Modular Construction: Green and Pre-fabulous

What is a modular house?  “Modular” or “mod” sounds pretty cool, on par with the “mod” aesthetic.   This term conjures images of flexible furniture, like small little square tables configurable in lots of different ways.

While a modular house is not that flexible, it is made of different parts attached together like Legos.  Seriously.   The modular house is constructed inside a factory, rather than on the lot itself.  It is then transported in pieces from the factory to the lot.   The pieces are then attached together onsite.  The finishing touches are completed on site and voila!  A house.

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Source:  Method Homes

This construction method piqued my interest.  Here’s why:  small houses can be constructed in one to two pieces, the design aesthetic is simple yet complete, plus weather delays are completely avoidable!  But are these houses solid and well constructed?  Are they visually appealing?  How flexible are the design and floor plan options?  Will they look and sell like their site-built brothers and sisters?

The answer to all these questions is *yes.*.  Here is why modular construction is green and pre-fabulous:

#1   Modular construction takes about half the time to build compared to on-site stick contruction.  The average construction time is 3 months (versus 6 months for on-site construction)  Reason?   While your house’s foundation is being formed on-site, the construction of your house has already started simultaneously in the factory.  There are zero weather-related delays because the home is built inside in a controlled environment.  This is particularly appealing if you don’t want to delay construction waiting for winter to end.  It is also very appealing if you, like me, do not want to have to pay regular visits to a construction site for 6+months.

#2  The factory build process is green and eco-friendly by nature.  Building material is not wasted because it is recycled within the same factory.  Lumber isn’t ruined by a rainy day.  There are no gas costs associated with daily transportation of “stuff” back and forth to your lot during 6 months of construction.

#3  The construction is more precise.  Programmed cutting devices and the controlled factory environment make it easier for assembly, measurment, air-sealing,  and quality control measures.

#4   There is minimal disturbance to the neighbors and the physical environment.  Most modular homes arrive on site 80-90% complete.  That greatly reduces the length of time workers are on-site  and minimizes just general trashing of the environment with construction debris and noise.

#5  There is improved site security.  Once the prefab house is set, it can be locked and secured immediately, whereas an open contruction site is vulnerable to theft and vandalism .

#6  Modular houses are built to be stronger than traditional stick-built homes because they need to stand the stress of transportation.   FEMA constructed a study of a hurricane devastated area in Florida, and found that modular homes suffered significantly less damage than traditional stick built homes.  Ref: http://www.fema.gov/library/viewRecord.do?id=2765

#7  Most modular builders can custom design a floor plan.   Design possibilities are endless, with a caveat that the more extravagant the design, the more expensive the house.    Modular builders can work with you and/or your architect to design any home.  In other words, you are not limited to glorifed rectangles and squares 😉

Exterior of a modern modular home with cedar o...

Exterior of a modern modular home with cedar option (Photo credit: Wikipedia)

#8  These homes are appraised and have a resale value equal to that of their traditionally built counterparts.

Here are a few caveats to keep in mind:

–  Modular construction is not less expensive.  The reduced cost associated with less build time and less surplus material is offset by transportation cost or “freight”, the cost of the cranes to set the house in place, and in the city the cost of redirecting traffic for a few hours while the house is being set.

–   Not all modular homes are equal.  Cars are built in factories as well, but there’s a huge difference between a Porsche and a Kia (no offense to Kia drivers out there).  You have to choose a modular builder with a track record of quality and success.

If you decide modular construction is a strong option, here is  how to choose a modular builder:

– find one within a 100 mile radius to reduce freight costs.

-If you value energy-efficiency, sustainability, and green construction practice, find one who shares the same values and demonstrates it with his/her end-product.

-Visit the factory and watch their process.  Get a tour of one of their homes already built and on-site.

– Ask if there is a third party independent rater of the final product.

–  Make sure your personalities mesh as you will have to work together closely.

One parting thought – prefabricated homes  have been a long part of the American dream.  “Kit homes” were very popular from 1910-1940s, with Sears and Aladdin Homes as leading manufacturers.  They shipped lot owners  a “kit” that consisted of numbered/marked pieces of lumber and other building materials.  A  75+page assembly instruction booklet were provided, which homeowners used to assemble their kit and  build their dream home.  The ultimate in DIY house building.  I predict that the factory built method will undergo a renasssaince as we realize its advantages!

http://inhabitat.com/green-guide-to-prefab-the-history-of-the-kit-home/

kit home

Construction Timeline: Foundation

Construction Timeline Part1

I never thought a pile of dirt could be so exciting!

I never thought a pile of dirt could be so exciting!

When the builders began to dig for the foundation, they discovered that it was backfilled with unsuitable material — old trees, bricks, pieces of the old foundation.  They removed it all and replaced with recycled crushed concrete, a suitable sub-foundation for the house’s foundation.  All that other material is prone to decay and rot, which leads to an unstable sub-foundation.

The builders saved a few artifacts for me — two vintage glass cups, original bricks stamped with the brick factory’s name, and pics of a hand dug well they uncovered under the ground.

Recycled concrete – one layer of the sub-foundation

 

After a week of excavation, preparation of the sub-foundation (which is 14′ of compacted crushed concrete!), and installation of the water/sewer lines, the actual foundation for the house arrived.  It is pre-cast and installed on-site in one day.  After watching how quickly and easily it goes up, I can’t fathom why most builders don’t use this type of foundation.  Plus, it’s a great foundation system (see details in my post The Basement Foundation).

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The pre-cast panels arrive on a trailer.  They’re hoisted and placed in position by a crane.  The crew is on-ground to receive the panel and lift into place.  Once in place, they adjoin it to the adjacent panel and seal all seams so it’s airtight.

The completed basement foundation -- in one day!

The completed basement foundation — in one day!

Modular Construction: My Trip to the Factory!

Today I woke up bright and early at 6am, downed a cup of coffee and dry waffle with fruit, and hopped in my car.  I’m getting the factory tour today!  Finally, I get to see the nitty gritty of how a modular house is constructed.  It was raining really hard, but I didn’t care since this was the fun part of the process.A_Colorful_Cartoon_Woman_Drving_a_Nice_Sports_Car_Royalty_Free_Clipart_Picture_101016-156584-687053

I arrived about an hour and a half later in South Fayette, PA, where the factory is located.  The tour began right away.  The factory was in the process of constructing a 36 module hotel to be shipped to Vermont, so only these modules were on the assembly line (alas, no residential homes on the assembly line, but the process is still the same).  Although it was raining very hard outside, I was pleased to see construction proceeding in full force within the factory (so yes, it’s true, there are no weather-related delays).

Inside, the process begins with construction of the floor.  There were 6 floors on the assembly line being worked on simultaneously by contractors.  “These guys only do floors, every day all day,” the tour guide-in-training who was tagging along whispers to me.  “Really?  I tap the actual tour guide — is it true that the same guys do just floors day in and day out?”  “Yes, it is.  They get really good at what they do.”   Once the flooring is framed, it gets wheeled down to a different area where the in-floor plumbing is installed.   The apparatus that the floor is constructed upon is calibrated to ensure the floor remains level as it’s moved to each station.

Several floors being assembled in the factory

Several floors being assembled in the factory

In-floor plumbing installation

In-floor plumbing installation

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Next step:  wall assembly.  There’s a different crew working on the walls.  The walls are braced with steel reinforcements which I’m told site-built counterparts don’t have because they don’t need to withstand the jolts of transportation.   I also see insulation going up here, holes for ductwork being created, interior walls going up.

Note the steel bracing at the bottom of the wall

Note the steel bracing at the bottom of the wall

The modular unit being wheeled down the assembly line.  The wheeling apparatus seen under the unit is calibrated to keep the house level at each step of assembly.

The modular unit being wheeled down the assembly line. The wheeling apparatus seen under the unit is calibrated to keep the house level at each step of assembly.

The roof is next, and this part is interesting — at this station there is the largest-work-table-I’ve ever-seen.

The largest work table I've ever seen.

The largest work table I’ve ever seen.

The ceiling is being assembled very comfortably by roofing contractors on this table.  They are most definitely not climbing up on walls, doing a balancing act 60 ft above ground.   After they’re done, a large crane grabs this roof off the table, hoists it upward and sets it on top of the unit you see to its left.  It’s secured and this unit (which now resembles a house with a floor, 4 walls and a roof) gets moved to the finishing area — this is where the drywall, windows, doors, finishes, etc, etc. etc. are installed.

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Once the house is completely finished, it goes through a quality control measure that is done by a third party.  This is where they do blower testing to make sure air ducts are sealed, along with other basic checks.  Once it passes quality control, it’s ready to be shipped.  I’m sure I missed many steps along the way (like when does the house get wired?), but I think I got the overall big picture.  Interesting, eh?

It was nice to see in live action what I already knew:  modular construction is faster because of no weather related delays and ability to work on multiple floors of the house simultaneously.  It is more precise due to the factory controlled environment.  The surplus building materials are easily stored and reused in the same factory.  There is an independent 3rd party quality control assessment.  Other nice surprises include the area-specific contractors and the ingenious roof assembly process.  Nice!