Shapiko

How to quote spiral and metal stairs online

A stair isn't a part number — it's a shape (spiral, straight, or L with a landing), a height to clear, and options that change the parts count and whether it meets code at that size. Here's what buyers need to pick, how height drives tread count and rotation, the general code points worth keeping in front of them, how stair makers usually price this, and how a configurator turns the inputs straight into a quote.

What a buyer needs to decide before you can quote

• Stair type. Spiral (a center pole, treads winding around it), straight, or L-shaped with a landing. A spiral is bought mostly by diameter and height; a straight or L run by width, height, and run length.
• Floor-to-floor height. The actual vertical rise, top finished floor to bottom finished floor, not a guess. Every other dimension builds from this one number.
• Diameter (spiral) or width (straight/L). Too small a diameter at too great a height makes for a steep, narrow climb.
• Tread type. Plate steel (bare, checker plate, or grip-coated), grating, or a surface built for wood or tile infill — as much a look choice as a cost one.
• Open or closed risers. Closed feels more conventional and blocks the view through the stair; open shows through and usually saves weight and material.
• Handrail style and sides. Picket, cable, or bar infill, and whether the rail runs one side, both sides, or — on a spiral — just the outer edge.
• Landing guard rail. Length and style at the top landing, matched to the handrail so the two don't read as two different products.
• Finish. Powder coat color, galvanized, or raw for the buyer's own painter.

Height and diameter (or width) are the two numbers that actually size the job — the rest is options layered on top.

How tread count and rotation follow from height

Once you have the floor-to-floor height, tread count isn't really a choice — it falls out of the riser height you build to. Divide the rise by your target riser height and round to a whole number of risers; that number, minus one, is roughly the tread count. A taller rise at the same riser height simply adds treads, which is why two stairs with the same diameter can have noticeably different tread counts once the height changes.

On a spiral, tread count also sets the rotation: each tread occupies a fixed angle around the center pole, so more treads means more degrees of turn before the stair reaches the top. A wider diameter gives a deeper tread at the same angle, letting you use a taller riser and fewer treads; a narrower diameter needs more, shallower treads. Reworking this by hand for every quote is tedious — the first thing worth automating.

Straight and L-shaped stairs follow the same riser-height math for tread count, but width doesn't change rotation — it changes stringer and handrail length, and on an L, the landing size and where the run turns.

General code points worth keeping in front of buyers

Codes vary by jurisdiction and get amended locally, and spiral stairs are often treated differently from straight stairs under the same code. None of this is legal advice — point buyers to their local building department for the number that actually applies.

• Riser height. Most residential codes cap it in roughly the 7–8 inch range; spiral stairs are sometimes allowed a taller maximum riser than a straight stair of the same use.
• Tread depth. A minimum applies, measured at the walking line; spiral stairs are typically measured closer to the tread's narrow end, which is why a spiral's minimum usable tread looks smaller.
• Headroom. A minimum clear headroom above the nosing line, commonly discussed around 6 ft 6 in to 6 ft 8 in depending on stair type and use.
• Guard height. A minimum at open sides and landings, commonly discussed in the mid-30s to low-40s of inches, with handrail height set lower than guard height.

A buyer who picks a height and diameter too tight for these limits isn't picking an option, they're picking a stair you can't legally build — worth catching during configuration, not on a shop drawing review.

How stair makers usually price this

Method	How it works	Works best for
By diameter and height	Priced on spiral diameter and floor-to-floor height (or run length and height for straight/L), since those two numbers mostly set tread count and material.	Standard diameters or widths, a repeatable build — fast to quote, easy to publish as a table.
Per tread	A base cost per tread (material plus welding time), times the tread count the height works out to, plus a center pole or stringer charge.	Shops where custom heights are common enough that a flat size table misses too many jobs.
Base price + options	A base at a reference size, then line items for tread surface, closed risers, handrail, landing rail, and finish.	Real option spread — maps cleanly onto a website since it mirrors how the job gets built internally.

In practice most shops blend the first two — diameter or width sets a base, height-driven tread count adjusts it — then add options on top.

Common pricing mistakes

• Quoting from diameter alone. A 5 ft diameter spiral at 9 ft of rise and the same diameter at 14 ft of rise are different jobs. A single "starting at" price trains buyers to expect the shortest rise.
• Letting a size fail code and finding out later. Checking riser height, tread depth, or headroom only at the shop-drawing stage means redoing a quote you'd already spent time on.
• No price online at all. "Call for a custom quote" loses buyers comparing a few shops to whoever gives a number first.
• A form that goes silent. An intake form with no price feedback reads the same as no price — a lead, but a cold one.
• Treating handrail and landing rail as an afterthought. On a spiral especially, the rail and guard are a real share of the cost — pricing them as a late "call us" line loses trust once the buyer has anchored on the stair price alone.
• Publishing a full cost breakdown. Tread, pole, and welding hours shown separately invites haggling. Buyers want a total and what's included.

How a configurator handles this

A 3D configurator built from your own price list collects the inputs in order — stair type, floor-to-floor height, diameter or width, tread type, open or closed risers, handrail style and sides, landing rail, finish — and prices from your rules as each one is picked. Tread count and, on a spiral, rotation are worked out from the height and diameter entered, and riser height, tread depth, and headroom are checked against general code limits as they configure, so a buyer can't land on a size you can't build to code. They see the stair update in 3D at their exact size, and the quote request that reaches you arrives with the full configuration and a parts list filled in — not a one-line email asking "how much for a spiral staircase."

A spiral stair sample shows this end to end: diameter, height, tread surface, risers, handrail, and landing rail as real options, with tread count and price updating live. It's a fictional company with illustrative prices — yours runs on your real price list and rules.

See the stair configurator Built from your price list, usually within one business day. Free working draft.