From build quality to design flexibility to cost-effectiveness, there are many misconceptions about modular and panelized construction methods — even within the construction industry itself.
Dennis Michaud, Managing Director of Offsite Solutions for CertainTeed, wants residential builders to understand the benefits of modular and panelized construction to help builders offer efficient, sustainable, and innovative building solutions and distinguish themselves from the competition.
In this Q&A, Michaud addresses common myths about modular and panelized construction in residential building.
What is the difference between modular and panelized construction?
Both types of offsite construction share many of the same benefits, such as speed and quality. Modular and panelized construction comply with the same local building codes as homes built on a construction site. Once built, both are also treated the same as site-built homes with respect to mortgages, insurance, etc. The difference is the level of completion in the factory.
Modular homes are built with multiple modules, or “boxes,” that are almost 100% complete in the factory. Typically, drywall, trim, cabinetry, and sometimes even appliances are installed in the factory. This makes for a very quick construction process. For projects where access is easy for large trucks and cranes, and where speed is the priority, modular is a great fit.
Panelized construction is where the walls, floors, and roofs are built in a controlled environment and assembled into the house on the jobsite. Builders typically complete interior finishes, kitchens, and baths on the jobsite – which many prefer. Panelized construction is still much faster than traditional homebuilding, but it is not as fast as modular. For projects where customization is a priority, or where it is not easy to get large trucks or cranes to the jobsite, panelized construction is the right fit.
Are modular and panelized homes lower quality?
There's a false perception that modular homes are low-quality homes. Both modular and panelized homes are built and constructed to the same standards and codes as traditionally constructed homes, just on a significantly faster timeline. In many cases in fact, modular and panelized construction components are engineered to even more rigorous structural standards than required by local building codes due to transportation requirements.
It's also important to note that the quality of modular homes has improved over the years. The materials comprising these homes today are engineered for high performance, and manufacturers are constantly looking for ways to improve their processes and products to build more efficiently and sustainably.
Can you customize a modular home?
Absolutely. There's a myth that a modular house only comes in a square footprint. With this type of home, some people believe that they are structurally limited to a "box" design.
Further, combining panelized and modular construction techniques, for example, gives residential builders and homeowners even more customization options than a modular approach alone. With panelized construction, you can use a specific modular design base and build out from it. Panels can expand on one modular structure or connect multiple structures, which opens the door to a wealth of customization options.
For a residential builder, it's best to encourage clients considering offsite construction to think outside the box when considering their design options. Ask the buyer what they want to get out of their new home and explain how modular and panelized construction works and how one or both can help them bring the vision of their dream house to life.
Are panelized and modular construction types always used together?
No. While combining them can have benefits, most often homes are fully built with panels or fully built with modules.
%20(2).JPG?crop=yes&k=c&w=588&h=442&itok=HCYZWXrj)
Is it difficult to install panels or modules?
Modular homes must be installed by skilled experts in modular “sets.” This involves large cranes and careful manipulation of the modules together on the jobsite. Further, connections between modules – in particular plumbing and electrical – need to be closely coordinated with the factory and is best left to an expert modular set crew.
Panelized construction can either be installed by the manufacturer of the panels or by the builder. For example, CertainTeed offers ONE PRECISION ASSEMBLIES, where the installation of the panels is included in the service.
ONE PRECISION ASSEMBLIES panels comprise windows, doors, siding, roofing, insulation, weather barriers, and moisture membranes. They are customizable and arrive complete at a modular home site. You can use them to build a fully insulated, weather-tight, and sided home in as little as one day.
Are modular and panelized construction energy efficient?
While energy specifications differ between different modular manufacturers, generally homes built in an offsite fashion benefit from tighter air sealing and a high degree of quality control, including insulation install quality.
Alternatively, you can use panels to build an energy-efficient home. While many panelized options on the market only include framing and windows, CertainTeed’s ONE PRECISION ASSEMBLIES panels include all performance attributes of a home, including insulation, vapor and weather barriers, and air sealing. The design of the panels is optimized for thermal and moisture performance based on the local climate, which helps homeowners simultaneously reduce energy consumption and protect against mold growth and other moisture intrusion issues.
ONE PRECISION ASSEMBLIES panels also include options that meet certification programs for energy efficiency, including Energy Star and the DOE’s Zero Energy Ready Homes program, meaning with the addition of solar panels, the home will produce all the energy it needs for heating and cooling (in addition to electricity). On top of that, builders of new or substantially reconstructed homes that use panels to meet energy-efficiency requirements may be eligible to receive a tax credit of up to $5,000 per home based on the 45L energy-efficient home credit.
What do the logistics of modular construction and panelized construction look like?
Logistics are an important consideration for modular construction. The roads leading to the jobsite need to be wide enough for the large trucks which bring the modules, and the site needs to have room to “stage” the modules and for a large crane. Fortunately, modular factories are experts in determining if your site is a good candidate for modular construction and should perform a certified route study.
With panelized construction, the logistics will be easier since you're using smaller elements — panels versus modules — that are more easily transported and stored at the construction site. For homes on tight lots or in areas with narrow roads, panelized construction may be the better alternative.
I know modular construction is fast. How long does it take to build a panelized home?
Timelines vary across panel manufacturers. However, CertainTeed’s ONE PRECISION ASSEMBLIES take a week to manufacture all the panels and one to three days to erect the panels and ensure the home is weather and airtight. This concludes with a blower door test to prove the performance.
By comparison, this same scope takes anywhere from three to five months with traditional construction.
What is the difference between the manufacturing process for modules vs. panels.
Both methods are built in a climate-controlled, interior facility with a high level of quality oversight, both from the manufacturer and from third party inspectors. Both also benefit from a consistent team of highly trained craftspeople in the factory. Because the trades work with each other day in and day out, they feel a sense of accountability to the overall quality, meaning that issues are rarely “kicked down the road” to subsequent trades.
Panelized construction tends to use more automation, benefiting from the equipment and knowledge developed over the past 20+ years in places like Sweden, Germany, and Japan. Because every step of a panel can be made while the panel is flat on roller-tables, each step can more easily benefit from automated cutting, assembling, and fastening.
Because modules are much larger, you tend to see less automation in modular construction and the process may look closer to traditional methods, but many use subassemblies in their factories to fit-out the volumetric modules. Further, because modular typically includes electrical and plumbing systems, these trades are also present in the factory.
How does the assembly process for modular and panelized construction work?
For modular construction, two or more modules are trucked to the jobsite on large carrier trucks. Typically, prior to their arrival, a large crane is brought to the jobsite. Once the modules arrive, the crane either lifts each module directly from the carrier truck onto the foundation or removes them from the truck and sets each in a separate “staging area” on the jobsite so the trucks can leave. Once arranged appropriately on the foundation, structural, electrical, and plumbing connections are made between the modules. This can happen immediately or over the following days or weeks. Regardless, this work should always be done by experts specialized in modular construction.
For panelized construction, typically the carrier trucks and cranes are much smaller. Often, panels are moved from the truck to the foundation by a lull or boom truck rather than a crane. Because panels typically do not include plumbing and electrical, connections between them are structural – typically screws or metal straps in obvious and marked locations. The greater ease of installing panels makes it possible for builders to do this work themselves if they prefer.
In the case of both modular and insulated, the installation of weatherproof panels like CertainTeed ONE PRECISION ASSEMBLIES can happen year-round. You only need 1-3 days without rain or snow, and afterward, the home is fully dried-in and able to be heated for interior work. This ability to build year-round is a huge benefit to builders and developers alike.
What happens if a mistake is made during a modular or panelized construction process?
The most important thing for panelized and, in particular, modular construction is to ensure the foundation is correct. Some manufacturers, such a CertainTeed, measure the completed foundation before production starts in the factory. This typically fits with the curing and backfill process for the foundation. So, while it does not delay the project, it ensures that the offsite built home components are built to precisely match the foundation. Regardless of whether using modular or panelized construction, check with your supplier to confirm how they handle confirming fit to the foundation.
While mistakes in production of modules are rare due to their high level of in-factory completion, unexpected changes to the modules are more akin to renovation vs. “tweaks.” It is especially important in modular construction to ensure you and your factory partner are completely on the same page with the design and when design decisions need to be made.
However, panelized construction is a more flexible fit to foundation and early design decision-making will still ensure a fast and seamless build process. Regardless, on-site changes are possible and no different than doing the same on a traditional, fully on-site build process. For example, CertainTeed’s ONE PRECISION ASSEMBLIES are designed using details familiar to any builder of high-quality homes. All materials used are brand-named products that carry the same warranties and durability you would expect from a top-tier manufacturer like CertainTeed.
Do you think modular or panelized construction could eventually eliminate the need for builders?
Absolutely not. Both methods empower builders to be faster, more cost-efficient, and build at higher quality with less guesswork. However, design decisions, sitework, and project management will continue to rely on the expertise of builders.
In the case of Panelized Construction, most of the interior fit-out (including kitchens, baths, and appliance installation) is done by the builder. This not only enables flexibility of specifications and delaying some design decisions, it also leaves the high-touch, market specific decisions to the builder who knows their customer the best.
Whether modular or panelized, the builder is always in the driver’s seat, and these new ways of building faster are an important tool in their arsenal.
So, which should I use – modular or panelized systems?
That depends on your goals, the site, your geographic location, and the design of the home. If you are looking for the fastest way to build with the least amount of work for your crew – and if your design and site allow for it – modular may be the best option for your project. If, however, you have a complex design, a tight site, or want the interior finishes done by your crew, then panelized construction may be the better option.