**1. Introduction**

Housing is second most essential basic needs of humankind outside food. Its impact on the health and welfare and output of man is profound. Therefore housing plays a vital role in a person's standard of living and place in the society [1]. Nigeria has an estimated population of about 200 million people and this implies that urgent attention should be placed on the country housing sector if the housing needs of the inhabitant are to be met. One key issue affecting housing delivery in Nigeria is that the level of housing shortage has not been adequately presented. This is as a result of inadequate and inappropriate statistics and data by the managers of housing in Nigeria [2].

However, there are still attempts to estimate the magnitude of the housing shortage in Nigeria. In 1991, the National Housing Policy specified in detail that to achieve the goal of providing 8 million housing units by the year 2000, 700,000 housing units would have to be built each year; it concluded that this number is necessary to compensate for the housing shortage in the country [3–5]. According to Okonjo-Iweala [5], around 100,000 housing units are built each year, and an average of 80% of Nigerians live in informal housing, which is plagued by problems related to poor quality and inadequate infrastructure that have hitherto been discussed [6].

It is estimated that, in terms of funding, 12 trillion naira (about 45.3 billion pounds) is needed to solve the existing housing scarcity problem [2]. It is projected that in Nigeria's 20-year time frame, an average of 56 trillion naira (approximately

211 billion pounds) is needed each year to meet the demand for housing [2, 7, 8]. Although the exact reasons for the housing shortage vary across the country, the main problem in Nigeria is the low income of residents. This is problematic since privately constructed houses are expected to comply with official planning laws and other costs incurred during the construction of the house [7, 9, 10]. High occupancy rate ranging from 5 to 8 persons per room which is above the official recommended range of 2-4 persons per room in many Nigeria cities is one factor that shows there is housing shortage [11, 12]. One reason for this is that most of the housing stock is traditional in form, and the sharing of one room by more than two persons along with the sharing of individual housing units by several households is a central feature of housing in in many cities in Nigeria.

Since then, huge resources including effort, time, materials and money, have been devoted to planning the Nigerian environment at the national and subnational levels. Nonetheless, the various challenges that have been, and are being addressed have hardly diminished [13]. In fact, the problems of housing shortages, like those of unemployment, physical deterioration, poverty, inadequacies and inequality in service delivery systems have escalated. The incidence and growth of these problems seem to outpace the capacity of government to take them. Nigerians are faced with the fact that their cities are in trouble and that there is an urgent need to do something that will ameliorate the emerging problems.
