Residential Extension | Raby Bay
At Raby Bay on Moreton Bay, the homeowners wanted to open up their outdoor living space and keep their views across the water, with no posts breaking the sight lines. Network Steel built an 18-metre structural steel truss, cantilevered to create a 10 x 15-metre clear span roof. The overhanging structure added outdoor living space and framed the view rather than blocking it.
How do you build a roof extension without support posts blocking the view?
You cantilever it. A cantilever carries the roof from one anchored end, so the far edge can reach out over the space with nothing holding it up underneath. That is what keeps the sight lines clear. At Raby Bay, an 18-metre steel truss did the work, cantilevered out to form a 10 x 15-metre clear span roof over the outdoor living area. Getting the balance right across a span like that is an engineering job, which is why Network Steel worked with the builder, project architect and engineer from concept to completion.
What size steel is used for a cantilevered roof like this?
Heavy sections, fabricated to carry the load out over the span. The main truss measured 18m x 3m and was fabricated in two sections from a combination of steel beams and heavy steel angles. Once positioned, it interconnected with and solely supported a 610 UB 101 running 15 metres in the opposite direction. That is a substantial member doing a substantial job, which is what a clear span of this size demands.
How do you protect structural steel in a bayside location?
You galvanise it. Salt air off the bay is highly corrosive, so the entire truss assembly was fully galvanised using the hot dip method for long-term protection in a seaside environment. On a waterfront build, the coating is what keeps the steel sound for the life of the structure.
How do you install a large steel truss over an existing house?
Carefully, and with the right lift planned in advance. The process started with a full site measure, then detailed drawings from Network Steel. Once the project engineer approved the drawings, the trusses were manufactured and galvanised, then delivered to site.
Project at a glance
| Detail | |
|---|---|
| Project | Residential extension, cantilevered roof over outdoor living |
| Location | Raby Bay, Moreton Bay, QLD |
| Delivered with | Builder, project architect and engineer |
| Main truss | 18m x 3m, cantilevered, fabricated in two sections |
| Truss make-up | Steel beams and heavy steel angles |
| Clear span roof | 10 x 15 metres |
| Counter-span member | 610 UB 101, running 15 metres, solely supported by the truss |
| Steel finish | Hot dip galvanised [confirm to AS/NZS 4680] |
| Install | 80-tonne crane, lifted over an existing two-storey home |
| Delivery | Wide-load freight |
FAQ
Can you build a roof or extension with no support posts?
Yes. A cantilevered steel structure carries the roof from an anchored end, so the outer edge needs no posts underneath. This keeps views and sight lines clear. At Raby Bay, an 18-metre cantilevered steel truss created a 10 x 15-metre clear span roof.
How far can a steel roof cantilever?
It depends on the section size, the counterweight and the engineering, but structural steel cantilevers much further than timber. The Raby Bay truss spanned 18 metres and was fabricated from steel beams and heavy steel angles, working with a 610 UB 101 running the opposite way.
Can structural steel be integrated into a timber-framed home?
Yes. Integrating structural steel into timber-framed residential dwellings is a Network Steel speciality, developed since the business was founded in 1992.
Does steel near the water need special protection?
Yes. Salt air is highly corrosive, so bayside and coastal steel should be hot dip galvanised for long-term protection. The entire Raby Bay truss was galvanised before it left the workshop.
Does Network Steel supply structural steel around Cleveland and the bayside suburbs?
Yes. Network Steel services Cleveland and the Moreton Bay bayside area.
Planning an extension? Speak to our team about your next project - sales@networksteel.com.au | (07) 3821 0424, or get a quote online.
