The traditional method of building a new home is hiring a local builder and having them construct it on-site using wooden framing, otherwise known in the industry as stick-built. But did you know there’s another way of building new homes? It’s called prefab (short for prefabrication) home construction, and it may even save you time and money. If the largest home builders in the country use prefab, maybe there’s something to it.
Panelization is the prefab method of choice by larger home builders. With panelization, a home’s structural components, such as the walls and roof trusses, are manufactured in a factory and then shipped to the build site where they are finished similar to a wood-frame home.
What prefab options are available to individuals wanting to build an entire home that way?
It depends on the type of home. For hypothetical purposes, let’s say you’ve already purchased your land, verified the minimum square footage required, and any other community requirements. You have your heart set on a two-story home, around 2,000 square feet, and with a two-car garage.
Great, let’s see which form of prefab home construction makes sense.
Based on the home description above, manufactured homes would not work because they’re one-story, and even if you wanted a a single-story home, your new community doesn’t allow manufactured homes. Tiny houses are out of the question since they are usually around 400 square feet, and the community guidelines require a minimum of 1,500 square feet.
That leaves two building systems that would work well for your ideal home: modular and structurally insulated panels (SIPs).
Modular Home Construction
Modular homes get built in a factory in transportable sections or modules. The building materials benefit from the ideal conditions found inside the factory, and the process experiences fewer delays — no bad weather to stop construction — meaning quicker turnaround. Another benefit is that tools and materials can be stored nearby, alleviating the risk of materials shortages or on-site thefts. And factory conditions are typically better and safer for employees.
What are the challenges of modular homes? Transportation is a big one: Each module is transported by truck and trailer to the homesite, creating the risk of the home being damaged in transit or traffic issues. The number of modules and rigs depends on the size and design of the home. There’s also less customization available than for a traditionally built home because of the manufacturing process.
The best way to envision the completed product, once the builder assembles the modules, is to look at a conventional stick-built home — the modular home should not be any different, from the framing, plumbing and electrical to the insulation and drywall, and right on down to the local codes.
SIP Home Construction
Structural insulated panels replace the need for traditional framing, insulation, vapor barriers, full exterior sheathing, and electrical conduit and boxes throughout the exterior walls. A standard SIP consists of a sandwich of two oriented-strand boards (OSB), “the bread,” with expanded polystyrene (EPS) or polyurethane insulation to create the “meat” of the sandwich, completing the structural wall system.
The SIPs are structurally sound since they create a continuous beam of sorts. Picture a wide-flange steel beam or I-beam, as they’re often referred to because they look like a capital “I” in cross-section. The OSB sheathing acts as the flanges, and the insulation becomes the web or vertical part of the I-beam. This SIP structure creates impressive strength for long spans and open floor plans.
The energy efficiency of SIPs depends on the thickness of the insulation and whether you choose EPS or polyurethane. Some manufacturers will customize the SIPs, so they are ready to be quickly assembled on a foundation. Large precision cutting machines will even cut rough openings in SIPs for windows and doors.
Once the SIPs arrive on the build site, a house can be dried-in, meaning the exterior shell has been completed sufficiently to keep out the elements, and it becomes ready for interior and exterior finishes. Speaking of which, one benefit to this building systems is being able to visit local design centers and extend the deadline to select your finishes.
Which Building System Is Best?
As always, it depends on more variables than the above hypothetical home and community. It may even be possible to combine both building systems. Which one will create your open floor plan with vaulted ceilings, including the quality, durability and efficiency you want for your home?
Is It Modular?
The modular home would take a little longer in the factory since they’re constructing the sections of the house in separate modules. Additional lumber is used to strengthen the structure as it must be built to withstand the rigors of road transportation.
Your selections will likely need to be done up front before you sign an agreement with the manufacturer — plan on visiting the factory design center for a marathon selection process.Some manufacturers may have local design centers for you to make your selections. When shopping around for a manufacturer, be sure to learn the extent of the selections you will have available.
Or Is It SIPs?
With the SIPs building system, the priority is to finalize the architectural design of the structure and the type of interior and exterior finishes, not necessarily the actual finishes. This way, the foundation can be started at the same time as the SIP system. It’s easier to determine that you want solid hardwood floors than the exact product selection. Likewise, you may know you want a stone or brick façade, and the foundation can be designed to accommodate it.
A faster start and quicker dry-in time are possible with the SIP system. Once your home is dried-in, you can take your selection samples to the newly formed spaces and see how they’ll look. Your builder can even create mock-ups of your exterior selections to make your decision process more manageable. Last-minute design changes may cost you more; however, it’s nice to know you can change your mind and not be stuck with something you don’t want.
The choice is yours, and either of the above prefab building systems assembled by an experienced builder will result in a quality, efficient and durable home.