Why is Modular Green? PDF Print

Definition of Modular

For clarity, I would first like to define the term modular.  Modular refers to homes that are constructed in “Modules” or sections off site and then assembled on site into a complete home.  These modules can be finished off site with painted drywall, cabinets and doors installed and all plumbing and electrical run throughout the house.  The sections are joined together at the jobsite and set on the foundation.  Once they are assembled, the joints between sections are finished; the balance of the siding is installed, roofing is completed, porches and garages are added, flooring is installed, plumbing and electric are tied in, mechanical systems are installed and appliances and fixtures are completed.These homes are constructed using the same methods as conventionally built homes with a few exceptions.  They incorporate approximately 30% more materials so that they are stable during transportation and erecting and they require about 30% less labor.  If they are built with conventional materials you may be wondering how they add to the green process of building?

Three "Green" Strengths of Modular Building

1.   Modular homes are built in a controlled environment with materials that are stored in that same environment.
2.   Modular home construction is an efficient method that cuts down on wasted lumber and excess jobsite scrap.
3.   The assembly process involved in modules allows for tighter houses with fewer gaps for air infiltration.
 
Let’s take each of these items separately and dissect them to understand their benefit to the green building process.

Controlled Environment

We are all aware of the concern over moisture and mold in the construction process.  However, mold is not the only problem caused by excessive moisture. Moist wood will move and twist as it dries resulting in stud alignment problems.  Moisture also can cause nails and screws to move in the wood and pop out over time. 

 

The great thing about Modular construction is that the wood is never wet.  Just like the finished cabinets in your kitchen, a modular home is dry from delivery to the factory until it is assembled on site, the wood never gets wet.  The assembly of modules takes place in controlled environments that are free from the effects of outside weather.  All modules are wrapped in plastic before transport and then once the modules are set, the roof is joined and covered to prevent the entrance of moisture.  Moisture has little chance to affect the house and no chance to promote the growth of mold.

Less Wasted Materials

There are several ways that modular construction can conserve on wasted materials: 
  • Modules can be constructed in sizes that allow for maximum use of dimensional lumber.  Studs are usually ordered in pre cut sizes on conventional jobs, but floor joists must be cut to fit.  With pre constructed modules, the dimensions of the module can be sized so that the floor joists do not have to be cut.
  • In conventional framing, when the house is complete, the final scrap is thrown away because the expense of moving and storing it is too costly. On the contrary, small scrap that is generated at the factory during the production of modules can be stored and used for the next house.  This scrap goes beyond just wood materials.  Excess insulation, partial tubes of adhesive, caulking and other small items that would be thrown away on a conventional jobsite can be saved and reused.

Reduced Air Infiltration

Modular construction of walls and ceilings starts from the inside out.  Drywall is placed in position and then wall studs and ceiling joists are built on top.  This process allows for easy access to the exterior of the house.  Gaps in construction can be easily sealed to create a tighter exterior wall.  Ceiling systems can be insulated before roof rafters are installed which allows for full access to perimeter spaces.  In conventional framing, these areas are sealed as much as possible, but can never be accessed as well as in the modular method.

Conclusion

If you want to step your construction project up to the next “Green” notch, consider going modular.  The reduced labor will bring your project cost down and the “green” benefit will help to preserve our environment for the next generation.
 

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