Most construction professionals are familiar with the “Project Management Triangle,” a concept that links cost, schedule, scope, and quality. Impact any one of these elements of the project, and it will impact the others. Scholars frequently present the triangle as an inflexible set of constraints. Nonsense.
Under any given construction practice, the Project Management Triangle may apply, but it is not absolute. Contractors throughout history have regularly developed or implemented better, faster, and more cost-effective construction methods.
Today, the commercial construction industry is faced with numerous competing and often conflicting priorities, from tighter budgets to greener construction, while still maintaining high quality. This environment requires a careful look at the most advanced construction techniques.
One of these methods is Structural Insulated Panels (SIPs). Panels provide many benefits over other light commercial construction, such as rebar-built structures, concrete masonry units (CMUs), and upslanted concrete. These include faster closing times, high strength, and several important green building attributes.
Building with SIP
SIPs are precast wall, ceiling, or floor components that are delivered to the job site ready to install in sections up to 8 feet by 24 feet long. They are typically made from oriented strand board (OSB) laminated and pressure-cured to a rigid insulating foam core.
SIPs have been produced by manufacturers for several decades and are now used by construction professionals in many types of buildings. Common applications include single and multi-family homes, schools, churches, offices, retail, and most other light commercial buildings.
The design and build process with SIP is simple. The architect provides the construction documents to a SIP fabricator or distributor, who converts them into shop drawings showing the specific dimensions of each panel. After review by all appropriate parties, the fabricator or distributor finalizes the shop drawings, makes the panels, and delivers them to the job site pre-numbered to coordinate with the installation drawings.
Fast closing times
A key advantage that SIPs provide in today’s tight economy is their ability to dramatically reduce dry time. Large, one-piece panels allow contractors to install entire sections of walls, ceilings, and floors at the same time. They eliminate the need for separate on-site framing, insulation and siding jobs, and allow subs to start and finish the job faster since walls, ceilings and floors are plumb and square.
In addition, manufacturers pre-cut window and door openings, including curves, arches, and complex shapes. Depending on the dimensions of an opening, subcontractors don’t need to waste time installing separate headers. The panels also come with pre-cut raceways, eliminating the need to drill studs for wiring.
At a new elementary school built with SIP, the Clark County School District (Las Vegas, Nevada) reduced closure time by nearly 80 percent, from 118 to 220 typical days to just 45 days. “The general contractor was amazed at how quickly the panels were installed,” said Gary Radzat, president, Shell Building Systems, Sebastopol, Calif.), SIP design and installation consultant for Jacob E. Manch Elementary School. “He said he had never seen such a big reduction in hours.” The use of SIP saved the district approximately one million dollars in direct construction costs.
As construction leaders know, faster construction cycles significantly reduce interest payments on construction loans, an important factor in a healthy bottom line.
High resistance and consistency
SIPs are very strong and in most applications are structurally self-sufficient. Designers can use them in wall, ceiling, and floor systems in lieu of other structural elements.
While they are frequently used in one or two-story buildings, they have been used successfully for taller structures. Last year, Western Wyoming Community College (Rock Springs, Wyoming) opened a 28,000-square-foot housing complex with 48 rooms spread over four stories, the tallest self-supporting SIP structure built to date.
In walls, the SIPs can withstand high loads and offer great resistance in the cutting capacities of the transfer diaphragm. These capabilities allow the panels to be used on typical exterior walls, as well as shear walls to resist earthquakes and high winds. Extensive testing of SIPs has demonstrated their use in high-risk seismic areas, including seismic zones D, E, and F.
On roofs, SIPs can be used without a designed truss system and can span long distances, up to 20 feet depending on design parameters. As a result, they can help create open interior spaces by reducing the need for intermediate structural supports.
Designers can also incorporate SIP into floors, typically in applications such as crawl spaces where an insulated floor system is required.
SIPs play an important role in guaranteeing quality finishes. Because they are made in a controlled environment and come in large sections, they allow for straighter walls than is possible with structures built from wooden sticks. Its smooth, even surface can also reduce finishing work by helping to eliminate the need to shim cabinets, windows, and doors.
Green Building Benefits
To help meet green building goals, designers and contractors are increasingly specifying SIPs because of their many environmental attributes. In particular, SIPs reduce energy costs, as well as construction waste, by up to 60 percent, and play a role in improving indoor air quality and supporting recycling.
energy savings
SIPs provide exceptional energy efficiency compared to other construction methods because they combine insulation and structural elements into a single unit.
By contrast, with beam framing or concrete construction, insulation is added after the structure is built. It is difficult to apply fiberglass batts or blown insulation without gaps, especially in corners and other hard-to-reach places. Also, because SIPs come in large sections, there are fewer spaces to fill, resulting in a tighter building envelope.
In evaluating the R-values of full-wall assemblies, the US Department of Energy (DOE) Oak Ridge National Laboratory found that a 3.5-inch-wide core SIP provides a full-wall R-value of 14.1 compared to 9.6 full screen. wall R-Value of a 2×4 framed wall with studs 16 inches on center and fiberglass batts. A 4.5-inch SIP wall also outperformed a 2×6 wall with R-19 fiberglass insulation.
Improved insulation reduces ongoing energy use and costs, as well as helping to reduce HVAC system requirements. At the Las Vegas Manch school, project consultants estimate that the SIPs cut the capacity of the HVAC equipment needed by approximately half.
Additionally, energy efficient building materials such as SIPs can qualify commercial building owners for a tax deduction of up to $1.80 per square foot.
The lower operating costs of a SIP building can be a key market differentiator, helping developers more easily sell or lease commercial space.
Reduction and recycling of construction waste
Rebar construction generates large volumes of scrap by cutting standard size studs and joists. Since SIPs are manufactured in a controlled environment, more careful materials management is possible than on a job site. In addition to reducing the environmental impacts created by a large waste stream, SIPs can reduce disposal fees.
Many SIPs are 100% recyclable and have foam cores made with a specific level of recycled content. OSB skins come from fast-growing renewable trees and are manufactured using a high percentage of each trunk for efficient use of resources.
indoor air quality
Because SIPs provide an airtight building envelope, they help reduce infiltration of common contaminants such as radon, mold, pollen, volatile organic compounds (VOCs), lead dust, and asbestos. Manufacturers often produce SIPs without the use of CFCs, HCFCs, or formaldehyde, and VOC-free sealants are available. Along with other low-emitting building materials, SIPs can help maintain healthy indoor air, which the US Environmental Protection Agency (EPA) reports is linked to employee performance and attendance and students.
LEED points
Given their multiple environmental advantages, building professionals can use SIPs to earn up to 23 points in the US Green Building Council’s (USGBC) Leadership in Energy and Environmental Design (LEED®) rating system for the new construction classification system. Depending on the project and overall design, the key point categories to consider are “Energy and Atmosphere”, “Materials and Resources”, and “Indoor Environmental Quality”.
Conclusion
Planning, designing and constructing commercial buildings is more challenging than ever. To survive, and even thrive, in the bear market requires new ways of thinking. SIPs are a tried and trusted construction technique that offer a way to greatly improve light commercial construction.
