Timber has a long history in construction. It is workable, widely available, and in certain environments it performs well. But Western Australia is not a forgiving environment for timber. Between termite pressure, bushfire exposure, coastal conditions and the compliance requirements that come with both residential and commercial builds, timber can create issues that continue long after handover.
If you are planning a residential or commercial project in WA, it is worth understanding what timber is working against before you commit to it.
Key Summary: Disadvantages of Timber in Construction
- Termites: Timber-framed builds in termite-prone areas require a compliant termite management system and an ongoing upkeep approach aligned to the installed system and the durable notice (NCC 2022 Housing Provisions Part 3.4, AS 3660.1:2014).
- Bushfire: In bushfire-prone areas, timber construction must meet progressively stricter requirements as BAL ratings rise, which can increase specification, detailing and compliance complexity (AS 3959:2018, NCC Part G5).
- Movement: Timber expands and contracts with moisture and temperature changes, which can create tolerance, lining and finishing issues, especially on large, modular or multi-storey builds.
- Commercial fire compliance: As building class and height increase, NCC fire requirements tighten and the compliance pathway for combustible materials can become more complex (NCC Volume 1 Section C, Table C2D2).
- Maintenance: Timber typically carries a higher ongoing maintenance burden (finishes, sealing, inspections, repairs) than many alternatives, especially in coastal and high-exposure locations.
1. Termite Risk Is a Regulatory Requirement, Not Just a Concern
Western Australia carries meaningful termite risk across much of the state. CSIRO research notes (Source: CSIRO — Managing Termites) termite risk tends to decrease from north to south, which places WA’s north, including the Pilbara and Kimberley, in higher-risk territory, while Perth metro and the south-west still fall within active risk zones. For timber framing, that risk is not just a maintenance concern. It is a compliance obligation embedded in the building code.
What the NCC requires
Under NCC 2022 Housing Provisions Part 3.4 (Termite Risk Management), any Class 1 or Class 10 building constructed in an area where subterranean termites present a known risk must include a compliant termite management system. This is referenced against AS 3660.1:2014 (Subterranean Termite Management, New Building Work), which sets out design and installation requirements for physical and chemical barriers.
Untreated standard timber framing does not meet the threshold for materials considered not subject to termite attack. Steel, by contrast, is explicitly listed as a material considered not subject to termite attack.
That means a typical timber-framed build in a WA termite risk area will require:
- A compliant termite barrier system installed during construction
- A permanent notice fixed to the building detailing the system type, installation date, and inspection requirements
- Ongoing inspections and upkeep in line with the installed system and notice
- Maintenance and replenishment where chemical reticulation is used
What this means in practice
Most home insurance policies do not cover termite damage. Repair bills can be significant, and the biggest risk is often the damage that occurs before activity is detected.
For commercial projects, termite management provisions still apply where relevant, and the compliance and ongoing management burden can scale with the size and complexity of the build.
Steel framing itself is not susceptible to termite attack, which can reduce the termite-management burden compared with timber framing (while other susceptible materials may still require appropriate protection).
2. Bushfire Compliance Adds Cost and Complexity
WA has extensive bushfire-prone land. The Perth hills, the south-west, the Great Southern and regional centres include significant areas where development is subject to a Bushfire Attack Level (BAL) rating. For timber, that can create real compliance and specification challenges.
How BAL ratings affect timber
AS 3959:2018 (Construction of Buildings in Bushfire-Prone Areas) is referenced in the NCC (NCC 2022 Part G5 ) as the Deemed-to-Satisfy pathway for certain building classes in designated bushfire-prone areas. The Standard defines six BAL categories: BAL-LOW, BAL-12.5, BAL-19, BAL-29, BAL-40 and BAL-FZ, representing increasing ember attack, radiant heat and direct flame exposure. Construction requirements increase at each step.
As BAL ratings rise, the use of standard timber becomes progressively more constrained:
| BAL rating | Timber status | What this means |
| BAL-LOW | Acceptable | No special construction requirements under AS 3959 |
| BAL-12.5 | Conditional | Ember protection detailing required; some timber elements restricted |
| BAL-19 | Restricted | Increased material restrictions; detailing requirements tighten |
| BAL-29 | Highly restricted | Some external elements must be non-combustible or comply via specified materials/systems; treatments and detailing requirements increase |
| BAL-40 | Very limited | Non-combustible materials are strongly preferred; standard timber is often unsuitable unless protected or specifically detailed to comply |
| BAL-FZ | Extremely limited | Very strict construction requirements; exposed combustible materials are heavily limited or must form part of compliant, fire-tested systems |
The commercial compliance challenge
For Class 2–9 buildings in designated bushfire-prone areas, NCC Part G5 applies. As BAL ratings increase, Deemed-to-Satisfy pathways can become more limited for some building types and sites, and projects may require a Performance Solution supported by fire engineering.
Steel is non-combustible, which can simplify compliance where combustible materials create additional constraints. That often reduces the need for material substitutions and specialised detailing required to make timber comply in higher BAL environments.
3. Timber Moves and That Creates Problems
Timber is hygroscopic. It absorbs and releases moisture in response to changes in temperature and humidity. In WA, where summer temperatures can exceed 40°C and conditions can swing between dry heat and coastal humidity, movement can be significant.
What this looks like on site
- Framing delivered in cooler, moist conditions can shrink once installed in a warm, enclosed structure
- Studs and plates can twist, bow or cup over time, affecting linings, tiling and joinery
- Tolerances that look acceptable at frame stage can turn into visible defects at finishing stage
- Joints can open, fixings can pull, and elements that were plumb at inspection may not remain that way
For standard residential builds, this is often managed through good practice and drying time. For more demanding applications such as modular construction, multi-residential projects and prefabricated panels, dimensional variability can create quality risks because alignment and stacking tolerances are tighter.
The maintenance chain
Movement in framing can drive downstream issues such as cracked render, grout line failures, sticking doors and warped trims. These problems often develop months after handover and can lead to rectification costs depending on when they emerge and how the contract allocates responsibility.
4. Commercial Builds Face Harder Fire Compliance Rules
For commercial and multi-residential projects, timber’s combustibility can increase compliance complexity beyond the bushfire question.
NCC Volume 1 Section C governs fire resistance for Class 2–9 buildings. Table C2D2 sets the minimum construction type required based on classification and rise in storeys. As building height and occupancy risk increase, construction type requirements tighten and the practical pathway for combustible materials can narrow.
Specifically:
- Where Type A construction is required, the use of combustible materials is more constrained, and timber often requires compliant fire-protection systems to satisfy requirements.
- Under NCC Clause C2D13, fire-protected timber may be used in certain circumstances subject to conditions and limitations, including effective height limits and cavity barrier requirements.
- For Class 9 buildings (childcare, health care, aged care), fire provisions are more stringent, and design and certification requirements can increase as buildings become taller or more complex.
What this costs
The fire compliance pathway for timber in larger or higher-occupancy buildings can involve fire engineering, additional lining systems, extra certification and higher labour inputs. In practice, some projects that begin with timber in mind shift to steel once the full compliance burden is understood.
5. Moisture, Rot and a Maintenance Burden
WA is often described as dry, and across much of the state that is true. But Perth’s coastal suburbs, the south-west and northern coastal areas experience meaningful humidity, salt air and moisture cycling that timber can struggle with unless it is well detailed and maintained.
For residential builds
- Untreated or inadequately sealed timber in exposed locations is susceptible to surface degradation, checking and eventual rot
- Subfloor timber in older Perth homes with raised floors often requires ventilation management and inspection
- Coastal salt air can accelerate deterioration and complicate fixing and connection specification
For commercial builds
- Larger floor areas and more exposed elements can increase the scale and cost of maintenance programs
- Repainting, re-sealing, pest inspections and structural checks need to be scheduled over the building’s life
- In food production, health care or early learning environments, deteriorating timber surfaces can create additional hygiene and asset management pressures
Steel framing does not rot or absorb moisture. In galvanised form, it can perform consistently in coastal and high-humidity environments, with reduced maintenance compared to exposed timber elements when appropriately specified.
6. Standard Timber Framing Has Limits at Commercial Scale
Residential framing operates within a relatively constrained structural envelope. Commercial projects, such as retail, industrial, childcare and multi-residential, often require clear spans, large openings and load-carrying capacity that can challenge standard timber framing without additional engineering intervention.
- Timber beams deflect under load more than steel equivalents of the same cross-section, often requiring deeper members or additional supports
- Larger clear spans often require engineered timber products such as LVL, glulam or CLT, which can carry a cost premium over standard framing material
- Connections in timber structures typically require more considered detailing to achieve comparable load transfer to steel connections
- In cyclonic wind regions, including parts of the Pilbara, Kimberley and Gascoyne, the engineering requirements for timber framing under AS 1684.3 can add complexity and cost as scale increases
Source: AS 1684.3:2021 (standards.org.au). AS 1684.3 is referenced in the NCC as a Deemed-to-Satisfy pathway for timber framing in cyclonic wind classifications C1, C2 and C3.
Light gauge steel framing offers consistent material properties, strong strength-to-weight performance and engineered connection systems, without timber’s moisture-driven dimensional variability.
What This Means for Your Project
Timber is not an inherently bad building material. But in Western Australia, it operates under environmental, regulatory and performance pressures that can add cost, complexity and long-term risk to both residential and commercial builds. Termite management is a serious consideration, bushfire compliance can be demanding, dimensional movement is real, and maintenance obligations can be significant over the life of the building.
For builders and developers working across WA, whether in Perth metro, coastal areas, the south-west or regional sites, understanding these constraints helps you make better structural decisions from the start.
At Steel Frames WA, we manufacture and supply precision light gauge steel framing for residential and commercial projects across Western Australia.
Our framing is non-combustible, termite-resistant, dimensionally stable and engineered to WA’s wind and climate conditions. If you are planning a project and want to understand how steel framing could work for you, get in touch with our team today.
FAQs
What are the main disadvantages of building with timber in Western Australia?
The main disadvantages of timber framing in WA include termite risk, bushfire compliance, moisture-related movement, ongoing maintenance, fire compliance on larger commercial projects and structural limitations for some long-span applications. These issues can increase the complexity, cost and maintenance requirements of a timber-framed building over its lifetime.
Is termite damage a major risk with timber framing in WA?
Yes. Subterranean termites are a recognised risk across much of Western Australia, including Perth and regional areas. Timber-framed buildings in termite-prone locations generally require a compliant termite management system, ongoing inspections and maintenance. Steel framing itself is not susceptible to termite attack, although other vulnerable materials in the building may still require protection.
Is timber framing suitable for bushfire-prone areas?
Timber can be used in bushfire-prone areas, but the requirements become more restrictive as the Bushfire Attack Level, or BAL, increases. Higher BAL ratings can require additional material specifications, detailing and protection measures. Because steel framing is non-combustible, it can simplify some aspects of construction in higher bushfire-risk areas.
Does timber framing warp, shrink or move over time?
Timber naturally absorbs and releases moisture, which can cause it to shrink, expand, twist or bow as environmental conditions change. In WA’s combination of dry heat and coastal humidity, this movement can contribute to issues such as cracked finishes, sticking doors, misaligned joinery and changes in framing tolerances. The risk can become more important in modular, prefabricated and multi-storey construction where precise alignment is required.
Does timber framing require more maintenance than steel framing?
Timber can require ongoing inspections and maintenance to protect it from termites, moisture, rot and deterioration. Exposed timber may also require sealing, repainting or repair over time, particularly in coastal or high-humidity locations. Properly specified galvanised steel framing does not rot or absorb moisture and can reduce some of these ongoing maintenance requirements.
What are the disadvantages of timber framing for commercial buildings?
Commercial buildings often require larger spans, openings and greater load-carrying capacity than standard residential construction. Achieving these requirements with timber can require deeper members, additional supports or engineered timber products such as LVL, glulam or CLT. Fire compliance can also become more complex as building height, classification and occupancy requirements increase.
