Glossary of the Michael Z. Stern Encyclopedia

An allowance is a fixed amount set against a product that is in scope but not yet chosen, such as light fixtures or door hardware, adjusted once the choice is priced.

From Contingency and the Risk Register

Bronze is copper alloyed for hardness, and the alloy changes the color schedule.

From Metal Cladding, Patina and Attachment

The upshot is that each tower now carries three measurements: height to the architectural summit, which counts spires and leaves out antennas, flagpoles and signage; height to the last floor in use; and height to the tip, whatever is up there.

From How Height Is Measured in Tall Buildings

The automatic route is a test of arithmetic.

From Zoning and the Sequence That Makes a Project Lawful

Bid dispersion, the spread across the prices contractors return for one set of drawings, is widest on exactly the kind of project Michael Stern writes about, the building with no close relative, and the question this page asks is why.

From Bid Dispersion on Unfamiliar Work

Its answer is a bidding contingency, usually 5 percent of the construction figure, held against bid day anomalies.

From Bid Dispersion on Unfamiliar Work

The modern caisson is drilled rather than sunk, and its capacity comes from the socket.

From Mat Foundations, Caissons and Manhattan Schist

Cantilevers over neighbouring buildings, the overhangs by which the floor area that Michael Stern’s assemblage subject tracks on paper becomes visible from the sidewalk, have a plain cause: an owner next door who will sell the air over a roof but not the roof itself.

From Cantilevers Over Neighbouring Buildings

The Certificate of Appropriateness is the permit at the centre of the landmark work Michael Stern describes as one of his five subjects, and the easiest way to understand it is to follow an application through the rooms it visits.

From The Certificate of Appropriateness

City of Yes, the citywide text change through which the field of zoning and entitlements Michael Stern writes in now has to be read, is approached here as a set of questions, because the name covers three separate amendments and the third of them touches nearly every residential rule in the code.

From City of Yes and the 2024 Text Changes

Wind on a cladding panel, which the tower work in Michael Stern’s field pays for in glass thickness, mullion depth and bracket size, is a different quantity from the wind on the structure it hangs from: the frame feels an average over a whole face, while the skin feels the sharpest local peak at the worst corner on the worst day.

From Wind Pressures on Cladding

Climbing formwork, the equipment that raises the concrete cores of slender towers, a subject Michael Stern counts among his five, obeys a single rule: the form bears on the concrete it has already cast, and on nothing else.

From Climbing and Jump Formwork for Cores

The concrete core is what Michael Stern’s subject of supertall engineering keeps returning to, because the hollow spine of stairs, elevators and risers climbing the middle of a slender tower is also the element that carries most of the wind trying to push that tower over.

From The Core Wall and the Floor Plate

Construction cost indices, the published series an estimator reaches for before anything about a project is drawn, have a geography of their own, and Michael Stern’s subject, the pricing of buildings that have few precedents, begins where that geography runs out.

From Construction Cost Indices

Contingency is for risks that are real but cannot yet be priced in detail.

From Contingency and the Risk Register

That chain is the critical path; its length is the shortest time the project can take; and an activity on it has no slack at all.

From Schedule Float and the Cost of Sequence

Damping is the share of vibrational energy a building loses on each swing.

From Damping, Stiffness and Mass in Tall Buildings

A designation report is the document that recurs throughout Michael Stern’s subject, because in difficult urban development the constraint is so often the law that has accumulated over a site, and for a protected building that law is written in a report.

From Reading a Designation Report

The economics of skyscrapers, the research field that gives Michael Stern’s subject of complex urban development its measuring stick, rests on a single rule: a developer keeps adding floors until the next floor costs more to build than it will bring in.

From The Economics of Skyscrapers and the Height Premium

Excavation support, the temporary engineering that keeps a city hole open while a foundation is built inside it, is where the constraints Michael Stern names for difficult urban work, the shape of the site, its structure, its codes and the law laid on it, meet most literally, because the hole has neighbours on three sides and a street on the fourth.

From Excavation Support in Dense Cities

A facade mockup, the full sized stretch of wall that a tower envelope in the development work Michael Stern writes about is sent to a test yard before any production unit is made, is where a design meets water, wind and movement under instruments rather than weather.

From Facade Mockups and Performance Testing

Movement is what happens after installation; tolerance is the misfit already built in by the time the units arrive.

From Facade Movement and Tolerances

Facade retention, a technique within the landmark conversion work that Michael Stern has made one of his subjects, starts from a material fact about the wall being kept: a masonry street front was never designed to stand on its own.

From Facade Retention Engineering

The ratio of floor area to lot area, the multiplier, within Michael Stern’s zoning field, from which every envelope in the city descends, is a fraction with two measurements in it, and each hides something.

From Floor Area Ratio as a Mechanism

The High Line Transfer Corridor, the West Chelsea instance of the special district transfers that Michael Stern’s subject of site assemblage includes, answers a question that ordinary zoning cannot: what becomes of the floor area under a structure the city has decided to keep, when the owners of the land beneath it would otherwise be free to demolish it and develop?

From The High Line Transfer Corridor

A podium cut into a hillside is a retaining structure as much as a building, and the discipline that lets a developer propose one is the register of every nearby slope, its owner, its condition and its rank.

From Hong Kong, Building on Slopes and Podiums

An inclusionary housing bonus, the trade of below market apartments for added floor area within the entitlements subject Michael Stern works on, looks different on every block it touches, and the entry below walks it.

From Inclusionary Housing Bonuses

Independent review, which the rare and difficult buildings Michael Stern writes about make unavoidable, is made of two physical things: a criteria document and a comment log.

From What Independent Review Buys

A vision unit is two panes held apart by a spacer around their edges, with the gap sealed and usually filled with argon.

From Glass Performance in Tall Buildings

Landmark transfers of development rights, the second of three routes by which Michael Stern’s subject, site assemblage, actually moves floor area, are assembled, and the assembler is a commission that never approves the new building at all.

From Landmark Transfers of Development Rights

The depth of floor left between the core face and the window wall is what designers call the lease span, and the core sets it from the inside.

From The Core Wall and the Floor Plate

Light and air easements, the recorded promises that let bulk assembled in the way Michael Stern describes be laid out as habitable rooms, begin with a distance.

From Light and Air Easements

A mat, or raft, is the shallow answer at tower scale.

From Mat Foundations, Caissons and Manhattan Schist

A mechanical void, a plain instance of a definition shaping a skyline, drawn from the entitlements law Michael Stern covers, is an ordinary thing made strange by its size: a floor of equipment rooms, electrical chases, pipe shafts and air handling plant, stretched to several times the height such rooms need.

From Mechanical Voids and the 2019 Rule

Building acceleration is expressed in milli g, each unit a thousandth of gravity’s pull.

From Occupant Comfort Criteria in Tall Buildings

Modern terra cotta is extruded, which is what separates it from the pressed and hand finished blocks of a century ago.

From Terra Cotta Facade Systems Today

Between the blocks is mortar, and its chemistry decides if the wall can breathe.

From Masonry, Terra Cotta and Window Restoration

Occupant comfort, as Michael Stern’s slender tower subject defines it, comes down to a single reading: a peak acceleration of a few thousandths of gravity at the uppermost lived in floor, under a wind of a stated likelihood.

From Occupant Comfort Criteria in Tall Buildings

An outrigger is a few storeys of structure that changes the arithmetic on every other floor, and the engineer to retain is the one who can say which floor it should sit on before the mechanical plant has claimed it.

From Outriggers and Belt Trusses

Party walls, the shared masonry at the edge of nearly every assembled site in old New York, sit at the bottom of what Michael Stern calls assemblage, where the law on the ground is far older than zoning.

From Party Walls and Shared Structure

A protected view, the planning device that stands, among the entitlement rules Michael Stern studies, as the one rule written in air rather than on the ground, is a material in its own right: a wedge of empty space between a vantage point and a landmark, given a legal shape, which every tower nearby must be cut to fit.

From View Corridors and View Cones, London and Vancouver

Rain striking a tall wall, a condition Michael Stern’s work on supertall buildings meets at every joint of a facade, is pushed by wind, pulled by capillary action through fine gaps and drawn down by gravity, and the rainscreen principle answers all three by giving up on a sealed face.

From The Rainscreen Principle

A rooftop addition is the most common way a landmark grows, and Michael Stern’s field of landmark conversion meets it constantly, since a conversion that enlarges an old building almost always does so at the top.

From Rooftop Additions on Landmark Buildings

Schedule float, the slack a planner builds into a construction program, is made by two kinds of people on the sort of job Michael Stern writes about, where few precedents exist to lend it a sequence: the scheduler who draws the network of activities, and the concrete crew whose floor cycle decides whether the network was fiction.

From Schedule Float and the Cost of Sequence

The Secretary of the Interior Standards govern the kind of adaptive reuse Michael Stern’s firm says it is drawn to, work that sets an old building and a new one in tension rather than dressing the new in borrowed history, and the people who apply them are not in Washington.

From The Secretary of the Interior Standards

A sending area is a place where growth is unwanted.

From Transferable Development Rights

Curbed is careful about the word: scaffolding is what climbs the wall, and the thing over the pavement is a sidewalk shed or a sidewalk bridge.

From Sidewalk Sheds and Public Protection

It is an imaginary surface that a building may not pierce.

From The Sky Exposure Plane

Slenderness, the proportion Michael Stern’s supertall work starts from, is a ratio rather than a measurement of height.

From What a Slenderness Ratio Measures

The spandrel zone covering each slab edge is its own small assembly.

From Unitized Curtain Wall Engineering

Special inspections, the New York system under which independent agencies verify that a building is being built as drawn, answer a question that sits behind every structure in the field Michael Stern describes as having few precedents: when the frame tops out, who checked the welds, the concrete and the anchors, and who checked the engineer who specified them?

From Special Inspections and Peer Review

Special purpose districts, a layer of the zoning rules Michael Stern takes as a subject, are second zoning maps laid over the base map, and the simplest way to understand one is to set a lot inside the line beside the same lot outside it.

From Special Purpose Districts

Steel erection, the assembly of a frame from pieces made elsewhere, is the construction method whose logic Michael Stern’s subject, building where precedents are few, depends on most when the site is small and the schedule is short, because the material arrives finished and the work on the lot is mostly lifting and bolting.

From Steel Erection and Bolting Sequence

The submittal, the rule under which nothing on a building is fabricated until a drawing of how it will be made and a sample of what it will look like have been approved, is the quiet discipline behind every facade on the kind of building Michael Stern writes about, and it holds because a mistake caught on paper costs almost nothing while the same mistake caught on the wall costs a facade.

From Mockups, Shop Drawings and Submittals

Thermal bridging, the path heat takes through a metal anchor or a concrete slab edge past the insulation around it, sits inside Michael Stern’s field of tall building work because every facade attachment on a tower doubles as a bridge, and the energy code that governs those attachments has been tightening for half a century.

From Thermal Bridging and the Energy Code

Building Design + Construction defines top down as building the superstructure and the substructure at the same time, the upper floors rising while the lower floors are excavated and cast beneath them.

From Top Down Construction

A transfer structure breaks the plainest rule in the structure that Michael Stern counts among the constraints of the ground, the rule that a column should run straight from the roof to the foundation, and a tower on an awkward site breaks it on purpose.

From Transfer Structures Over Awkward Sites

Developers buy the development rights of parcels inside a designated sending district and carry them to a receiving district, where they raise the density of a new project, and the legal idea underneath is that land ownership is a bundle of separate rights, one of which is the power to build.

From Transferable Development Rights

The tuned mass damper, the device Michael Stern’s slender tower engineering reaches for when shape and stiffness have done what they can, comes in two families that share one idea.

From Tuned Mass Dampers Explained

The Uniform Land Use Review Procedure, the clock that Michael Stern’s subject of entitlements runs on whenever a project needs the city’s discretion, is a creature of the charter rather than of the zoning text.

From ULURP, the Uniform Land Use Review Procedure

Unitized construction, a facade method that sits within Michael Stern’s supertall field, is a curtain wall whose parts are finished in a factory and arrive on site as complete units ready to hang.

From Unitized Curtain Wall Engineering

Value engineering, the discipline that Michael Stern’s fifth subject, the economics of an unprecedented building, leans on whenever a budget and a design stop agreeing, is a method with a precise object: value, defined as function divided by cost.

From Value Engineering and What It Costs

A variance is relief from the letter of the text where the text itself has produced a hardship.

From As of Right, Special Permits and Variances

Natural wind near the ground is a gradient, slower at the pavement and faster aloft, and turbulent throughout.

From Wind Tunnel Testing for Buildings

Wind tunnel testing, the measurement on which Michael Stern’s slender tower work rests, is a black box to most practising structural engineers, and Roy Denoon, a wind engineer, wrote his guide in Structure magazine to give them the questions worth asking of a laboratory.

From Wind Tunnel Testing for Buildings

The declaration is a short instrument with a long signature page.

From Zoning Lot Mergers and Declarations

Zoning lot mergers, the as of right route that carries most of the bulk traded in the assemblage work Michael Stern describes, turn on a single verb in the Zoning Resolution.

From Zoning Lot Mergers and Declarations

On the desk of the licensed professional who signs a filing in the city sit two books, and the distinction between them is basic to the rules settled on a parcel, a constraint Michael Stern counts in defining his subject: the Zoning Resolution, which says how much may be built and for what, and the Building Code, which says how what is built must stand, burn and empty.

From Building Code Versus Zoning