TwiniwT · MAD

The built stair at dusk with four students on it, one balancing against the handrail, a bench worked into the pocket on each side and lit from beneath — Design-build bench · Cal Poly San Luis Obispo · 2019
TwiniwT

Two mirrored benches built into the leftover pockets either side of a campus stair, on the idea that a bench is how architecture tells the public a place is theirs.

A stair from the Engineering West building down to Dexter Lawn went in during 2005 and left a wedge of unfinished ground to either side of it. Both sat unused from then on. The benches fill them, one to each side, mirrored: the name reads the same in both directions because the pair does.

Studio: Cave Studio, Cal Poly
Site: Engineering West stair to Dexter Lawn
Program: Twin benches, one each side
Capacity: 1–2 people per bench
Structure: Zinc-plated steel angle
Surface: CALI Bamboo composite decking

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A student reclining on the built bench with their feet up on the deck, the rope net lit from below behind them and the planted strip running down the raking edge of the stair — The finished seat, and the lit net

Materials

CALI Bamboo composite decking over a steel angle frame, fixed with 18-8 stainless screws and nylon-insert locknuts. The decking is the board the studio had already used on its earlier benches, which holds up outdoors with no finish schedule for anyone to keep up.

Fabrication

Every steel piece was drawn as a flat blank with its hole pattern and bend angles before anything was cut. The latch bracket comes off the sheet as one 17 in blank with 3/8 in and 3/16 in holes, folded at 20 degrees. Three 1/8 in fillets fix the keeper to the frame. Each seat lifts on a zinc plated piano hinge and padlocks shut, so the space behind the bench is accessible for maintenance.

Five students on the finished bench in the pocket between the concrete walls, three seated on the deck and two standing either side — As built, in use

A man lying back along the finished bench in full sun, one hand on his cap and his shoes off beside him, the accessible route sign on the concrete pier to the right — As built, in use

Documentation

Construction document / assembly model

Interactive · assembly sequence

1.7 MB · runs in your browser

Bench: infill, steel, lumber, deck, guard and fixings Existing stair, wall and ground: section through it to see the fit

The set

01 / 04

Paired perspective of one pocket, the concrete either side of the stair shown first empty and then with the bench worked in, the seat deck stepping up to the netted back between the two walls — TT-V1_1 · perspective, empty pocket and built bench

Plan of both benches either side of the stair, 23 ft 5 1/4 in overall with 10 ft 10 in of stair between them, each seat pocket about 46 in wide, section A cutting through the right-hand bench — TT-V1_2 · plan

Front elevation of the pair looking at the stair, the concrete walls 10 ft 2 in tall inside a 13 ft 6 in overall dimension, seat backs at 36 in and the deck at about 33 in above each pocket floor — TT-V1_3 · front elevation

Section through one bench with the seat swung up on its piano hinge to 110 degrees, callouts naming the CALI Bamboo composite decking, the zinc plated steel angle and the pull release latch, the deck detail drawn separately above — TT-V1_4 · section A, seat open

The leftover space

Neither pocket was meant to be used. They are what the stair left behind when it pulled away from the wall, and for fourteen years nobody had a reason to stand in either. Every campus has spaces like this. Nothing is wrong with them, they are only left over, and that is enough to make people stop seeing them. We saw them. The rest was working out what would make somebody stop and sit. The pockets already had the good part: concrete on two sides, open sky above, the stair structure going by at your shoulder. Not quite outside, not quite indoors. The benches only make it somewhere you can stay.

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