Modular construction
In a 2018 Practice Note, the NEC states that the benefits obtained from offsite construction mainly relate to the creation of components in a factory setting, protected from the weather and using manufacturing techniques such as assembly lines with dedicated and specialist equipment.
[citation needed] Currently, the design process of modular construction projects tends to take longer than that of traditional building.
Therefore, the weight difference of a traditionally built house and a prefabricated structure will mean that foundations needed will be smaller and faster to build.
The ability to coordinate and repeat activities in a factory along with the increased help of automation result in largely faster manufacturing times than those of on-site building.
A team of five workers can assemble up to six 3D modules, or the equivalent of 270 square meters of finished floor area, in a single work day.
However, current scheduling methods assume the quantity of resources will never reach zero, therefore representing an unrealistic work cycle.
A modular factory handling a single project at any given point is rare, and would produce low returns.
Hyun and Lee's research propose a Genetic Algorithm (GA) scheduling model which takes into consideration various project's characteristics and shares resources.
[4] The production sequence of this algorithm would be largely affected by which modules need to be transported to which site and the dates they should arrive.
Panels run a high risk of suffering minor or major damage when being transported through land.
The factory would need to temporarily stop production of other panels to replace this one, increasing the overall manufacturing hours and therefore cost.
Assembling components in a factory off-site means that workers can use the repeatability of the structures as well as the use of automation to facilitate the manufacturing process.
By standardizing the overall design of structures, work which would usually require expensive workers with specific skills (e.g. mechanical, electrical and plumbing) can be completed by low-cost manufacturers, decreasing the total salaries cost.
Project such as student accommodations, hotels and affordable housing are great candidates for modular construction.
Meanwhile, if the project is (for example) a modern beach house with highly irregular wall spaces and ceilings, traditional construction methods may be preferable.
Modular construction constrains all manufacturing activities to a ground level, clean space with fewer workers needed.
Of the general and specialty contractors surveyed, 78% and 59% said that the largest safety impact was the undergoing of complex tasks at ground level.
[7] The reduction of heights at which workers need perform tasks on subsequently reduces the fatality risk they experience, greatly increasing the overall safety of the industry.
[6] Manufacturing plant workers were more likely to be struck by an object or equipment (37.1%) and fracture and amputation had the same injury type frequency at 27.3%.
