar type is the single most common cause of masonry repair failure in older strata buildings.

Access plan. How are they getting to the work? Scaffold, swing stage (rope access), EWP (cherry picker)? The access method has a huge impact on cost, duration, and disruption to residents. Get specifics.

Scope clarity. Is the quote for the entire elevation, a specific area, or just the worst sections? Is brick replacement included if damaged bricks are found during repointing? What about lintel replacement if lintels are corroded? These are common extras that blow out budgets if they're not addressed upfront.

Red flags

• A quote that's significantly cheaper than all the others — masonry repair is labour-intensive and materials are relatively standard, so big price differences usually mean corners are being cut on scope or methodology.
• No mention of mortar type or matching.
• No site inspection before quoting (photos-only quotes for masonry work are unreliable).
• No mention of how they'll protect completed work during curing (mortar needs to cure for at least 3 days without heavy rain exposure).

The $30,000 Threshold

Under NSW strata law (updated April 2026), any work valued at more than $30,000 requires at least two independent quotes. For masonry repair on a multi-storey strata building, you'll almost always exceed this threshold once scaffold is included. Factor the quoting process into your timeline — getting two detailed masonry repair quotes takes 2–4 weeks minimum.

When to Act — and What Happens If You Don't

The economics of masonry repair are simple: early intervention costs a fraction of delayed intervention.

Repointing a section of deteriorated mortar joints on a low-rise strata block might cost $8,000–$15,000 including access. Waiting until water ingress has caused internal damage to three apartments means the masonry repair still costs the same, plus $20,000–$50,000+ in internal make-good (plaster, paint, joinery, mould remediation) across affected units.

For strata committees, there's also the question of liability. Under the NSW Strata Schemes Management Act, the owners corporation is responsible for common property — which includes exterior walls. If a committee is aware of deteriorating masonry and doesn't act, and that deterioration causes damage to lot property (individual apartments), the owners corporation may be liable for the repair costs to those lots.

The practical trigger: if your building is 25+ years old and hasn't had a masonry condition assessment, get one done. A suitably qualified remedial builder can inspect the exterior masonry, identify areas of concern, prioritise repairs, and give you a staged repair plan that fits within your capital works fund.

Getting Started

Masonry damage in strata buildings is progressive — the longer you leave it, the more expensive it becomes. The first step is understanding what you're dealing with.

A diagnostic assessment from an experienced remedial builder covers the full exterior masonry, identifies the type and extent of damage, tests mortar composition where needed, and provides a prioritised repair recommendation. From there, you can plan the work, budget through your capital works fund, and get proper quotes.

If your strata building has visible mortar deterioration, cracking, or salt deposits, get a free masonry assessment before the next wet season makes the damage worse.