Addressing Middle Housing Through Building Codes

Demand for accessible and cost-effective housing options continues to grow across the United States. One housing type drawing increasing attention is small, multifamily buildings that fall outside the scope of the International Residential Code® (IRC), often referred to as “middle housing.”

This category includes duplexes, triplexes, fourplexes and small apartment buildings that provide diverse and relatively affordable housing options for households across a wide range of incomes. 

Multifamily Buildings in the International Codes

The International Codes® (I–Codes®) already include model provisions that span the full spectrum of multifamily building types, supporting developers, designers and jurisdictions in delivering safe, affordable and efficient housing. These provisions are intentionally risk based, recognizing that different building types present different life safety considerations and therefore warrant different regulatory approaches. 

The International Building Code® (IBC), for example, clearly differentiates between larger, multistory apartment buildings and smaller, low-rise multifamily buildings. A two-story, 16-unit apartment building in which each dwelling unit exits directly to the exterior is regulated differently than a five-story, 40-unit apartment building with a shared interior means of egress.

This differentiation reflects meaningful differences in fire, egress and life safety risk, and ensures that the IBC does not apply a one–size–fits–all approach to the varied construction types it addresses. 

Get Involved 

Middle housing remains an active and evolving topic in the code development process. For instance, the IBC – Means of Egress Code Development Committee has approved a proposal relevant to middle housing that would permit single exit up to four stories (see E24-24). That proposal and others will be debated during the I-Codes Public Comment Hearings beginning April 19th in Hartford, CT. Click here for additional information on those proceedings and how to participate.   

In addition, the Building Code Action Committee (BCAC) has launched a working group focused on high density multifamily housing. This effort provides another near-term opportunity for stakeholders to help shape how the I–Codes address middle housing. Interested parties can sign up through the ICC Committee Application page by selecting “Interested Party Lists” and requesting to be added to the BCAC – Residential – High Density Multifamily Housing list. Getting engaged takes less than a minute and helps ensure a broad range of perspectives inform this important work. 

To support the BCAC working group, as well as practitioners and jurisdictions more broadly, ICC is also developing a new consolidated reference publication designed to make applicable provisions for middle housing easier to navigate. This resource will compile relevant IBC provisions for high density multifamily housing (Occupancy Groups R2 and R3) that fall outside the scope of the IRC. The publication is intended to improve usability and clarity while reinforcing the I–Codes’ longstanding commitment to safety, affordability and regulatory flexibility. It is scheduled for release later this year. 

Learn more about the I-Codes and the code development process, here.