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There is actually no such thing as a modular home. However, that is the common term given to a home that was built using modular construction. The modular construction process means that a home is built in pieces or modules offsite and then delivered to a home site. The modules then have to be installed on a foundation. This process is known in the industry as a “house set”. A house set for a less complex home can be completed in less than a day. A house set for a more complex home with multiple modules and multiple roof lines can last for several days or a week. The objective of the house set is to have the home assembled on the foundation and to have the roof completed and weathered in.
The home is delivered on carriers to the home site with large trucks called toters. The site has to be prepared ahead of time to position the modules in the correct locations for the crane to be able to pick them off of the carriers and place them on the foundation. A home’s modules are typically large and need to be placed near the crane. If there are site limitations, then modules may have to be stored nearby at another location and delivered to the site on the day of set. Flexibility is key when scheduling and planning a modular home installation or house set.
A crane is used to place the homes modules on the foundation. The crane is large and heavy. The site has to be prepared with not only a location for the crane, but be designed to sustain the weight of the crane and the homes modules on set day. The crane operator bears responsibility for the safety of the site during the set. High winds, wet conditions, or poor site conditions can cause a set to be cancelled. The crane operator also has to be aware of nearby powerlines. To avoid electrocution hazards, the crane should be a minimum of 15’ away from any powerlines.
The crane will be optimally positioned near the front or back of a typical home site. However, site conditions and home layout can dictate the crane be positioned in different locations. A crane operator will take into consideration reach and weight of modules to determine the size of crane that must be used to safely install the modules on the foundation.
Set Day: Lifting the Modules
Most sets start early in the morning. The set crew arrives and begins checking the foundation for fit. A modular home is built on jigs in a factory and is delivered perfectly square. Unless the foundation is an engineered foundation, such as Superior Wall, the foundation is built on site and susceptible to field conditions. This means there could be minor imperfections that have to be accounted for by the set crew on set day. This is a normal part of modular home installation. The site manager will work with the set crew to make decisions for the optimum set of the home.
Depending on the area of the country, the crane and set crew may either use braided cables or nylon straps to lift the home from the carriers. Each of these tools require a slightly different process when used to set a home on site. Cables are typically used in the eastern part of the U.S. and straps are typically used in the Midwest and west.
The first module typically takes the longest to set. This is because it is the most important module. Once it is placed on the foundation and the cables or straps are released, it can’t be moved. The positioning of every other module after the first one is dependent on how accurately the first module was placed.
One thing that seems odd to most homeowners/observers is that the modules aren’t lifted level. They notice that they are lifted crooked from the carriers and placed on the foundation. This is done on purpose to aid in the precise installation of the home on the foundation and to promote the tight fit of the modules together. By placing one outside corner of a module on the foundation at a time and then “pinching” towards the middle, a home is perfectly placed on the foundation.
Connecting the Modules
Modular construction is highly engineered. It must meet the requirements of the local area where it is being built along with standard building codes. Items such as snow loads, high wind/coastal areas can impact the type of final attachments that have to be completed onsite.
After the modules are set on the foundation, and in some cases, during the set process itself, straps may need to be installed to connect modules together. In almost all cases, inter-module connections are done below the floor and in the ceiling area giving modular homes superior strength when compared with onsite construction. In addition, engineers may require straps, bolts, or other devices be used to connect first floor modules to the foundation. All of this just enhances the strength and safety of a modular home.
Raising the Roof
Once all of the modules are on the foundation, the set crew will typically turn their attention to the roof. Most modular homes consist of a hinged roof system that can be augmented with panels. A panel is an independent structure that can be used to “fill in” pieces of the roof that couldn’t be built into the hinged roof system.
When a home is delivered, homeowners/observers can’t see the roof. The roof is usually folded flat on the top floor modules. The roof structure is much like a kids Transformer toy. Eaves can flip over, roof sections are raised, peaks are flipped/installed, end-panels are placed or pulled in and…. Presto! A roof appears on top of the home. In most cases, shingling is all but completed at the modular home factory and the set crew will complete what hasn’t been done onsite.
Wrapping Up: The End of the Home Set
The modular set process is completed once the home’s modules are on the foundation, the roof is raised and completed, and site attachments are done. In many cases, a home set is completed in a day. For today’s more complex homes, an average set is done in two days. The efficiencies of modular construction and the speed of the process allow you to go from foundation, to home under roof in just days. Within weeks of the modular home set, you can be moving into to your new custom home!
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