Among the basic necessities of man, housing plays an important role. It has an implication on the mental, psychological and social wellbeing of man. A review of many scholars working on housing revealed that both the public and private sectors have contributed in various ways to the purpose of meeting the ever increasing housing demands in Nigerian urban cities. However, despite the intervention of these sectors, the challenges of housing provision for Nigeria still persists.
On the demand side, Nigeria has a huge housing deficit of 17 million homes, with Lagos alone accounting for a 6 million homes deficit. The most dramatic evidence of this endemic housing crisis is in the increasing number of people who are in overcrowded homes or are even in temporary accommodation. On the supply side however, one of the major factors responsible for the huge housing deficit in Nigeria is the fact that houses are not being delivered fast enough in tandem with the population growth, especially in major cities like Lagos, Abuja and Port Harcourt. Consequently, this has triggered a lot of attention for viable alternatives for increasing the supply of housing to mitigate the housing deficit situation in Nigeria. One of the major approaches to resolving this ‘housing crisis’ from the supply perspective is the adoption of offsite construction methods.
Offsite construction is a method of construction by which a component of a building, part of a building, or a whole building is manufactured in a separate specially designated location and then transported to the site where it will be assembled. Offsite construction includes permanent and temporary structures that can easily be relocated, demounted or partially re-used in the future. The concept of offsite construction can be applied to both residential projects as well as other developments such as student accommodation, hotels, hospitals, retail outlets, and bank branches.
Offsite construction falls into two categories based on the product type and materials used: modular/prefabricated construction and mobile homes.
Also known as prefabricated construction, this method describes the use of factory-produced, pre-engineered building units or modules that are delivered to site and assembled as large volumetric components or substantial elements of a building.
Also referred to as manufactured homes, mobile homes are not built completely on site. They come as single units that have already been designed and assembled offsite and transported to site as complete units (ready for use).
In Nigeria, it is quite obvious that the concept of offsite construction has not been embraced on a large scale. This might be due to some of the negative connotations associated with it. Firstly, offsite construction is perceived to be rigid and not easily modifiable for aesthetics reasons. Secondly, there is a fixed cost associated with production and transportation of modules which is generally high due to the cost of energy required to run an efficient production facility. Perhaps the biggest hindrance to the adoption of offsite construction in the local market is the misconception about the durability of prefabricated products compared to traditional construction methods.
These are however largely just that, misconceptions, thanks to the advancement in construction, innovation and techniques that has enabled the production of more efficient precast components. These new inventions introduced in the market are more aesthetically appealing, durable, easily modifiable and take less time to install. More importantly, offsite construction has also been able to address the triple constraints of cost, time and quality common to construction projects.
From the cost perspective, it is a well-known practice in conventional buildings that contractors allow 1% to 2% cost overruns for snagging and ‘call backs’. These costs are considerably reduced in offsite construction. Time savings also have a direct impact on cost. Timely completion of projects can dramatically reduce the risks of cost overruns, which is automatically equivalent to cost savings for the project. Offsite construction techniques have also allowed for housing to be delivered at a much faster rate compared to on-site construction methods. Site preparations can be carried out in parallel with factory production which in turn allows installation to take less time to accomplish with minimal disruption to the existing business and or neighbourhood.
Finally from the quality angle, offsite trials are basically carried out during factory production stage to stress test the system before installation. This assures an adherence to quality. The modules are also allowed to cure over a stipulated time frame before being transported to the place of installation, maintaining quality standards.
Offsite construction addresses the prevailing construction challenges such as wastage, project delays, budget overruns, poor quality and safety issues. It is a well-suited solution that controls project schedules and budgets while increasing quality.
Contributing author: Jude Okeke