Hot-dip galvanised steel stringers from 1 step through to 17 steps, supplied as a pair — 2 pieces, so one product covers both sides of the stair.

Three mounting types, all available across the full 1–17 step range: Concrete-In, Bolt-On Concrete and Landing-To-Landing.

• Concrete-In — the base of the stringer is set into a concrete footing as it is poured. For new work where the footing is going in at the same time. Generally the strongest connection.
• Bolt-On Concrete — bolts down onto an existing slab, path or footing. For adding stairs to concrete that is already there.
• Landing-To-Landing — fixes between two finished levels with no ground footing at all: a deck down to a landing, an upper deck to a lower one, or between two platforms.

The question to answer first is simply what the bottom of the stair lands on — new concrete, existing concrete, or another structure.

Because a stair needs two. Ordering a 6-step stringer gives you both sides in the one purchase, which removes the most common ordering error on this product.

For a wide stair you may need a third stringer in the middle — in that case order a second pair and use the spare, or talk to us.

Count the treads, not the total rise. A stringer described as 6 step carries six treads.

Measure the vertical height from the finished lower surface to the finished upper surface, then work out how many risers divide into that at a consistent, comfortable height. The number of treads is usually one less than the number of risers, depending on how the top step meets the deck.

Riser heights and tread depths for stairs are regulated, so confirm your dimensions against the applicable building requirements before ordering.

Do not split the difference by making some risers taller than others. Uneven risers are both a trip hazard and generally non-compliant.

The usual fix is to adjust the finished level at the bottom — the thickness of the landing slab or paving — so the rise divides evenly. Work that out before the concrete goes in rather than after.

Send us your measured rise and we will work through the options with you.

No, the stringers are supplied on their own. We stock the treads separately so you can choose the timber and the width.

Our solid Merbau step treads come in 240, 250, 290 and 300mm widths, in 35, 42, 45 and 50mm thicknesses. 240mm and 250mm suit most domestic stairs; 290mm and 300mm give a deeper, more generous tread for entry steps and feature stairs.

Use cup head bolts with nuts. This is the single most important thing you can do to avoid cracking a tread.

The cup head sits flush on the walking surface with nothing to catch on, and the bolt lets the timber sit against the steel without being drawn hard onto it.

Coach screws driven up through the stringer into the underside of the tread are the most common cause of cracked treads.

They pull the timber down hard onto the steel, they are easy to over-tighten, and the load concentrates in a small area of a dense board that wants to move seasonally. Merbau in particular will not tolerate it for long.

Use cup head bolts and nuts, and tighten only as much as needed to secure the tread — no further.

Yes — seal all sides before installation, including the ends and the underside.

This is the most commonly skipped step, because those faces will never be seen. But an unsealed underside or end grain takes up and releases moisture at a different rate to the sealed top face, and that imbalance is what causes cupping, movement and splitting later. Sealing every face lets the board move evenly.

• Allow for movement between timber and steel. They expand and contract at different rates, so the fixing detail needs to accommodate that rather than lock the tread rigidly in place.
• Support longer treads properly. A wide tread spanning between stringers will flex — add intermediate support where needed.
• Keep water moving. Water sitting on or under a tread is what shortens its life.
• Pre-drill dense hardwood near ends and edges to avoid splitting.

Hot dip galvanised cup head bolts and nuts, with washers under the nuts. We stock M10 and M12 in lengths from 75mm to 200mm and beyond — pick the length from the tread thickness plus the stringer plus enough thread for the nut.

On a coastal site, step up to stainless. The bolt heads sit on the walking surface, so they are the part that shows and the part that weathers.

Yes — the stringers, the Merbau treads, the bolts and washers, plus handrails, balustrade timber and post supports if the stair needs them.

Send us your measured rise, what the bottom of the stair lands on, and the tread width you want. We will confirm the step count, the mounting type and the fixings.

Browse the full Decking Wood QLD range of stair stringers, step treads, handrails, decking and hardware.