Scroll Top
Prefab

MODULAR CONSTRUCTION: INNOVATION IN HOME BUILDING

Prefab_Home_Proto
BUILDING around a core

Some home manufacturers offer a “system-built” prefab home.  The idea of system-built homes was introduced by Frank Lloyd Wright about a century ago.  They define “system-built” as shipping completed home parts to the site where they are assembled, vs. modular, where entire modules are shipped to the construction site. 

construction costs

There are a cost savings.  Some say their homes can be built for $170/sf, but this is just for their structure, MEP, and exterior cladding.  This is also assuming only two stories.  If you are going up 3 stories, there is a 15% premium.  You still need a general contractor to complete the interior finish build out, as they leave an open shell on the inside that needs to be completed.  They also don’t do any site work, excavation, or foundation work.  When you discuss all-in costs with them, they say their homes can be completed for ~$290/sf, and they emphasize that similar homes with traditional construction methods can cost greater $400/sf.  We are still evaluating the all in home costs using their structure, as well as the costs to construct the same home with traditional methods.  Great homes get built all the time for $250/SF.

construction timing and savings

A Manufactured Home can be constructed in as little as 48 days, but that is really just for the structure, MEP, and exterior cladding.  When you include all the site work including excavation for a basement and foundations, as well as the interior finishes, homes can be completed in 7-8 months, but more likely 8-12 months.  This compares to normal home construction that can be 12-18 months. 

Once you have a site, and have completed a site plan, survey, and soils testing, manufacturers can complete an initial design in 2-3 weeks along with the initial budget.  Once you sign a contract for them to build the home, they complete the comprehensive design and budget in 4 weeks.  They claim that after that point, they can start construction in 2 weeks, and that any delays would be from grading, permitting, excavating, or the foundation.

the core

Some manufacturers puts the home’s infrastructure in their “Core”, and then build simple wood framed walls around that don’t have plumbing.  This is similar to (and might be inspired by) Louis I Kahn’s separation of “service” vs. “served” spaces.  Katerra is also working to isolate the MEP in towers in their multi-family buildings.  

Their home structure adds flexibility to home design.  For example, they have wall systems where you can change the exterior cladding at any time.  They also offer mobile cabinets between certain rooms, that can me moved or removed to change the room sizes.

It is important to find a manufacturer that builds the components of their houses with longevity and reduced maintenance in mind.  Some examples are cladding with rainscreen technology, continuous envelope waterproofing, PVC and factory finished steel cladding, Zero Penetration Roof, heat fused TPO roofing membrane, solid Aluminum door jambs and welded aluminum space frames.  They market the following features of their homes:

  • Centralized Mechanical Core / Controls  – centralizes mechanical and controls
  • Up-gradable home core – can add bedrooms, storage, or move walls with moving cabinets
  • Open and Flexible space (what we call “Flexspace”) – open, airy, high ceilings
  • Innovative and Modern Design – open, clean, light
  • Smart Networked home controls – lighting, controls, security
  • Efficient Construction – prefabricated structural panels
  • Thoughtful Design – “zero-jam” doors, easy entry showers, switchable HVAC flow
  • Owner’s Manual – manual for the homes features,  functions, controls and systems
  • Low-Maintenance / Repair Accessible – Core, wall mounted fixtures, accessible systems
  • Sustainable and Green

If you are interested in using a factory build home manufacturer, we can help.  We can also bring in upgraded exterior or finish packages, contact us. 

For information on other prefab home builders, read our article on different prefab systems, designers, and builders.