What to sort out before building a steel shed in Brisbane

Brisbane is hard on steel sheds. Summer storms test the frame, and anywhere near the bay, salt works on the cladding year round. Your address decides the wind rating and how much salt the sheeting will face. Size and placement are your call, and getting them right on paper costs far less than fixing them once the slab is down.

The questions below apply to a 3 x 3 m garden shed as much as a double-bay workshop for the boat.

What will the shed really be used for?

Measure the biggest thing going in, then add room to walk around it and open its doors. Height is what catches people out. A caravan with a roof-mounted air conditioner can stand close to 3 m, so a 2.4 m roller door won't clear it, and you don't want to learn that with the van in the driveway.

A workshop needs bench space and clearance for long lengths of timber, while a home gym needs windows for airflow. Whatever the use, go a size bigger than you think you need, because adding a bay later means a second slab pour and possibly a fresh approval.

What wind rating does your block need?

Brisbane sits in wind region B under AS/NZS 1170.2, the Australian wind loading standard. That is only the starting point. Terrain and exposure move the design wind speed up or down for each address.

A shed on open acreage at Mount Cotton or high in The Gap needs a higher rating than the same shed tucked between houses on a flat street in Carina, and blocks facing open water cop more wind again.

Check that the quote and the engineering both list a wind classification for your street address. Then look hard at the doors. When a large roller door blows in during a storm, air pressure inside the shed jumps and pushes up on the roof sheets from underneath, which is a common way for a roof to lift on a shed whose frame was built properly. Ask for doors that carry the same wind rating as the frame.

How close are you to salt air?

Salt spray reaches further inland than most people expect. On the bayside, in Wynnum or out at Redcliffe, ask for a coating made for marine conditions and read the coating warranty for a minimum distance from the coast, since some warranties cut cover close to salt water. Check the screws as well: a fixing made from a different metal to the cladding corrodes where the two touch.

Hose the walls under the eaves every few months. Rain never reaches those spots, so salt builds up there first.

Where on the block will it go?

Walk the block after a heavy storm before you pick a spot. Wherever water is still lying an hour later is a bad place for a slab.

Check boundary setbacks and where the sewer and stormwater lines run. In Brisbane, building over or near a sewer main needs approval from Urban Utilities, which adds a step and some waiting.

Then pull Brisbane City Council's free FloodWise Property Report. It shows whether your block sits in a flood overlay, and that can change where the shed goes and how high the slab sits. Side access gets forgotten until delivery day. A concrete truck and a kit delivery both need a clear way in, so measure the gap beside the house before you commit to a spot down the back.

Which colour and roof style suit your house?

A shed close to the house reads as part of it, so match the roof pitch or pick a colour from the existing exterior. A gable roof suits most Queenslanders. A skillion sits neatly beside a modern build. Go lighter on the roof than you think you need, because under a dark roof a steel shed in January is too hot to work in by early afternoon.

Who handles council approval, and how much of the build do you want done for you?

Size and siting decide whether a shed needs approval, and in Brisbane many do. In Queensland the building approval comes from a private building certifier. Council steps in where planning rules apply, such as a flood overlay or a shed built close to a boundary.

A kit is the cheaper route. You save on labour, but the paperwork and the build become yours, bracing and fixings included. If you've never stood a steel frame up, I'd pay for the full build.

Fair Dinkum Builds is one of the shed builders across Brisbane that will lodge the approval and do the install as one job. Get a second quote on the same spec anyway so you are comparing like with like, and before any deposit changes hands, find out who lodges the approval and whose name goes on it.

When should the slab go in?

Book it as soon as approval comes through. The slab has to be poured and cured before the kit arrives, and your builder will tell you how long to wait before the frame goes up.

Pour it to the shed's engineering. Footing sizes and hold-down bolt positions come from the frame and its wind rating, so a slab poured early to a generic spec can put the bolts in the wrong place. A lot of Brisbane sits on reactive clay that swells when wet and shrinks when dry, and a soil test shows whether you need thicker edge beams or deeper footings.

If you want power in the shed, lay conduit before the pour. Cutting into cured concrete later is slow and messy.

How long will the whole job take?

The stages run in order: site visit and quote, engineering, approval, slab, delivery, build. Approval varies the most, and it is the one stage you can't hurry. Summer storms also push back slab pours. If you want the shed finished by Christmas, start the paperwork in winter.

What services will the shed need?

In Queensland, wiring has to be done by a licensed electrician. Get one in early to place lights and power points around your benches. If you're adding a sink or plumbing in a rainwater tank, bring a plumber in at the same time so the trenches only get dug once.

Heat is the problem you will notice most often. Insulation under the roof sheets cuts it and stops condensation dripping on your tools, and whirlybirds or high wall vents let the hot air out. For daylight, two translucent roof sheets are usually enough that you won't need a light on during the day.

What does the warranty cover?

Steel shed warranties often split the frame and the cladding coating into separate parts, each with its own conditions. Common ones are washing the walls in coastal areas and keeping soil and garden beds clear of the base.

Keep the paperwork and a few photos of the finished slab together. You'll need them for a claim, and a buyer may ask for them when you sell.