Housing World-Wide

Sources for the exhibit: International Building Code 2021, Sections 1006.3.4 and Table 1006.3.4(1) (single exits), 1007.1.1 (exit separation), Table 1020.2 (corridor ratings), 1023.2 (stair enclosures), Tables 504.4 and 601; New York City Building Code 2022, Section 1006.3.2 item 7; Seattle Building Code 1006.3.4.7 as summarized in a Los Angeles City Council briefing (September 2025); Approved Document B, March 2024 amendment (second staircases in residential buildings over 18 m, required from 30 September 2026); Musterbauordnung, Sections 14 and 33 (second escape route, 22 m high-rise threshold); EN 13501-2 (R, E, I classes); EU Joint Research Centre on Eurocodes and nationally determined parameters; NFPA Journal, “The Single Exit Stairwell Debate” (2024); Pew Charitable Trusts and Center for Building in North America, “Small, Single-Stairway Apartment Buildings Have Strong Safety Record” (February 2025).

Assumptions: the 80 × 64 ft plate, its four homes, the stair and lift sizes and the 10 ft (3.05 m) floor to floor are illustrative, drawn to one scale in plan and section. Stories under a height limit count floors whose level sits below it. Local amendments vary; the IBC rows are the model code.

This Texan has had several opportunities over the past six years to meet housing architects and developers worldwide. While our focus has always been the United States — the world's number one real estate market — we do have our sights set on upending the feasibility process not just on American shores, but worldwide.

This article will attempt to show major deltas between International Building Code driven planning (what TestFit has built its moat around) and the rest of the world.

Standing On The Shoulders of Giants

We start this journey with Norway, where Autodesk's Spacemaker was born out of a necessity to have buildings conform to absolutely demanding standards — for apartment units these include legally required access to light, reductions for noise, and a smattering of other things that would make an American developer's eyes water.

Dual Aspect Units

This unit type only really occurs in the US when there is an "outside corner." In many European markets, dual-aspect units — units with windows on two exterior walls — are a legal requirement. This single constraint reshapes what a viable building floor plate can look like, and in turn reshapes the entire feasibility calculus.

The world is building housing under wildly different rules. Understanding those rules is the first step to building software that works across them.