What are the pros and cons of using a lightweight modular pre-engineered building system (such as Kelly Klosure) versus a traditional rigid frame PEMB?

The end product may seem similar, but the process is quite different. There is no “better” system, rather a vetted business/professional decision to meet owner’s objectives.

Lightweight Modular Pre-Engineered Buildings (Kelly Klosure)

Advantages

1. Relocatable modular panel design, buildings can be easily reconfigured or moved. Panelized building system will help the end-user manage changing site conditions. Our pre-framed panel concept is designed for efficient relocation and reuse. Our unique “anti-syphon” overlapping edge does not require field-applied screws so there’s no need to “realign” holes in the exterior sheeting when reassembling. Panels are simply unbolted and placed in shipping storage frames that are ready for transport and/or reassembly.
2. Designed structurally to IBC 2012.
3. Structural frame, exterior sheathing, and insulation (optional) factory assembled into panels.
4. Breaks down into 3’ wide panels for easy assembly and access to tight spaces.
5. Reusable shipping racks included with building.
6. Quick assembly (four times faster than conventional steel buildings).
7. No column point loads allows for a variety of temporary foundations.
8. Preset anchor bolts not required.
9. Kelly Klosure’s buildings utilize smaller repetitive frames on 3’ centers to create uniform loading around the perimeter of the building. Traditional metal buildings use large rigid frames requiring large column piers and possible cross-ties within the foundation system to support these frames. Kelly Klosure buildings use a simpler thickened edge slab or trench footing foundation without need for any column piers or cross-ties. This makes for a much simpler and less costly foundation system.
10. Buildings have been engineered for loads as high as 180 MPH wind and 200 PSF snow as well as very high seismic loads.
11. The building can be placed on a base plate with earth anchors, or in very temporary situations a wood sill plate and guy wires. Kelly Klosure can provide a base plate and earth anchors with the building allowing you to set the building up on the ground without a concrete foundation.
12. Guy wires and deadmen can be used in lieu of penetrating the ground with anchor bolts if you cannot penetrate the substrate or ground surface with anchors.
13. Kelly Klosure is an official GSA FSS (Federal Supply Schedule) supplier.
14. Fast delivery.

Limitations

1. Up-front capital cost.
2. Post-Design Loading Limitations: Normal items such as lights, conduits, and HVAC ductwork can be attached to the structure of the roof. *Larger items such as large wet pipes for fire suppression systems, large cable trays, and HVAC units can be accommodated on the front side of the design process. If these larger items are to be added “after the fact”, consult Kelly Klosure, and we can determine the best way to accommodate these loads.
3. Coordination of site utility hook-ups.
4. Costume building sizes are far more expensive.
5. Not considered Real Estate as it can be transported to different locations, thus declining property value.
6. 15% more material (on average) to withstand transportation and erection.
7. Non-traditional footing due to uniform loading around the perimeter of the building- potentially more concrete required for continuous thickened slab edge versus isolated footings at traditional column bays.
8. Proprietary Construction Process (Cost Add): “Construction Savvy Crew” required. On-site support is included with the purchase of Kelly Klosure buildings over 24’ wide. This service can be included with the purchase of any Kelly Klosure product if discussed during the proposal process. On-site support, when included, consists of having a field service representative on-site for 2–3 days to assist the crew during the assembly process.
9. Floor panels are an optional item and are only included upon request. A typical building installation would have a concrete slab for a floor.
10. Proprietary Building elements (Cost Add): maintenance and replacement cost of HVAC, electrical, and plumbing system will be higher. Building components over the lifespan of the building will need to be sourced from the manufacturer to ensure compatibility and/or maintain warranty.
11. Door and window options are limited by what’s offered by the manufacturer.

Pre-Engineered Metal Buildings (PEMB)

Advantages

1. Shorter Construction Time: It typically takes less time to construct a steel building systems structure than other building types. This is because the pre-engineered metal building systems components are designed and pre-built to be easy to assemble. Processes that take place on the construction site with other building materials, take place before metal building systems components have even left the factory. Smaller buildings that would take weeks to build, can be up in days. Larger buildings, that would take months, can be up in weeks. 10,000 square ft commercial structures can be completed in just under three months, etc.
2. Lower Construction Costs: Because metal building systems components have been specially engineered to fit together easily, and because the components are cut and prepped in-plant, using automation, cost of assembly is significantly reduced. When metal building systems components arrive at the construction site, the skill level required for their assembly is substantially lower. Your construction costs may be reduced by 60%.
3. Ease of Expansion: Steel building systems have a dynamic design, which can be modified quickly and economically before, during, and after the building is completed, to accommodate all types of expansion. Metal building systems typically can be expanded by removing the end, erecting new framework, and adding matching wall and roof panels.
4. Durability and Weather Resistance: Steel is one of the strongest building materials available today, and can withstand extreme weather conditions including high winds, severe snow storms, hurricanes, and even earthquakes. Steel is also not susceptible to termites, creeping, cracks, splitting, rotting, and fire. There are now options for reinforcing steel against vandalism and fire, and most reputable steel building manufacturers offer a 25 year warranty on their structures, providing you with immediate security on your investment. Metal buildings systems structures are also treated with special coatings like galvalume, that protect their paint and surfaces from rust. Reputable manufacturers typically warranty their paint and coatings over decades.
5. Highly Efficient Material-Utilization: State-of-the-art computer-aided design and manufacturing (CAD/CAM) processes are used to fabricate structural members with high strength-to-weight ratio, minimizing raw material costs and waste. Steel itself has the highest strength-to-weight ration of any construction material, at about 25 times greater than wood (steel frames are actually lighter).
6. Insurance Advantages: Because of its superior strength and fire retardant nature, steel has been proven to withstand extremely harsh conditions, leading insurance companies in most areas to offer rebates of up to 40% to insure metal building systems structures.
7. Minimal Maintenance: Metal building systems require little to no maintenance, and their surfaces are easy to clean with soap and water.
8. Single-source Assurance: One party is responsible for all of the separate components that make up a metal building systems structure. Customer and construction manager do not have to maintain a list of where each component came from, in case repairs under warranty are required.
9. Attractive Finish: Steel construction technology has come a long way since steel “Quonset Huts” hit the market over half a century ago. Nowadays, steel buildings can be finished with the same exterior coverings that structures made of any other building material are. Choose to add a finish that will allow your steel building to match seamlessly with its surroundings, whether they be your stucco house, your garage of wood and masonry, or your paneled storage building. Choose any of these traditional finishes, or use a set of wall and roofing panels with an aesthetic color and surface-texture combination.
10. Sustainable: Building Green with Steel The energy consumption due to the construction and maintenance of buildings, constitutes a sizable portion of our eco-footprint. When you choose a steel building systems structure for your construction project, however, you can be guaranteed that you are making an environmentally responsible decision.

PEMB Overview

Limitations

1. Expansion — Many buildings require additions to accommodate growth. PEMB’s are not easy to add-on to, unless the addition is an extension of the existing building in a direction parallel to the ridge.
2. Roof Top or Hanging Metal Units — The roofs of PEMB’s are typically framed with light gage cold-formed metal purlins. The purlins are not designed to support any additional equipment loads nor can they be easily strengthened. Hence, additional structure must be added to deal with mechanical loads.
3. Durability and Future Value — The metal siding and roofs of PEMB’s fade quickly and are easily dented — contributing to unsightly conditions (seldom does one see a 20-year-old PEMB that visually looks similar to when it was built). Owners should be made aware of this possible decline in the future value of their investment.
4. Buildouts — Finishing construction of a PEMB is difficult. With exterior wall girts spaced at 5 to 7 feet apart, drywall cannot be directly attached without adding additional structure. If the wall needs to be insulated, then an additional wall is generally used. This exterior wall will decrease the leasable square footage. Also, columns are generally large and bulky, making them difficult to hide.
5. Flexibility of Structure — PEMB’s are extremely flexible and deflections are much higher than those of conventional steel buildings. These large movements cause masonry veneers to crack and windows and doors to leak. If suspended ceilings are hung from the roof structure, then large differential deflections due to deflecting roof beams may be apparent.

PEMB Framing Systems

Sources:

Guide to Advantages of Prefab Steel Buildings | BuildingsGuide

Kelly Klosure | FAQ

Kelly Klosure | Benefits