If you’re buying a property in Perth, knowing what defects are most likely to be lurking behind the walls and what they’ll cost to fix could save you tens of thousands of dollars. At Bestwest Building, we’ve completed over 45,000 building inspections across Perth and South West WA. In that time, we’ve seen the same defects come up again and again, in properties of all ages, types, and price ranges.
This guide covers the 10 most common defects our inspectors find, what causes them, what to look for, and importantly what they typically cost to rectify in Perth’s current market.
| IMPORTANT NOTE This guide is based on our inspectors’ real-world experience across Perth and South West WA. Every property is different, and the cost ranges below are indicative only. A professional building inspection is the only way to accurately assess the condition of any specific property. Get a quote at bestwestbuilding.com.au |
1. Roof Defects; The #1 Issue in Perth Homes
Deteriorating ridge & hip tile pointing.
Roof defects are, without question, the most common issue we find in Perth properties. Whether it’s a tile roof, Colorbond, or metal sheeting, the heat, UV exposure, and occasional heavy rainfall in Western Australia create the perfect conditions for premature roof deterioration.
Common roof defects we find:
- Cracked, slipped, or broken roof tiles
- Damaged or missing pointing and bedding around ridge tiles
- Deteriorated flashing around skylights, chimneys, and penetrations
- Blocked or damaged gutters and downpipes
- Sagging or damaged roof sheeting
| Issue / Repair Type | Typical Perth Cost Range |
| Replace individual broken tiles | $200 – $500 |
| Full repoint and rebedding of ridge tiles | $2,000 – $5,000 |
| Gutter replacement (full perimeter) | $2,500 – $6,000 |
| Full roof replacement (tiles) | $15,000 – $35,000+ |
2. Rising Damp and Moisture Issues
Moisture ingress/damp to wall behind shower.
Perth’s building stock includes a large proportion of older brick homes, particularly in inner suburbs where original damp-proof courses have failed or were never properly installed. Moisture is one of the most destructive forces a building faces, and it often hides in plain sight.
Signs our inspectors look for:
- Tide marks or salt crystallisation (efflorescence) on lower walls
- Peeling paint or bubbling render at skirting height
- Musty odours in enclosed spaces
- Staining on ceilings beneath bathrooms or wet areas (two storey homes)
- Soft or spongy flooring near wet areas
Moisture issues are also one of the most underestimated defects by buyers. What looks like a cosmetic paint problem is often a symptom of a much larger issue. Our moisture meter devices and thermal imaging inspection service can detect moisture behind walls that isn’t visible to the naked eye.
| Issue / Repair Type | Typical Perth Cost Range |
| Damp-proof injection treatment | $1,500 – $4,000 |
| Bathroom waterproofing and retiling | $3,000 – $8,000 |
| Subfloor drainage remediation | $2,000 – $6,000 |
| Structural damage from long-term moisture | $10,000 – $50,000+ |
3. Structural Cracks
Structural cracks to brickwork.
Not all cracks are created equal. Fine hairline cracks in render or plasterwork are common in any building and often cosmetic. But diagonal cracks at door and window corners, wide cracks in brickwork, or cracks that have been painted over multiple times can indicate more serious movement, that’s where a qualified inspector’s eye matters enormously.
Perth’s sandy soils are particularly prone to seasonal movement, and homes built on poorly prepared sites can show significant foundation movement over time. We pay particular attention to cracks in garages, an area where significant structural issues are often first visible but frequently overlooked.
| Issue / Repair Type | Typical Perth Cost Range |
| Cosmetic crack repair (render/plaster) | $500 – $2,000 |
| Brickwork repointing and repair | $2,000 – $8,000 |
| Underpinning / foundation stabilisation | $15,000 – $60,000+ |
4. Roof Frame Defects (What You Can’t See From The Ground)
Cracked ridge board located in the roof frame.
This is one of the most important differentiators when choosing a building inspector: does your inspector physically enter the roof space, or just inspect from the access hatch? At Bestwest Building, our inspectors enter the roof frame wherever safely possible, what we find there regularly shocks buyers.
Common roof frame defects we find:
- Hanging beams with no structural support
- Sagging or inadequate bracing
- Termite damage to structural timbers
- BCA non-compliance defects in new builds… yes, brand new homes have these too
- Unauthorised modifications to the roof frame structure
A compromised roof frame can cause serious structural issues. The good news: when we identify these defects during a pre purchase building inspection, sellers are typically obligated to rectify them at their own cost before settlement.
| Issue / Repair Type | Typical Perth Cost Range |
| Engineer’s assessment report | $800 – $2,000 |
| Roof frame repair / re-bracing | $2,000 – $8,000 |
| Major structural roof frame repair | $8,000 – $25,000+ |
| Full roof frame replacement (severe cases) | $20,000 – $50,000+ |
5. Timber Pest Damage (Termites)
Significant termite damage found on exterior cladding.
Western Australia has one of the highest termite activity levels in the country. Perth’s warm climate and prevalence of older timber-framed structures make termite damage a very real risk for any buyer. Crucially, termites often cause significant structural damage before any visible signs appear on the surface.
A separate timber pest inspection should always accompany your building inspection. Bestwest Building offers combined building and pest inspections; a single booking, single visit, full picture.
What a timber pest inspection covers:
- Visible assessment for evidence live termite activity and past activity
- Termite entry points and conditions conducive to infestation
- Wood decay fungi and other timber pests
- Assessment of existing termite management systems
| Issue / Repair Type | Typical Perth Cost Range |
| Preventative Termite treatment (chemical barrier) | $1,500 – $3,000 |
| Structural timber repair after termite damage | $5,000 – $30,000+ |
| Full subfloor timber replacement (severe cases) | $15,000 – $50,000+ |
6. Electrical Issues
Exposed electrical wiring found in the roof frame. Referred to electrician for further assessment.
Old or non-compliant electrical wiring is a safety risk and a very common finding in Perth’s older homes. Our inspectors identify visible and accessible electrical concerns, however any specific issues flagged should then be assessed by a licensed electrician.
Common electrical issues we identify:
- Outdated rubber-insulated wiring in pre-1970s homes
- Unsafe or unlicensed DIY electrical work
- Absence of safety switches (RCDs) which is mandatory in WA for all new circuits
- Non-compliant or overloaded switchboards
- Exposed wiring or unsafe connections in roof space or subfloor
| Issue / Repair Type | Typical Perth Cost Range |
| Safety switch (RCD) installation | $200 – $400 |
| Full switchboard upgrade | $2,000 – $5,000 |
| Rectification of unlicensed DIY wiring | $1,000 – $4,000 |
| Rewiring of older home (full) | $8,000 – $20,000+ |
7. Plumbing Defects
Leaking tap spindle.
Plumbing issues are extremely common in Perth properties, particularly those built before 1990. Many buyers focus on the visible; taps, showerheads, toilets and miss the issues that are harder to see but far more expensive to fix.
Key plumbing concerns our inspectors flag:
- Leaking taps, fixtures, and shower recesses
- Hot water systems approaching or past end of life (typically 8–12 years)
- Evidence of previous leaks; staining, soft flooring, warped cabinetry
- Stormwater drainage concerns
- Corroded or failing pipes (particularly in older galvanised steel systems)
| Issue / Repair Type | Typical Perth Cost Range |
| Hot water system replacement | $1,200 – $3,500 |
| Burst or leaking pipe repair | $500 – $3,000 |
| Blocked or deteriorated stormwater drainage | $1,000 – $8,000 |
| Shower recess waterproofing and retile | $2,500 – $6,000 |
| Full re-pipe of older home | $8,000 – $20,000+ |
8. Retaining Wall Issues
Significant cracking found in a retaining wall.
Perth’s undulating suburbs, particularly in the hills and southern corridor, have a high prevalence of retaining walls, many of which are at or past their structural lifespan. This is an area buyers frequently overlook because walls often look fine visually until they fail.
Leaning, cracking, or bowing retaining walls are a safety risk and can involve significant council compliance obligations. Walls over a certain height in WA require engineer certification, and responsibility passes to the new owner at settlement.
| Issue / Repair Type | Typical Perth Cost Range |
| Retaining wall repair (minor lean or cracking) | $1,500 – $5,000 |
| Retaining wall replacement (per lineal metre) | $400 – $1,200 |
| Engineer’s compliance report | $800 – $2,000 |
| Full retaining wall rebuild (long run) | $8,000 – $30,000+ |
9. Asbestos-Containing Materials
Potential asbestos containing material found and testing recommended.
Homes built before 1990 in Perth may contain asbestos in fibrous cement sheeting (eaves, wet areas, fencing), textured ceilings, and floor coverings. Our inspectors identify suspected asbestos-containing materials and recommend specialist testing.
Asbestos that is in good condition and undisturbed may be left in place, it’s only when it becomes damaged or is disturbed that it poses a health risk. However, any removal must be carried out by a licensed asbestos removalist.
Where we commonly find asbestos in Perth homes:
- Fibrous cement eave lining (particularly 1960s–1980s homes)
- Textured ‘popcorn’ or sprayed ceilings
- Vinyl floor tiles and the adhesive beneath
- Fencing and outbuilding sheeting
| Issue / Repair Type | Typical Perth Cost Range |
| Asbestos testing (lab analysis per sample) | $50 – $150 |
| Licensed removal — non-friable sheeting (per m²) | $50 – $150 |
| Eave replacement after asbestos removal | $3,000 – $8,000 |
| Whole-house asbestos survey and removal | $10,000 – $40,000+ |
10. Non-Compliant Additions and Extensions
Unapproved patio structure noted and further clarification recommended.
Unauthorised additions; garages, granny flats, carports, decks, and room conversions, are remarkably common in Perth properties. If a structure was built without council approval or doesn’t comply with the Building Code of Australia, it becomes the new owner’s problem the moment they settle.
Our inspectors flag any structures that appear to be additions since construction or that show obvious compliance concerns. It’s then up to buyers to request documentation from the seller or seek council records before proceeding.
Common unauthorised additions we find:
- Garage conversions to habitable rooms (no building permit, poor insulation, non-compliant electrical)
- Carports and pergolas built without permits or beyond setback requirements
- Granny flats and sleepouts without correct approvals
- Decks, patios, and alfresco areas over height or size thresholds
- Swimming pools without current compliance certificates
| Issue / Repair Type | Typical Perth Cost Range |
| Retrospective building approval application | $2,000 – $5,000+ |
| Structural upgrades to achieve compliance | $3,000 – $15,000 |
| Demolition of non-compliant structure | $3,000 – $15,000 |
| Council fines (if enforcement action taken) | Varies — potentially significant |
Don’t Leave It to Chance – Get a Bestwest Building Inspection
The defects in this list represent the most common issues we find across Perth and South West WA, but every property is different. A professional building inspection is the only way to understand exactly what you’re buying before you commit.
Bestwest Building’s team of registered builders has completed over 45,000 inspections across Perth, the South West, and beyond. We enter roof spaces, we use moisture meters and thermal imaging, we provide same-day reports and we’re here to talk you through every finding.
Get a free 24/7 quote at bestwestbuilding.com.au or call us on (08) 9444 9562.
Frequently Asked Questions About Building Inspections in Perth
A standard pre-purchase building inspection in Perth typically costs between $595 and $895, depending on the size and type of property. A combined building and pest inspection generally ranges from $790 to $1090 for standard properties. Always check what’s included, at Bestwest Building, your inspection includes a same-day digital report with photos and a consultation with your inspector. Get an instant personalised quote at bestwestbuilding.com.au
You don’t have to be present, as we have such a fine-tuned inspection and reporting process we ensure you receive all of the information and defects that we find. You are more than welcome to speak to your real estate agent about being present during the inspection, however they may deny your request as they may not be present themselves and/or the seller of the property may be providing access for us.
Not necessarily. Finding defects that you didn’t know about is the entire purpose of a building inspection. In most cases, defects are either negotiating tools (to reduce the purchase price or have the seller rectify before settlement) or help you make an informed decision about whether the property is right for you. Your inspector can help you understand which findings are serious and which are routine maintenance items.
No… and this is a critical point. In Western Australia, there is no government licensing requirement for building inspectors. Anyone can call themselves a building inspector. This is why you must check your inspector’s actual qualifications. Bestwest Building’s team of inspectors are all registered builders with over 200 years of combined building experience, and all inspections are conducted in accordance with Australian Standard AS4349.1.
A standard residential building inspection typically takes 1–3 hours, depending on the size and age of the property. Larger homes, properties with multiple outbuildings, or older homes with complex issues may take longer. Your report is typically emailed the same day for most domestic properties.
