Prefab vs. Modular Building: What is the Difference?

Today we look at prefab vs. modular construction methods, discussing the key differences in design, cost, time, aesethetics, and environmental considerations.

By Rose Morrison, managing editor of Renovated

People often speak about prefabricated and modular buildings in the same breath, but they’re not identical. Both options are creative solutions to alleviate housing burdens and make construction more sustainable.

Comparing and contrasting these techniques is necessary to unlock what might be best for you and your loved ones depending on your lifestyles, priorities and budget.

This article is part of a series on: Modular Construction.

Understanding Prefab Construction

Prefab builds are manufactured in separate pieces. Each section has a separate creation process but comes together on-site. Manufacturers may create elements like subfloor sheets and roof trusses beforehand, making it easier to fasten together. Each section matches an aspect of the blueprint like a puzzle. The industry is so streamlined that prefabs may even be assembled in inflatable factories, allowing them to permeate more regions.

Complex rooms, such as kitchens, may have the cabinets included before bringing them to the building location. It is more affordable and streamlined to include these built-in features in prefab sections than to install them during construction.

Constructing a prefab home looks similar to the stick-built process in that the project is still exposed to nature. However, it is much faster, safer and more affordable because manufacturers have fully realized the most prominent elements — they merely need stitching together. Around 80% of putting the space together happens in an off-site location.

An example of a completed panelized home in Lake Whatcom, United States.
Prefab vs. Modular Building
A panelized prefabricated home built by the Seattle luxury architecture firm: Stillwater Dwellings. The home location is Lake Whatcom Washington.
Photography by TJ Simon.
Credit: Stormageadon

Exploring Modular Construction

Prefabs sound much like modular homes, but the main distinction is where they manifest. Prefabs come to life when workers build the structure, and modular homes are assembled off-site and transported to their desired location. They are only sometimes assembled to completion in a factory, but the majority is executed off-site.

This means the plot of your future house could be barren one day and loaded with a move-in ready home shortly after. Modular construction is ideal for getting people into homes quickly, which is why experts often cite them as the solution to housing crises. They are built to last, so decades could go by, and the foundation will still stand firm.

The most significant boon of modular construction is control. You never know when severe weather could impact a project’s timeline or ruin some of the home’s elements. Modular blueprints don’t have to worry about that during construction because it all happens within a factory when workforces have complete agency over the climate.

Despite these distinctions, many consider modular homes a type of prefab build, whereas the reverse is not always true. Prefabs are an umbrella term that could also include manufactured, or mobile, homes and kits.

Modular home
Modular home in Sutton, Alaska
Public Domain, https://en.wikipedia.org/w/index.php?curid=6784815
Source

Contrasting Prefab and Modular Construction

When the primary distinction between these builds is the manufacturing process, what does it matter to buyers which kind of house they choose? Construction experts design factories to facilitate these unique building styles, meaning the parts and finished homes could look and feel notably different.

Modular houses don’t always look the same, but they are better suited for open floor plans because they make the in-house assembly process easier. If buyers work with the manufacturer, they may have more customization options. Prefabs share similar flexibility, though they may be more malleable simply because fewer elements are adhered beforehand.

Does this indicate significant cost differences between a for-sale modular home versus a stick-built? Modular and prefab homes may cost less than other styles because of minimized overhead, labor and operational optimizations. You could get more square footage within your budget than building from scratch or eye a stick-built property.

Knowing notable differences, how do prefab and modular buildings overlap in practice and in terms of their advantages?

  • Takes severely less time to erect than conventional construction methods.
  • Provides more opportunities for quality and compliance checks before assembly.
  • Alleviates worker burgers during labor shortages.
  • Follows similar compliances, rules and zoning laws.
  • Reduces the impact of on-site environmental stressors before completion.
  • Costs less to put together, even considering manufacturing overhead.

Prefab and modular homes are both different from manufactured and kit houses — these follow different building codes despite highly emphasizing factory-made elements. Variations in the housing industry will only expand as manufacturing and robotic capabilities become more refined.

Eco-Friendly Considerations

Both construction methods are known for their reduced environmental impact compared to other building strategies. Long time lines and weather make builds last awhile, waste materials and need multiple project changes throughout to adapt to new designs and circumstances.

The more notable benefit of these houses is how much less they damage the planet. Traditional builds have a wider impact spread than modular and prefab homes. They have reduced site disruption compared to other houses.

It starts at the beginning of the process within the supply chain and manufacturing stages. They prioritize more sustainable materials. Some examples include engineered and ethically sourced wood and recycled and reclaimed steel. Modern insulation is another consideration, as homes phase out toxic and polluting materials.

Though it may seem destructive to transport massive home pieces — or a whole build — to the site, it’s often cheaper than carting mass amounts of individual materials to the location. Shipping finished pieces also ensures there are never excess resources lying around, going to waste.

These buildings are made to last and consider the planet while operational. Prefabs are verified to have fewer adverse operational byproducts and have up to a 45% lower embodied impact than conventional counterparts.

They are generally more energy-efficient than stick-built homes. A comparative analysis revealed a conventional home was 80% less airtight compared to a modular house, making the traditional structure use higher amounts of natural gas over its lifetime. With insulation already implemented and energy-efficient compliance becoming commonplace, it’s expected that prefab homes will be more considerate of these design choices.

Prefab vs. Modular

Knowing the differences, is one version significantly better than the other? It depends on the circumstances of the people living there. Each home will likely provide similar living experiences, but they benefit workers and the planet by being more manageable to create and less harmful to the atmosphere.

If you’re shopping for your next house, prefab and modular homes are viable options that could bring long-lasting benefits for as long as you live there.


Rose Morrison

About the Author

Rose is the managing editor of Renovated and has been writing in the construction industry for over five years. She’s most passionate about sustainable building and incorporating similar resourceful methods into our world. For more from Rose, you can follow her on Twitter.

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