When Should You Worry About Cracks in Plaster Walls?

Most fine cracks in plaster are cosmetic and can be filled in. However, a crack is worth investigating before you repair it when it is wide, growing or recurring, or when it runs diagonally or steps through brickwork. The same goes for any crack that appears alongside sticking doors, noticeable floor changes or new gaps between walls and ceilings.

No single feature proves a crack is structural, but that combination is a reason to have it looked at rather than filled over.

Key Takeaways:

• Fine cracks can develop as plaster dries and shrinks, or as framing responds to moisture and temperature. This kind of cracking is common and rarely means trouble.
• Width is a useful guide, but only one factor. Pattern, location, whether the crack is growing, and nearby doors and floors all matter too.
• Solid plaster and plasterboard crack in different ways, though neither tells you the cause on its own.
• Filling the same crack again and again without asking why it keeps returning is a common mistake. Recurrence is a reason to investigate first.
• The crack-width categories in the Australian Standard for slabs and footings (AS 2870) are a useful reference for damage severity, not a test for whether a crack is structural.
• If a crack has you second-guessing, a building inspection can assess it and help you decide whether further investigation is warranted.

Fine cracks can develop as plaster dries and shrinks, as framing responds to changes in moisture and temperature, or as a house settles, and rarely amount to anything.

Cracks worth a second look can involve other factors, including movement in the ground beneath the home. This is a consideration across much of Queensland, where reactive clay soils swell and shrink with the weather. Not every plaster crack is a plastering job, and here is how to tell the difference.

Solid Plaster or Plasterboard? Why the Difference Matters

Not all walls people commonly call “plaster” are the same, and the type you have changes how you read a crack.

Solid plaster is a wet mix applied in coats over masonry or timber lath. It is dense and hard, and tends to crack in fine, sometimes long lines when the wall behind it moves or the plaster ages. It is common in older homes, though not only in them.

Plasterboard (gyprock or drywall) is a gypsum core wrapped in paper and fixed to the framing. It tends to crack along the joints between sheets, at the corners of doors and windows, or where the tape over a joint lifts, often from framing movement or the taping itself.

Knowing which you have helps you interpret a crack. A fine crack along a plasterboard joint is more likely to be cosmetic, while a crack cutting diagonally across a solid plaster wall is worth a closer look. Neither pattern confirms the cause on its own.

Hairline Cracks vs Structural Cracks: How to Tell the Difference

The Australian Standard for residential slabs and footings (AS 2870) sets out a classification of damage to walls, in which crack width is one factor. The CSIRO’s homeowner guide to foundation maintenance reproduces that table. Its categories, with the standard’s own descriptions summarised, run as follows:

• Category 0, under 0.1mm. Hairline cracks. Negligible.
• Category 1, under 1mm. Fine cracks that do not need repair.
• Category 2, under 5mm. Cracks are noticeable and may be easily filled; doors and windows may stick slightly.
• Category 3, 5mm to 15mm (or several cracks 3mm or more in one group). Cracks can be repaired, possibly with a small amount of wall replaced; doors and windows stick and service pipes can fracture.
• Category 4, 15mm to 25mm. Extensive repair involving breaking out and replacing sections of wall; frames distort, and walls may lean or bulge.

It is worth being clear about what these categories tell you. They describe how significant the damage is, but they are not a test for whether a crack is structural. Greater width can warrant closer attention, while fine, stable cracking is more often cosmetic. A narrow crack that is growing can matter more than a wider one that has been stable for years, which is why pattern, location and progression sit alongside width.

Plaster cracks: more likely cosmetic vs worth investigating

Feature	More likely cosmetic	Worth investigating
Width	Fine, up to about 1mm	Wide, roughly 5mm or more
Direction	Vertical, or along a plasterboard joint	Diagonal, stair-stepped, or horizontal in brickwork
Shape	Even width along its length	Noticeably wider at one end
Progression	Stable, not changing	Growing, or returning after repair
Other signs	Nothing else going on nearby	Sticking doors, noticeable floor changes, new gaps at ceilings

Can You Just Fill Hairline Cracks in Plaster?

Often, yes. If a crack is fine, has been stable, and runs vertically or follows a plasterboard joint with nothing else unusual around it, it may be suitable for routine filling and repainting as part of normal home maintenance.

The usual approach is to rake out the crack slightly, fill it with a flexible filler, then sand and paint. On a plasterboard joint, a flexible filler copes with small seasonal movement better than a hard-setting one.

The important part is checking the crack before you repair it. Filling is appropriate when a crack is genuinely cosmetic. If you have filled the same crack before and it keeps coming back, that is worth attention: recurrence is a reason to investigate the cause rather than fill it again.

A Simple Check Before You Fill

Many minor cracks can be managed as routine maintenance. This quick check helps you tell which ones might need more than that. Before filling a crack, look at whether:

• It is getting wider or longer over time
• It is noticeably wider at one end than the other
• It runs diagonally, steps through brickwork, or is horizontal in a masonry wall
• It is accompanied by doors or windows that have started to stick
• New gaps are opening around ceilings, walls or door and window frames
• There are similar cracks elsewhere in the home

Fine cracking where the wall meets the cornice can be common, particularly in older homes. New or widening gaps at the wall-ceiling junction, though, are worth investigating.

If the crack is fine, stable and isolated with none of these signs, routine filling may be all it needs. If several signs show up together, it is worth getting the cracking assessed before you repair it. That is where a building inspection helps. An inspector considers the cracking alongside other visible signs throughout the property, including the doors, floors, walls and ceilings, and can help you decide whether further investigation is warranted.

Get a Professional Opinion

Not every plaster crack is a plastering job. Inspect My Home’s inspectors work across Queensland and assess visible cracking as part of a pre-purchase or standard building inspection, carried out to the Australian Standard for property inspections (AS 4349.1). The report sets out visible findings and whether further investigation may be needed, in plain English within 24 hours [4].
If you have a crack you are unsure about, book a building inspection or call 1300 337 447 before you repair it.

Frequently Asked Questions

When should you worry about cracks in plaster walls?
Fine, stable cracks on their own are rarely a concern. Treat a crack as worth investigating if it is wide, growing, or shows up with other signs of movement such as sticking doors or new gaps at the ceiling.

How can you tell if a crack is structural?
You cannot confirm the cause from any single feature, which is the key point. Diagonal patterns, cracks wider at one end, and cracks that reopen after repair can all be associated with movement, but none proves it. Establishing whether cracking is structural usually needs an assessment of the whole property, not just the crack.

Can you just fill hairline cracks in plaster?
If a crack is fine, stable and cosmetic, it may be suitable for routine filling and repainting: rake it out, use a flexible filler, then sand and paint.

Why does the same crack keep coming back after I fill it?
Recurrence has more than one possible cause. It can indicate ongoing movement behind the wall, but it can also come down to the repair method or movement at a plaster joint. Rather than filling it a third time, it is worth having the cause looked at.

Do older homes crack more than newer ones?
They tend to crack differently. Older homes with solid plaster can show fine, long cracks as the plaster ages, though the same homes can also crack in response to movement. Newer homes crack too, often from shrinkage and settling early on. Age alone does not decide whether a crack matters, which is why the same warning signs apply whatever the age of the home.

Should I get a building inspection for a wall crack?
Not necessarily. If a crack is fine, stable and isolated, it may simply be cosmetic. If it is growing, recurring, or accompanied by other signs of movement, an inspection can help determine whether further investigation is warranted before you commit to repairs.

Many buyers assume an apartment doesn’t need the same scrutiny as a house. It’s smaller, often newer, and the common areas are generally managed through the strata scheme. But apartments can still have defects and other issues, making a building and pest inspection worthwhile. It also differs from an inspection of a freestanding house and doesn’t replace checking the wider strata scheme.

This article covers what an apartment inspection includes, its limitations, how it differs from a strata report, and what you may end up spending.

Key Takeaways

• Apartments and units can still have defects, water ingress and pest issues, so a building and pest inspection is worth considering.
• An inspection focuses on your individual lot and any accessible common property, but it cannot assess everything in the wider building.
• A building and pest inspection checks physical condition, while a strata report covers the scheme’s financial and administrative records. They provide different information.
• For a more complete picture, apartment buyers may want both an inspection and a strata records search.
• Inspection costs vary depending on the property and scope, so it’s best to get a quote for the specific unit.

Do apartments and units need a building and pest inspection?

Short answer: yes, in most cases.

An apartment may have fewer rooms and less land to inspect than a house, but that doesn’t necessarily mean fewer things can go wrong. Water ingress, waterproofing failures, poor drainage, cracking and pest activity can all affect apartments, including newer buildings.

There’s also the added complexity of shared building elements. A leak or defect may originate outside your lot but still affect your apartment, while responsibility for common property doesn’t necessarily mean you won’t face costs when major repairs are needed. Levies or special levies may be required to fund significant works.

A building and pest inspection gives you a clearer picture of the apartment’s physical condition before you commit to the purchase. If you’re weighing up an apartment purchase and want a professional set of eyes across it, you can book a building and pest inspection.

What’s covered in an apartment inspection (and what’s not)

Your inspection primarily assesses the individual apartment, along with any common property that is accessible and included within the inspection scope. The inspector generally won’t have access to neighbouring apartments or concealed areas, even where they may affect your property.

There are real limits to that access, and it’s worth understanding them before you book so the report doesn’t surprise you.

Covered in a typical apartment inspection:

• The interior of your unit: walls, ceilings, floors, windows, and doors
• Visible signs of moisture, water damage, and past leaks
• Cracking and signs of structural movement within the lot
• Accessible wet areas and visible plumbing fixtures
• Signs of termite activity and conducive conditions within reach
• Accessible common property, where included in the inspection scope and reasonably accessible

Not covered, or only partially:

• Inside neighbouring units, which are generally outside the inspector’s access and inspection scope
• Concealed pipework: shared plumbing and drainage can create risks such as leaks or water ingress, but pipework hidden behind walls or inside other lots is generally outside the scope of a visual inspection
• Roof spaces and service areas that are locked, sealed, or unsafe to access
• The building’s financial position, insurance, and maintenance records
• Any defect hidden behind finishes, fixtures, or stored belongings

These limitations are particularly relevant in apartments, where a moisture problem can originate in another unit or a shared building element and still affect your property. Your inspection covers what can be seen and safely accessed on the day, so concealed problems or areas outside the inspection scope may require further investigation.

For a more complete picture of the wider building, the inspection should be considered alongside a strata report.

Building & pest inspection vs strata report: what’s the difference

These two reports are sometimes confused. They serve different purposes, and one does not replace the other.

• A building and pest inspection is a physical assessment of the property’s condition, carried out on-site by a licensed and insured inspector who examines what’s accessible.
• A strata report reviews the records of the strata scheme and is also called a strata records report, or body corporate records search depending on the state or territory. It can include the scheme’s finances, meeting minutes, by-laws, insurance, and records of disputes and repairs.

Buyers or their representatives may be able to access these records as part of due diligence, depending on the state or territory and the circumstances of the purchase.

Here’s how they compare.

	Building & pest inspection	Strata report
What it checks	Physical condition of the lot and accessible common areas	The owners corporation or body corporate’s financial and administrative records
How it’s done	On-site inspection by a licensed and insured inspector	Review of the owners corporation or body corporate records
Can identify	Cracking, water damage, termite activity, defects	Special levies, fund balances, disputes, planned works
What it can’t see	The building’s finances and records	Anything physical the records don’t mention
Best used for	Understanding the condition of what you’re buying	Understanding the scheme’s financial position and recorded issues

The reason apartment buyers often use both comes down to how information is split in a strata scheme. A building and pest inspection shows you the current physical condition of the property, while a strata report can help you understand recorded issues, known upcoming costs, and the scheme’s financial position.

If you’d like both sides covered, you can get a quote and ask about arranging a building and pest inspection alongside a strata records search.

What building inspectors look for in apartments

The fundamentals are similar to a house inspection, but a few things get particular attention in a multi-unit building because of how apartments are built and shared.

• Water ingress and waterproofing. Bathrooms, balconies, and laundries warrant particular attention, and a leak in a wet area can affect the unit below. Inspectors look closely at these zones.
• Cracking and movement. Cracks in internal walls can be cosmetic or a sign of something structural. The inspector assesses what’s visible and flags anything that needs a closer look.
• Shared walls and ceilings. Moisture and pests can move through or around shared building elements, so these boundaries warrant particular attention.
• Termite activity and conducive conditions. Being above ground does not automatically eliminate termite risk. Depending on the building and surrounding conditions, an inspection can identify visible termite activity or conditions that may increase the risk of termite attack.
• Accessible common property. Where the inspector can reach shared areas within the inspection scope, these are assessed too.

The goal is to give you a clear picture of what you’re buying, with visible defects documented and explained so you can make an informed decision.

Cost of a building and pest inspection for an apartment

The cost depends on factors such as the property’s size, location, type of building, and the scope of the inspection, including whether building and pest are combined into one visit.

As an indicative guide, building inspections start from around $330 and a combined building and pest inspection from around $400 (inclusive of GST). These are a starting point only, and the price for a particular unit depends on its size, age, type, and location.

For a price on the exact unit you’re looking at, request a quote and the team can talk you through what’s included.

A quick checklist before you book

A few things worth confirming when arranging an inspection on an apartment or unit:

• Confirm what areas are included in the inspection
• Confirm whether accessible common property is inspected
• Check whether building and pest are included together
• Ask about any access requirements for the day
• Arrange a strata records search separately, as a records report is a different process

Do you need to be present for the inspection?

No, you don’t have to attend. However, being there for at least part of the inspection lets you see any issues firsthand and ask questions.

If you can’t attend, you’ll still receive a detailed written report, and the inspector can talk you through the findings by phone afterwards.

Buying vs rental inspections: A pre-purchase building and pest inspection checks the property before you buy. A rental inspection is carried out by the landlord or property manager during a tenancy.

Frequently Asked Questions

What do building inspectors look for in apartments?
They assess the physical condition of your lot and any accessible common property: water ingress and waterproofing, cracking and signs of movement, shared walls and ceilings, termite activity and conducive conditions, and visible defects in fixtures and finishes. Access to neighbouring units and concealed areas is limited.

What does a building and pest inspection cost?
It depends on the property’s size, location, type of building, and whether building and pest are combined into one visit. As an indicative guide, building inspections start from around $330 and a combined building and pest inspection from around $400 (inclusive of GST), but there’s no flat rate, so the best approach is to request a quote against the specific unit.

Do I need to be present for a building and pest inspection?
No. Many buyers like to be there for part of it to ask questions in context, but it’s not essential. If you can’t attend, you’ll still receive a detailed report and the inspector can walk you through it by phone.

Can a building and pest inspection identify defects in common property?
Only where the common property is reasonably accessible and within the inspection scope. Depending on the inspection scope, an inspector may assess shared areas they can safely reach, but concealed elements, and anything inside other lots, fall outside a visual inspection. The wider building is where the strata report can provide additional context through the scheme’s records.

Do I need both a strata report and a building and pest inspection?
For most apartment and unit purchases, the two work best together. A building and pest inspection assesses the physical condition of the lot and accessible common areas, while a strata report reviews the scheme’s financial and administrative records. Each covers ground the other can’t, so relying on one alone can leave a gap in your due diligence.

Booking an inspection

Buying an apartment is a big commitment, and a building and pest inspection gives you a clearer picture of its physical condition before you make a decision. Paired with a strata report, it provides information about both the property itself and the wider scheme.
If you’re unsure what you need for a particular unit, the team can help you. Book a building and pest inspection or call 1300 337 447, and you’ll have a detailed report back within 24 hours.