|Stick-built Advantages|| Pre-fab Advantages|
|■ More control over final result|
■ Custom design
■ Oversee construction
■ Personally make punch list
|■ No environmental delays|
■ No damage from elements or vandals during contruction
■ Same codes/standards, but generally stronger
■ Cost effective
■ Speedy timeline
■ Conserve your energy
Modular (or prefabricated) buildings are structures that are manufactured in a facility, and eventually delivered to the customer site. The manufacturing facilities are enclosed facilities, and that prevents environmental factors from delaying the construction. Additionally, construction materials are delivered to the facility location, where they are safely and securely stored, preventing damage from the elements and potentially even vandalism or theft.
Modular buildings are designed to the same codes and standards as stick-built facilities but are generally stronger than conventional structures because they need to be able to withstand the rigors of transportation and craning on to the foundation upon delivery. The same materials are used: wood, steel, concrete.
But those factors aside, let's look more closely the project elements, comparing stick-built to pre-fabrication.
Design. One of the few advantages to stick-built previously mentioned is that you, as the customer, will have a higher degree of control of the final result if you go with a custom project. On the other hand, you will be paying an architect for a "one-off" design. The cost of the design is spread out over many projects in the case of modular construction, providing an obvious cost advantage. The same goes for the MEP design; there will be some customization for the electrical design, but that will be cheaper than hiring an independent engineer for a one-off.
Building foundation. Your construction time-line can be accelerated somewhat because the foundation can go in while the pre-fab building is being made; no need to wait for the foundation to be finished before construction begins on the building itself. At least one of the modular building manufacturers claims that the schedule can be 30 to 50 percent shorter than that of a stick-built project.
There are a couple of options as far as foundations go for modular buildings. A slab foundation, which is a large concrete pad, is one. The slab layer construction consists of sand or gravel, at the bottom of the pad. Over that is placed a vapor barrier, which is a thin layer of impermeable material (typically polyethylene sheets) used to isolate the concrete from the damp ground. On top of that goes a wire mesh, and then the concrete. The edges of the concrete are then covered with an insulating material.
Another option is the crawlspace foundation; the modular building is placed on piers and therefore permanently raised above ground level. This is certainly a good option if you plan to build in any area that potentially floods.
In either case, in the permitting process you will need to adhere to local building codes and regulations; it's outside the scope of this article but suffice it to say that stick-built buildings will require permitting and adherence to local rules as well.
Mobilization expense. I think it is safe to say that the construction of a given size structure, inside of a factory, is going to use less man-hours than the equivalent structure at a remote transmitter site (especially a mountain top). There are many possibilities for construction delays at a remote transmitter site. In either case a foundation is going to be necessary, but in the case of the modular building, fewer trips to the site will be required after the foundation is ready.
One of the last steps in a project like this will be the delivery of the modular structure to its intended home. In most cases the structure (or structures) will be delivered by way of a truck and flatbed trailer combo. A crane is used onsite to pick the structure from the flatbed and to set it on the foundation.
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