*1.2. Research Area*

Jeddah, one of Saudi Arabia's most traditional and rapidly growing cities, was founded as a fishing settlement 2500 years ago. From 1509 to 1947, Jeddah was walled. However, in 1947, the city wall was removed by the government because of the city's rapid expansion, which can be attributed to two main factors. The first is population growth, fueled by immigration from across the country, and the second is the importance of the city location as a gate for the two holy cities, Makkah and Madinah. From 1947 to 1987, the annual population growth rate averaged 9.5% [9]. According to the strategic plan issued by the Jeddah Municipality in 2009, Jeddah's population was estimated to grow by around 2.25 million people between 2007 and 2029 [9].

During the urbanization process that occurred between 1947 and 1980, unplanned settlements arose (Figure 1) because of the lack of adequate housing for low- and middleincome residents [9]. Subsequently, from 1992 to 2007, the increasing gravity of the housing shortage problem in Jeddah led to an increase in the number of houses occupied by two generations (couples living with their parents), which accounted for 80,000 families, and in the number of families (151,600) living in reclaimed houses in unplanned settlements [9]. As declared by Jeddah's mayor in the strategic plan formulated in 2009, the city faces two main issues. The first is the need for new and adequate housing (approximately 283,000 housing units) to resolve the current housing shortage, and the second entails providing sufficient units to meet the projected housing demand between 2009 and 2029, which is approximately 670,000 units. Two-thirds of these units will be required for lowand middle-income residents. Therefore, in total, around 953,000 new units will be needed in Jeddah up to 2029 [9].

**Figure 1.** Unplanned settlement (Source: authors).

In Saudi Arabia, typical sites are characteristically family-oriented detached houses, referred to as villa-type housing (Figure 2). This pattern is reflected in contemporary neighborhoods in Saudi Arabian cities, which are dominated by large numbers of villas as opposed to apartment buildings. For instance, in 2019, in the administrative area of Alqaseem, villas comprised approximately 57.32% of residential buildings. Moreover, in the capital Al-Riyadh, villas comprise approximately 45.71% of residential buildings. However, in Jeddah, villas comprise only around 17% of the residential buildings in the city. In contrast to other administrative areas in Saudi Arabia, in the Makkah area, apartments comprise 63.38% of the total housing units (Figure 3), accounting for the highest proportion of apartment units compared with those in other administrative areas in Saudi Arabia [10]. The population density of villa-type neighborhoods varies between 15 and 70 persons/hectare, according to structural plans formulated for Jeddah. However, the population density in neighborhoods where apartments are dominant varies between 15 and 200 persons/hectare [11] (Table 1). According to the Procedure Manual for Preparation of Residential Land Subdivision (PMPRLS) issued by the Ministry of Municipal and Rural Affair and Housing (MoMaRAaH), the minimum area of a land lot for a villa should be 300 m2 [12].

**Figure 2.** Villa-type neighborhood (Source: authors).

**Figure 3.** Apartment-type neighborhood (Source: authors).


**Table 1.** Population density characteristics for each type of residential area in each structural plan developed for Jeddah.

#### *1.3. Research Objectives*

The above discussion highlights several issues, namely the housing shortage, an increasing population trend, with low- and middle-income residents accounting for twothirds of the projected housing demand, and the growing trend toward apartment building development and its relation to land lot areas in the city's growth. Of these considerations, population density in villa-type neighborhoods and legislation on land adjustments are key. Thus, the specific objectives of this study are to identify the housing shortage problem and suggest future solutions based on a predictive formula. To be specific, the following four objectives were established:

