Incremental population density improvement via missing middle housing under density-based and form-based zoning ordinances

• Date: 07 August 2023
• Pages: 87-105
• DOI: https://doi.org/10.1108/IJHMA-06-2023-0074
• Published date: 07 August 2023
• Subject Matter: Property management & built environment,Real estate & property,Housing markets
• Author: Xingrui Zhang,Eunhwa Yang,Liming Huang,Yunpeng Wang

Incremental population density

improvement via missing middle

housing under density-based and

form-based zoning ordinances

Xingrui Zhang

CSCEC Infrastructure Corp, Beijing, China

Eunhwa Yang

School of Building Construction, Georgia Institute of Technology, Atlanta,

Georgia, USA

Liming Huang

School of Architecture, Royal College of Art, London, UK, and

Yunpeng Wang

2nd Engineering Bureau, China State Construction Engineering Corporation Ltd,

Beijing, China

Abstract

Purpose –The purpose of the study is to observe the feasibility of missingm iddlehousing’s (MMH) realization

under density-based zoning, form-based zoning and a combination of both while simultaneously providing

affordable housing, improvingquality of life and making eff‌icient use of land.

Design/methodology/approach –This study takes a theoristapproach and designs three hypothetical

cottage court projects that comply with all relevant off‌icial local zoning ordinances to showcase design

feasibility, followed by an analytical component in the form of a f‌inancial model constructed using off‌icial

local economicand demographic conditions.

Findings –MMH, and in particular cottage clusters, can be implemented under rigorous density-based,

form-based and hybrid (density-based þform-based) zoning ordinances and provide affordable housing

(Atlanta, GA), improve quality of life (Blackpool, UK) and make eff‌icient use of land (Jinan, China). All

hypotheticalprojects are f‌inancially feasible under reasonableconditions.

Originality/value –To the best of the author’s knowledge, this paper is the f‌irst in the body of

knowledge to discuss how the MMH can be integrated into urban density-based zon ing rather than

converting density-based zoning intoform-based so that the MMH can f‌it. The paper also takes a cross-

national perspective and discusses the feasibility of MMH in the resolution of housing issues in the

USA, China and the UK. The study also concludes that the issue of housing unaffordability in the UK

wascausedbyhighconstructioncostrelativetomedianincome.

Keywords Missing middle housing, Population density, Zoning, USA, UK, China

Paper type Research paper

Data availability: The f‌iles used for f‌inancial modeling and land cost calculations will be provided

upon reasonable request with the f‌irst author.

Population

density

improvement

87

Received1 June 2023

Revised10 July 2023

Accepted19 July 2023

InternationalJournal of Housing

Marketsand Analysis

Vol.18 No. 1, 2025

pp. 87-105

© Emerald Publishing Limited

1753-8270

DOI 10.1108/IJHMA-06-2023-0074

The current issue and full text archive of this journal is available on Emerald Insight at:

https://www.emerald.com/insight/1753-8270.htm

1. Introduction

Increasing the density of existing developed areas is of interest to many municipalities, as

doing so promotes sustainable development by preventing urban sprawl and places more

residents in developedareas with access to transit, amenities and employment.However, the

straightforward addition of a high-density residential development comes with challenges:

placing a high-density development, such as an apartment building, in a comparably low-

density area can cause an overlydrastic increase in population density. Intuitively, suchcan

overburden the roads and other infrastructure and resources in the neighborhood, cause a

mismatch in building prof‌iles and disrupt the peacefulness that characterizes low-density

neighborhoods.

In the 1970s, many municipalities began to make initial efforts to increase density in

areas near the downtown (Parolek, 2020). Such is initially done by simply and

straightforwardly changing the zoning from single-family to something considerably

denser. However, as a result, poorly developed high-density housing caused a mismatch in

scale with the surrounding communities, resulting in severe backlash. The backlash then

caused massive downzoning of residential districts and marked many areas as historic

districts to protect existing neighborhoods (Parolek, 2020). Subsequently, there was also a

“Rural Rebound”when residents moved into the suburbs and back to natural amenities

(LaGro et al.,2017).

As such, an incremental and moderatepopulation density solution that involves housing

types with density between that of a single-family home and that of a mid-rise would be

required in certain neighborhoods. The implementation of said housing types would

certainly face challenges regarding both zoning and f‌inancial feasibility. This study

explores ways for missing middle housing (MMH) to overcome challenges using

hypothetical projectsunder representative situations. It starts by discussinghow the cottage

court concept can be implemented to provide affordable housing under the density-based

zoning ordinances in the USA, taking the representative context of Atlanta, GA, before

proceeding to discuss how the adaptive use of the concept could be helpful to mitigate the

social challenges of Blackpool, UK and Jinan, Shandong, China, under various form-based

and zoning-based challenges.

2. Background and literature review

2.1 Missing middle housing

The concept of MMH essentially refers to the types of housing with a density that lies

between the density of detached single-family homes and that of a mid-rise. The housing

type provides incremental population density increase and high quality of life for its

residents and include duplex, triplex, fourplex, courtyard apartment and cottage clusters,

townhouses, multiplex and live-work (Parolek, 2020). Daniel Parolek initially proposed the

concept of MMH in 2010. Then, Parolek (2020) further developed the concept. MMH comes

with a wide array of benef‌it and could simultaneously achieve density, walkability, social

and economic equity and sustainability(Frederick, 2022).

Among these benef‌its pointed out by Parolek (2020), three main aspects are directly

related to this study:

(1) eff‌icient use of land;

(2) matching scale with surrounding low-density community; and

(3) featuring small but livable homes.

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