Structural · 7 min read
Timber, steel or concrete: choosing a structural system in Brisbane
Most residential and light commercial projects in Brisbane can be built in more than one material. The right choice depends on spans, wind region, corrosion exposure, buildability and what your builder does well — not on habit.
Timber
Fast, economical and familiar to every Brisbane carpenter. Designed to AS 1720 and AS 1684 for framing, with engineered timber (LVL, glulam) covering the longer spans that sawn timber cannot.
Watch durability class and termite protection, deflection on long joists and cantilevers, and tie-down continuity from roof to footing in high wind areas.
Steel
Steel to AS 4100 and cold-formed to AS/NZS 4600 handles long spans with slender members — the answer for removing a load-bearing wall, opening up a rear elevation, portal frame sheds and mezzanines.
Connections are where steel projects succeed or fail. Base plates, anchor bolts, welded and bolted details and corrosion protection near the coast all belong on the drawings, not left to site.
Concrete and masonry
Reinforced concrete to AS 3600 for slabs, suspended floors, basement and retaining structures, transfer beams and pools. Reinforced masonry to AS 3700 for load-bearing and retaining walls.
Slab design starts with the soil classification under AS 2870 — site class drives slab type, and getting that wrong is the most common cause of later cracking.
Wind, tie-down and the load path
South East Queensland sits in wind region B, and terrain, shielding and topography can push a suburban site well above the default. Uplift, not gravity, governs many roof and connection details, and the load path must be continuous from sheeting to footing.
Design fees
Single storey design from $1,200. Double storey from $2,200. Extensions and structural modifications from $1,100. Sheds and carports from $1,000. Warehouses, commercial structures and unusual structures are quoted free on the plans.
Frequently asked questions
- Do I need an engineer to remove a load-bearing wall?
- Yes. The replacement beam, its supports and the load path down to the footings all need design and certification, and your certifier will ask for it.
- What do you need to quote a house design?
- Architectural or draft plans, the site address, the soil report if you have one, and anything unusual you already know about the site.
Send your plans for a fixed structural design fee.
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