Certified Engineering Design & Form 15 for Ancillary Structures
From custom carports, sheds, and elevated timber decks to retaining walls and swimming pools, our Chartered RPEQ engineers deliver safe, council-ready structural engineering and Form 15 certification across Southeast Queensland.
Ancillary Structure Engineering Services
Ostanes Engineering provides comprehensive RPEQ structural design, calculations, and Form 15 certification across all residential and commercial ancillary structures in Queensland.
Reinforced concrete pool shells (AS 2783:2025), out-of-ground walls, hydrostatic uplift design, and Form 15 certificates.
Portal-frame workshops, kit sheds, reinforced concrete foundation slabs, hold-down bolts, and site-specific wind design.
Structural framing design for elevated timber and steel decks, posts, joists, lateral bracing, and balustrade loads.
Freestanding and attached carport structural design, wind uplift resistance, footing connections, and Form 15 drawings.
Flyover and attached patio roof engineering, beam sizing, house connection brackets, and cyclonic wind design.
Reinforced core-filled block walls, masonry boundary fences, gate piers, wind overturning footings, and council compliance.
From Site Concept to
Council-Ready Form 15
1. Plans & Site Details
Share your site sketch, proposed dimensions, or manufacturer specs. We review your property constraints and provide a fixed-price engineering proposal within 24 hours.
2. Structural & Wind Analysis
Our RPEQ engineers calculate wind classifications (N1โN4 / C1โC3), footing sizes, member spans, and connection details to ensure structural safety and cost efficiency.
3. Certified Form 15 Delivery
Receive clear, builder-ready structural drawings and your signed RPEQ Form 15 compliance certificate ready for immediate private certifier submission.
Certified Ancillary Engineering Across Southeast Queensland
Ostanes Engineering provides certified structural engineering designs and site inspections for all ancillary structures across Brisbane, Gold Coast, Sunshine Coast, Logan, Moreton Bay, Ipswich, and Toowoomba. All designs strictly comply with the National Construction Code (NCC) and Australian Standards.
- RPEQ (Board of Professional Engineers QLD) & CPEng Registered
- AS 1170 & AS 4055 (Wind Loads for Housing & Outdoor Structures)
- AS 1684 (Timber Framing) & AS 4100 (Steel Structures)
- AS 4678 (Earth Retaining Structures) & AS 3600 (Concrete)
What Clients Say
After the Drawings Land
Everything you need to know about ancillary structure engineering
Comprehensive Engineering for Ancillary Structures in Queensland
Ancillary structures such as carports, sheds, decks, patios, pergolas, retaining walls, and swimming pools add tremendous functional and aesthetic value to residential and commercial properties. However, because these structures face extreme weather, high wind pressures, and variable ground conditions, Queensland local councils and private certifiers require rigorous structural engineering and signed RPEQ Form 15 compliance before construction begins.
At Ostanes Engineering, our Chartered RPEQ structural engineers deliver practical, cost-effective design solutions tailored to your property layout. We ensure all structures comply with the Building Code of Australia (BCA), Queensland Development Code (QDC), and relevant Australian Standards, preventing costly compliance disputes, site re-work, or council stop-work notices.
Carports, Garages & Industrial Shed Design
Whether installing a prefabricated portal frame steel shed or building a custom timber carport, determining the correct wind classification (AS 4055 / AS 1170) is essential. We calculate precise uplift forces, roof tie-downs, column sizes, and footing depths to ensure your garage or shed withstands severe storm events across Southeast Queensland.
Elevated Decks, Patios & Verandahs
Queensland’s outdoor lifestyle revolves around spacious decks and covered patios. In Queensland, decks higher than 1 metre above ground level require full building approval and engineering certification. We specify robust post connections, bearer and joist spans (AS 1684), balustrade loadings, and footing embedment into solid ground to guarantee structural safety for family and guests.
Retaining Walls & Earth Retaining Structures
Under Queensland regulations, retaining walls exceeding 1 metre in height, or retaining walls subject to surcharge loads (such as driveways, buildings, or slopes within a 1.5m zone), require structural engineering certification under AS 4678. We design concrete sleeper walls, core-filled masonry block walls, boulder walls, and geogrid-reinforced soil systems with comprehensive subsoil drainage to eliminate hydrostatic pressure build-up.
Swimming Pools & Building Near Easements
Constructing an in-ground swimming pool near an existing home or boundary requires careful foundation analysis (zone of influence). We provide certified structural calculations for concrete pool shells (AS 3600), fiberglass pool support foundations, and “build over sewer / stormwater” engineering approvals for utility authorities such as Urban Utilities and Gold Coast City Council.
Get In Touch
Get a certified ancillary structure design you can build with confidence
At Ostanes Engineering, we make council certification straightforward and fast. Speak directly with a Chartered RPEQ Structural Engineer today.
- (+61) 411 631 777
- info [at] ostanes-engineering [dot] com
- Sunnybank, QLD 4109
- Denham Court, NSW 2565
