Solid oak, one black spine, glass that disappears. The details people notice first.
3¾″ solid oakReal end grain on every tread. No veneer edges.Glass set into every tread½″ glass runs through a slot in each tread. Solid oak caps, no metal on show.Light moves through itOpen risers throw a new shadow every hour.Calm, architectural spacesDesigned with your architect, built to the inch.
Architecture in motion.Engineered in New Jersey, installed across NYC, Long Island and New Jersey. One spine, one contract, one team from drawing to the last tread.
Augmented reality · real size
See it in your home.
Put our stair in your own entry or living room, at true scale, before you spend a dollar.
Open this page on your phone.
Tap View in your room and point the camera at the floor.
Walk around it. Check the run, the headroom and the light.
Choose your starting measurements. The layout is reviewed for your project.
Sizing reference
The dimensions behind the design.
Illustrative planning examples. Final geometry and steel sizing require project review.
Floor-to-floor
Location
Risers
16 × 7½ in
Treads
15
Horizontal run
13 ft 9 in
Approx. opening
11 ft 3 in
Illustrative spine
HSS 12 × 6
Top guard
36 in
Planning values shown for the selected example.
Compare floor heights
Reference table
Floor-to-floor
NJ & Long IslandRisers · treads · run
New York CityRisers · treads · run
Illustrative spineLength · section
Approx. opening
8 ft
13 × 7⅜ in · 12 · 11 ft
14 × 6⅞ in · 13 · 11 ft 11 in
≈ 14 ft · HSS 10 × 6
Full run
9 ft
15 × 7¼ in · 14 · 12 ft 10 in
15 × 7¼ in · 14 · 12 ft 10 in
≈ 16 ft · HSS 12 × 6
≈ 11 ft 9 in
10 ft
16 × 7½ in · 15 · 13 ft 9 in
17 × 7 in · 16 · 14 ft 8 in
≈ 17–18 ft · HSS 12 × 6
≈ 11 ft 3 in / 12 ft
11 ft
18 × 7⅜ in · 17 · 15 ft 7 in
19 × 7 in · 18 · 16 ft 6 in
≈ 19–20 ft · HSS 12 × 6
≈ 11 ft 6 in / 12 ft 2 in
12 ft
20 × 7¼ in · 19 · 17 ft 5 in
20 × 7¼ in · 19 · 17 ft 5 in
≈ 21 ft · HSS 12 × 6
≈ 11 ft 9 in
Reference values, not a final construction specification. In NYC homes, two risers plus one tread must total 24–25½ in (NYC BC §1011.5.2). With 11″ treads that limits each riser to 7¼″. Site measurements, headroom, structural connections and applicable requirements determine the final design.
One engineered steel spine carries every tread. Two connections, no posts, nothing under the flight.
Solid tread
Welded V bracket
Steel spine · mono stringer
Component
Specification
Spine
Closed steel tube, HSS 10×6 or 12×6, sized to the span. Cambered past 18′.
Brackets
¼–⅜″ plate, V-shaped, shop-welded, one per tread
Treads
42″ × 11″ × 3¾″ solid wood, 18″ past the spine each side
Rise × run
7–7½″ × 11″, about 33°. Open riser gap ≤ 3¾″
Base
¾″ plate, 4 anchors into slab or new blocking
Top
¾″ header plate, through-bolted. A moment connection, not a hanger
Loads
40 psf, plus 300 lb on any single tread
Stiffness
L/480 deflection, first frequency 8–10 Hz or more
Spine weight
≈ 700–1,300 lb. Spliced in two when it won't fit inside
Front view
Treads extend equally to both sides.
Someone stepping on the edge of a tread twists the spine. A closed steel tube resists that twist 100 times better than an open I-beam, which is why we never build a mono stringer from one. The gaps between treads are open risers: a look, not the support.
Ends onlyBase plate with four anchors below, a ¾″ header plate through-bolted into the upper floor above.
The top does the workIt carries the weight, the outward thrust and the twist. Where an old floor can't, we add a header or post.
Sized to the span10″ tube up to about 15′ of spine, 12″ beyond, cambered past 18′. A landing past about 22′.
Shop-welded, site-boltedBrackets are welded and checked in our shop. On site everything bolts together.
Brownstone deliveryA one-piece spine for a 10′ parlor floor is about 17′ long. If it won't turn the stoop or hall, we build it in two pieces with a hidden bolted splice.
Old joistsEach end pushes 2–4 kips into the floor. Century-old 3×10 joists usually need a new header with posts or a steel channel on the party wall.
Co-op & condoWe prepare the alteration package, insurance certificates and work schedule your board asks for. Townhouses →
Installed in 2–3 days.
From first call to install usually takes 3–6 months.confirm Full timeline →
Day 1Spine & anchorsHeader plate bolted up, spine lifted and set, base plate anchored, everything leveled.
Day 2Treads & handrailTreads fixed from below onto the brackets. Wall handrail and rod or cable guard.
Day 3Lighting & touch-upsLED drivers connected, powder coat touched up, site cleaned.
+2–4 weeksGlassMeasured once the spine is set, installed in half a day.
Removing an old stair adds 1–3 days.confirm
What it costs.
Installed prices: design, PE engineering, fabrication, powder coat, delivery and installation. Permit fees and co-op deposits are billed at cost.confirm
Still unsure? Send a photo of your stairwell and we'll tell you what fits.
What is a straight mono stringer stair?
A straight flight carried by one central steel spine, with every tread extending equally to both sides. It looks like it floats, but the spine under the middle carries all the load.
How long is a straight mono stringer stair?
About 14′ of floor for a 10′ floor-to-floor height: 15 treads at 11″ each. An 8′ loft stair runs about 11′, a 12′ height about 17½′. Use "Will it fit your space?" above for your height.
Does it need a post in the middle?
No. It is held only at the floor and at the upper floor. Past about 22′ of spine, or 12′ of rise in NYC, we add a landing instead.
Can it go against a wall?
Yes, and most do. The guard goes on the open side and a handrail on the wall. The treads stop about 1″ short of the wall.
Will it bounce?
Not when it is sized right. We use a closed steel tube and design for L/480 deflection and a natural frequency of 8–10 Hz or more.
Can you get it into a brownstone or up an elevator?
Yes. If the one-piece spine won't fit, we make it in two pieces with a hidden bolted splice and assemble it inside.
How much does it cost?
From $28k installed in New Jersey and $34k in New York City for a 9–10′ flight with oak treads and a cable or rod guard. With frameless glass, $36–48k in NJ and $42–58k in NYC.
Get a price in 3 business daysconfirm
Start your straight mono stringer
Your choices from above are already filled in. Add a photo of each end of the stair.
Your design
White oak · frameless glass · matte black spine · 10′ · along a wall · New Jersey
Straight mono stringer →
Frameless glass →
Solid white oak →
Light under every tread →
