What is a Modular Building?

Modular Building

Modular buildings are buildings that are made in segments, sections or individual bays. These are built within a factory environment. Once complete each section is then is delivered to the site, separately on the back of a lorry. These modules are then connected on-site to form the overall building, which can be made up of many individual sections, often stacked to create multiple storeys.
A section or individual bay typically has at least one open side, where it will connect to the next section, whereas a portable unit/cabin (for the old school – Jackleg Unit). This is essentially a box, transported with all four sides as a complete building.

Portable Buildings

What came first? The portable building (all four sides) or the modular building bay (three sides). I am sure some very clever historian may prove me wrong! But I will say the portable unit or jackleg unit came first. In the very days of the industry jackleg units were designed for the construction industry. They wanted a simple but complete unit (all four sides) that could be transported to and away from the construction site. This design had jacking legs, where you could actually jack the unit off and on the lorry bed, hence the terminology of “jackleg unit”.

I am sure if we dig deeper into the history of the “portable” or “relocatable” or even “Prefab” designs. These phrases will appear well before the phrase “modular”. And, this would be correct, the traditional “prehab” design would probably appear before all other designs, but that is another story and certain another blog post.

Modern Methods of Construction (MMC)

One issue which has been highlighted by increased use in the housing sector, alongside other Modern Methods of Construction (MMC), is that ‘modular’ may not be the best description for these buildings. A basic definition of modular is: “composed of standardised units or sections for easy construction or flexible arrangement”. Whilst this undoubtedly describes the modular buildings we manufacture today; it can also apply to many other types of construction.

This may be one reason why official government documents now classify these buildings as “Category 1 Modern Methods of Construction (MMC): 3D offsite (volumetric modular)”. It can be confusing at times and it’s not difficult to see why the industry still refers to “Modular Buildings”, though perhaps the most accurate term, and one which is gaining traction, is “Volumetric Modular Buildings”.