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A review of contemporary systems for industrialized housing Structural Insulated Panel and Platform Timber Framing

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Technology Study

  1. 1. Technology Study A review of Contemporary Systems for Industrialized Housing Structural Insulated Panel and Platform Timber Framing Deasy Darmawan P00351: Architecture, Construction and Industrialisation Prof. Remo Pedreschi 7 December 2009
  2. 2. Introduction Timber framing is a robust method of industrialized housing widely used in the United States of the twenty-first century industrialized housing. Structural Insulated Panel (SIPs) is an engineered wood product providing an alternative which improves building construction speed and insulation performance. The practical and technical improvement of the panels’ performance enables industrial housing developers to increase their level of productivity. In addition, energy-efficient SIP buildings demand a higher market price because of the utility savings they offer to home buyers (Structural Insulated Panel Association, 2007). Home construction has changed little in the last 150 years. O’Brien et al. (2000) stated that homes are still constructed predominantly with sticks of wood nailed together. This has manifested both during the last housing boom between 2002 and 2006, and the fact that most industrial housing developers in the United States still favors the use timber of framing. Initial article research revealed that SIPs are utilized more on smaller scale industrial housing construction, such as custom homes or Habitat for Humanity affordable housing. However, housing developers seems hesitant to use SIPs in mass produced homes. Structural Insulated Panels have benefits over timber framing due to the fact that SIP is more practical, enabling faster construction as insulation is already integrated in the structure of the panel. This raises questions about whether Structural Insulated Panel will replace timber framing in the United States housing industry. Phoenix is the context location of this review because the writer observed the industrial housing growth while living in the city. In the Phoenix area, almost 36 percent of growth in the private economy during that period [2002 and 2006] — more than $34 billion worth — came from real estate and construction (Rudolf, 2009). The first section provides an overview of housing industry in Phoenix Metropolitan Area. The second section outlines advantages of using Structural Insulated Panels. The third section describes disadvantages of using the panel. From industrial manufacturing point of view, the fourth section provides the future possibility of Structural Insulated Panels in industrialized housing. Phoenix Metropolitan Area Phoenix is a fast growing city located in the southwestern part of the United States. The presence of an important educational institution, Arizona State University, major semi-conductor companies, and healthcare service providers have contributed to the major economy and housing growth in the metropolitan area. The city has fourteen urban villages and ten suburban towns which surround it. The majority of people commute between 8 to 128 kilometers by private cars (Figure 1) as a subway system is not available and the bus system is not adequate. A light rail system began operation in 2008, and it is expected to lower dependency on private cars. According to the United States Census Bureau, growth in suburban towns is faster than in Phoenix (Figure 2) due to private developers’ actions. Between 2002 and 2006, the Phoenix metropolitan area has experienced major growth in suburban housing development. The relative ease in obtaining a home loan approval and the steady gains in house prices led to out-of-state investors buying property in Phoenix. Developers responded to the market demand which resulted in sporadic developments in the suburbs. 2| Darmawan, D
  3. 3. Figure 1. Concentric diagram showing travel distance 2008 United States Census Bureau Figure 2. Population growth in suburban town is aggressive than in city of Phoenix 3| Darmawan, D
  4. 4. The housing industry in the area is dominated by nationwide residential housing developers, such as Beazer Homes, Richmond American Homes, and Dell Webb. These developers adopt a “Just- in-Time” system for the production of units, which is commonly used in the United States (O’Brien et al., 2000). In the Just-in-time system, building materials are delivered on site from sub contractors along with their crew just before the material is ready to be installed on site. Many builders prefer this system as the need to store construction material, which can be damaged in the storage process, is avoided. During the construction process, the home builder company acts as a superintendent on behalf of the home owner. It monitors the construction process and ensures that sub-contractors are on schedule. Delays and errors caused by one sub-contractor may affect the project completion and other sub-contractors’ schedules. Therefore, time and accuracy are important. Panel systems have gained popularity among production builders because of their ability to reduce framing errors, to ensure building quality and to maintain construction schedules (Consortium for Advanced Residential Buildings, 2000). Prior to delivering a panel on site, the panel is constructed in an indoor factory. Typically it is a 2x4 inches wood stud with 16 inches on center between stud framing. After the concrete foundation is set and dry, prefabricated panels formed the wall envelope delivered on site. Depending on the house size, it is common in the United States to see builders erect a house frame in one day. Once framing is complete, electrical wiring, insulation and dry wall will come into place. Considering the process of paneling system above, Structural Insulated Panel can provide more benefits than the paneling system. Structural Insulated Panels (SIPs) The Structural Insulated Panel or “sandwich panel” was invented in 1935 by the United States Forest Product in Laboratory (Structural Insulated Panel Association, 2007). It is an improvement over timber frame construction to reduce construction time and to improve energy efficiency in a building. SIPs satisfy building performance criteria while being both sustainable and cost effective (Kermani, 2006). The panel consists of a thick layer of formaldehyde-free foam, such as expanded polystyrene or polyurethane, sandwiched between two layers of oriented strand board (OSB). The OSB board emits less than 0.1 PPM (parts per million) formaldehyde, but it is still well below levels established as acceptable by the U. S. Department of Housing and Urban Development (Structural Insulated Panel Association, 2007). The Oriented Strand Board (OSB) is an engineered wood product made of compacted wood grain which give provides SIPs their structural integrity. The OSB uses flakes of underrepresented wood species, such as yellow poplar or white birch mixed with MDI adhesives under heat and pressure to form the structural panel members (Thelandersson, 97). Thin rectangular-shaped wood strands are arranged in layers at right angles to one another providing the board with structural strength to lateral loads. The cross oriented strands pattern and adhesives are in tension that makes the board resist deflection and warping. Panels are typically manufactured in eight feet heights, with widths ranging from eight to twenty-four feet (Engineered Wood Association, 4). OSB thickness is 7/16” thick minimum (Structural Insulated Panel Association, 2007). 4| Darmawan, D
  5. 5. Panel sizes and forms can be customized. There are no standard joints conducted by building regulations. Based on product literature survey, such as Kingspan, Premier or R-control, typical types of panel to panel joints are: OSB thin, mini SIP and dimension lumber splines. Figure 3 illustrates those joints. Among the three joint types, dimensional lumber spline SIPs are stiffer under the short term loadings and deflect slower under the long term loadings (Rungthonkit, 2009). (a) OSB thin spline (b) Mini-SIP spline (c) Dimensional lumber spline Figure 3: Typical panel-to-panel joints (Morley, 2000) The expanded polystyrene is chemical material made out of hard polymeric matrix and gaseous phase. The foam is easily molded and cut into shape. Its dense porous material is beneficial for thermal resistance and strength flexibility. Expanded Polystyrene (EPS) has a minimum density of 0.9. pcf,, extruded polystyrene (XPS) shall have a minimum density of 1.3 pcf, and the foam complies with the Standard Specification for Rigid, Cellular Polystyrene Thermal Insulation, ASTM C578 (Structural Insulated Panel Association, 2007). According to the United States Department of Energy, expanded polystyrene R-value typically ranges from R-3.8 to R-5.0 per inch. Advantages SIPs and wood frame studs utilize Oriented Strand Board for structural strength against lateral and axial loads. However, expanded polystyrene foam is only used in SIPs. Polymeric thermo insulating materials posses a number of valuable properties such as following: sufficient strength, low density, water absorption, resistance to watering and thermal conductivity (Vaitkus et al., 2006). Therefore, combination Oriented Stranded Board and the foam make SIPs better material than wood framing. Strength The structural longevity of a building is important for both occupants’ safety and for sustainability. Even though each geographical area has different definitions for structural requirements, such as California’s seismic regulations, force of nature is unpredictable and sudden meteorological conditions could become a catastrophic failure for a building. Arizona is safe from tornadoes and earthquake, but it has the monsoon season. During the summer months between July and September, the southwestern states in the United States experience the monsoon due to shifts in wind flow from the west or northwest to a southerly direction. There are two meteorological conditions during monsoon in Arizona that may affect building the building structural integrity: downburst and gustnadoes. Downburst is a strong downdraft that induces an outward burst of damaging winds on or near the surface (Arizona State University Geographical Science). Dust storms occur as a result of downburst. Gustnadoes is where circular of winds develop on the ground and rotate upwards. 5| Darmawan, D
  6. 6. There are three major loads components that affect the building structural integrity: (1) Vertical loads (direct compression), (2) Transverse wind loads (combined bending and axial compression), and (3) In-plane lateral forces imposed by wind and/or seismic loading (racking loads). The structural characteristics of SIPs are similar to that of a steel I-Beam (SIPA). The adhesive used [in gluing OSB and foam core] must be capable of transferring shear and tensile forces across the interface and not deteriorate over time or under the light of moisture (Milner, 2003). The Engineered Wood Association stated that “Structural Insulated Panel is recognized for resistance to lateral loads caused by earthquake or high winds.” SIPs are more resistance to racking loads than stud walls because the foam density flexibility in different level of compression makes SIPs a more flexible material. Images of expanded polystyrene macrostructure (Figure 4) show foam density under different levels of compression (Vaitkus et al., 2006). The American Plywood Association Supplement No. 4 (APA 1983) is the only standard dealing with sandwich panels and provides some limited design information on the uniform transverse or the combined loading cases (Kermani, 2006). a b c d Figure 4: The changes of EPS macrostructure under different levels of compression, %: a – 0; b – 3; c – 30; d – 60 (Laukaitis, 2006) 6| Darmawan, D
  7. 7. Abdi Kermani and Robert Hairstants of Napier University performed an experiment of SIPs racking strength with and without openings and resulted SIPs have stronger racking loads than timber framed wall. They used SIPs with dimension of 2.4 X 1.2 meter with 95-mm-insulating core, 11 mm-grade 3 OSB SIPs and 47 mm X 95 mm C16 timber sections end studs (Figure 5). The panels were placed vertically and their racking strength was tested by applying constant vertical loads at 0 kN and 25 kN. Two panels were jointed at the middle with timber studs and connected with 2.65 mm diameter screw. During the experiment, they applied vertical loads until the panels failed. All panels failed because OSB panels were disjointed from the soleplate. Results of the experiment were compared with stud walls in accordance to BS 5268, the British Standards code of practice for permissible stress design, materials and workmanship. Based on their experiment, the panels’ strongest racking load is 6.37 kN/m, and stud wall is 3.5 kN/m at 25kN vertical loads. The graph (Figure 6) reveals stud walls fail faster as the vertical applied load on wall head increases. Figure 5: Structural Insulated Panel dimension used in experiment 7| Darmawan, D
  8. 8. Figure 6: stud walls fail faster as the vertical applied load on wall head increases.(Kermani, 2006) Kermani’s SIPs experiment result also revealed that SIPs with opening, such as windows and doors are stronger than timber studs. For the experiment, they applied vertical loads at 0 kN and 25 kN on twelve pairs of SIPs with window or door openings. At maximum force, most panels tore at the top corner of the opening. Based on their graph, a 65% opening SIPs are still stronger than timber framed walls. The graph (Figure 7) showing parallel lines between SIPs and timber framed wall, meaning that both materials are weaker as the opening gets larger. Figure 7: SIPs and timber framed wall are weaker as the in larger openings (Kermani, 2006) Forces of nature, such as an earthquake, are a test to the building’s structural integrity because during earthquake lateral and axial loads move in different directions that cause the building to lose its stability. In order to resist, a building material should have higher load and racking resistances. R-Control of Minnesota stated in the case study prior to the 7.2 scale Richter earthquake in 1995, six homes using their SIPs component built in Kobe. All homes located within the epicenter. When the disaster happened, all homes within the area collapsed but the ones built with SIPs stood solidly (R-Control, 1995). 8| Darmawan, D
  9. 9. Thermal Insulation One of the hot keywords in building science is “thermal bridging” (Consortium for Advanced Residential Buildings, 2009). Thermal bridging should be minimized because it reduces energy efficiency of the building by allowing outdoor air to seep into the building. The Consortium for Advanced Residential Buildings (CARB, 2009) group stated that wall studs have lower thermal resistance compared to the wall insulation; the studs can act as a “bridge” for heat transfer. Fiberglass insulation material is typically applied in timber framing construction but it is not too dense. Thus, exterior foam sheathing is one popular solution for providing a continuous thermal break – i.e. a thermal barrier that minimizes the effect of conduction through the framing (CARB, 2009). As mentioned by CARB, double wall assemblies with gaps in between improve the wall insulation. However, it requires a thicker wall. The group performed an experiment to analyze if staggering the framing will improve insulation. Result shows that offsetting the studs only improves the wall performance by R-1 (CARB, 2009). The construction industry has made several attempts to improve building insulation in wood framing method. However, too many layers of materials are required for minor improvements. Structural Insulated Panel provides more effective insulation and air tightness with fewer layers of materials. The polystyrene foam is denser than combination of studs and fiberglass insulation, and is applied throughout the wall surface. Foam core thickness dictates R-value performance. A SIP wall with an 8.9 cm EPS foam core has a “whole-wall” R-value of 14 compared to R-9.8 for a comparably sized wood-framed wall insulated with R-11 fiberglass batt insulation (1Christian et al., 1995). The ability of foam and OSB act as the panel’s structural element replaces the amount of wood studs and fiberglass insulation that exist in a wall. The Oak Ridge National Laboratory (ORNL) performed a whole wall rating to demonstrate the impact of real-world construction techniques on the reported R-value of construction systems (Kosny, 1999). The testing materials were a 3.5 inch core SIP wall, 2 X 4 at 16 inches o.c, 2 X 4 at 24 inches o.c., and 2 X 6 at 24 inches o.c timber frame walls. First, they filled timber frame clear walls with R-10.55 (2 x 4 at 16 in. o.c.), R-10.83 (2 x 4 at 24 in. o.c.), and R-16.36 (2 x 6 at 24 in. o.c.) fiber glass batt insulation. Secondly, they measured the wall frame R value using guarded hot box - a test apparatus that measures the thermal conductivity of full-size walls (Christian, 1999).The guarded hot box test result revealed that insulated timber frame R value is lower, indicating that timber studs cause thermal loss resistance. R-value testing on 3.5 inch core SIP wall reveals the loss of R-1 between the clear wall and whole wall calculation. This experiment data concluded that construction details reduce R-values stated for clear wall configurations (Kosny,1999). Thirdly, the experiment was calculating the whole wall R-value by applying 0.5 inch gypsum board with exterior wood siding on 3.5 SIP walls, 2 X 4 and 2 X 6 timber frame walls. The result is that SIPs outperform timber frame walls by R-2 to R-4. Table 1 below summarizes the experiment data. Even though there is thicker insulation applied in timber frame, thermal loss increases as the timber stud spacing increases. Fiber glass insulation seems to be more the cause of thermal loss than the timber stud. Figure 8: Although timber frame is thicker, R-Value loss gets larger as clear wall gets wider 9| Darmawan, D
  10. 10. Airtight SIP buildings are extremely airtight, thus mechanical ventilation is required to bring fresh air inside and exhaust moisture from the building. An adhesive sealant is used to prevent moisture infiltration through the panel joints. A building with better air tightness will use energy more efficiently and indoor air quality is manageable. Vapour barrier is commonly defined in North America as a material layer, such as plastic or foil sheet with a permeance of less than 1 U.S perm or about 60 ng/PA s m2 (Straube, 2000). This material prevents moisture or water to infiltrate into the building. Timber framing requires vapour barrier, but Structural Insulated Panel does not require because expanded polystyrene foam is a semi-permeable material. For expanded polystyrene (EPS) with a permeability of 5.8 ng/PA sm (4 U.S perms/in), a 140-mm-thick panel (5.5 inch) would have a permeance of 41 metric perms – less than mandated by most codes (Straube, 2000). Affordability Affordability can be measured from cost of material and construction. The cost of material differences between the sandwich panel and timber framing is difficult to compare depending on the panel thickness, number of openings and complexity of building form. Generally, the panel itself costs more than timber framing because it requires more embodied energy to produce the material. On the other hand, the cost of construction using sandwich panel may be less expensive than timber framing. Compactness of the panel material reduces construction time and is easier to transport. The installment process of this panel is simple. The panels are delivered to the site, edges are glued to the wall panel and then they are erected on to concrete foundations by two or three workers who then bolt the panel on the concrete slab. The panel is easy to transport and less subcontractors are needed to assemble the house. These advantages reduce conflicts in managing subcontractor schedules to come to the site. The cost to build a house with Structural Insulated Panel is approximately the same as timber framing construction (Figure 9). The wood frame material cost is less but takes longer hours of labor to install. Structural Insulated Panel cost more but it takes shorter time to install because it is prefabricated, and it provides uniform nailing surface for both interior and exterior finishing (SIPA, 2009). SIPA assures that SIPs wall is always straight as they hear fewer callbacks or need to straighten walls from SIP builders. Depending on the building complexity and use of materials, the cost of construction using wood frame and SIPs could be the same. The more standardized size material use means more savings and less waste of material. 10 | Darmawan, D
  11. 11. 120.00% 100.00% 80.00% 60.00% Labor Cost Material Cost 40.00% 20.00% 0.00% SIPs Timber Frame Figure 9: SIPs and timber frame cost comparison percentages For construction time comparison, a group of researchers from the University of Central Florida Housing Constructability Laboratory were given the opportunity to monitor the construction of two similar homes for Habitat for Humanity (Mullen, 787). One home (99 square meters) used wood framing method and the other (120 square meters) used Structural Insulate Panel. Based on their observation data, less construction time spent using SIPs. Fire resistance Building safety is important as it is related to human life. When a building is on fire, the structure has to stand long enough for egress. Structural Insulated Panel has the same fire resistance as timber frame buildings if lined with 0.5 inch drywall for fifteen minutes. (Morley, 2000). As a case study, Morley presented a case study to demonstrate Structural Insulated Panel air tightness provides fire resistance. In Windfield, Illinois, fire officials set fire in a twelve foot by fourteen foot furnished room built with SIPs for testing purposes. Doors and windows closed after the internal temperature rise to 2000F. The fire extinguished due to lack of oxygen. Disadvantages Design limitation Structural Insulated Panel is an integrated structure and insulation building product that benefits builders to improve construction speed. However, certain restrictions must be followed to maintain the structural integrity of the product, such as the area of opening is 65% maximum (Kermani, 2006); locations are dictated with panel size. Thus, building design is more stringent to the panel size. Another limitation is that plumbing should not be located in exterior SIP walls because of the 11 | Darmawan, D
  12. 12. possibility of condensation or supply lines freezing in cold climates (Structural Insulated Panel Association). An alternative solution is to create an extra framing with timber on the inside face of the SIP walls to conceal plumbing pipes. Sensitivity Structural Insulated Panel building is highly dependent with mechanical equipment to ventilate moisture to the outside. Moisture can spur mold growth, rot, delamination or warp on Structural Insulated Panel. Under higher humidity, the indoor and outdoor temperature differences cause condensation. The key basis to maintain the panel longevity is to prevent air infiltration as much as possible. If installed properly, an airtight SIP building envelope forms the basis of a successful mold control strategy (SIPA, 2007). However, air infiltration problems do not occur immediately. Although air leak test is performed prior occupancy, local climate condition could deteriorate sealant adhesiveness over time. Since moisture can occur at anytime, mechanical ventilation is necessary to maintain exhaust moisture to the outside. Proper dehumidification of incoming air following ASHRAE standards will create an environment where mold physically cannot grow (SIPA, 2007). SIPA suggest that proper HVAC sizing is crucial because an oversized HVAC system will fail to reach the steady operating rate the equipment was designed for. Short cycling HVAC equipment will be less energy efficient and require more maintenance than properly sized HVAC equipment. In February 2002, Structural Insulated Panel Association (SIPA) published a press report in regards to SIP roof moisture damage on dwellings in Juneau, Alaska to investigate the panel’s installation process in that area. According to the report, twenty multifamily dwellings built prior to 1996 damaged due to moisture leak at the top OSB skin of the Structural Insulated Panel. In response to this, SIPA facilitated third party assessment, Joseph Lstiburek, Ph.D., P. Eng., of Building Science Corporation and author of the U.S. Department of Energy Handbook on Moisture Control, to provide scientific investigation for homebuilders, building professionals and manufacturers. Initial investigation revealed that “the pattern of damage in the SIP roofs investigated was concentrated at the panel seams towards the ridges of roof assemblies” (SIPA, 2002). Warm air travels upwards; entering the roof ridges and creates moisture due to cooler exterior temperature. Over time, this moisture built up and soaks “the upper surfaces of the panel joints, OSB panel edges, and the underside of the roofing paper.” (SIPA, 2007). 12 | Darmawan, D
  13. 13. Figure 10: Illustration depicting possible cause of the roof damaged by moisture (Structural Insulated Panel Association, 2007) Lstiburek summarized that the damage caused by the “lack of closure at the joints due to a lack of sealant or the lack of a continuous sealant or the failure of sealant at the joints” (Figure 10). The findings concluded that there are three categories of damage: the first category is no sealants to provide airtight joint. Hence it is purely due to poor workmanship; the second category is sealants applied but in poor quality; the third category is sealant failed in adhesion. The building science team concluded that hostile weather in Alaska has become the team’s major issue in assuring the sealant to adhere. In Alaska, it rains or snows 300 days of a year. Sunshine happens on only thirty days of the year. Humidity is extremely high; it could be as high as 100% humidity. Their further findings are “Where joints were sealed, particularly at lower interior surfaces, no damage was observed.”; “If joints had been sealed at panel perimeters at the lower interior surfaces, failures would not have occurred.”; “The absence of damage away from panel edges or within the plane of the panels discounts vapor diffusion or the lack of a vapor barrier as a causal factor.” SIPA stated that there are trouble-free SIPs in Juneau area because the builders put proper sealants and used proper details. Despite of the high humidity, high level of rain and snow, the building team concluded that the roof leaking situation occurred due to poor workmanships. In response to this, the product manufacturer involved, Premier Building Systems and Insulspan/Idaho, Inc, to provide a mandatory training to builders and installers in Alaska to learn the proper detailing application. Details are important in maintaining good building workmanships. Durability Stewart Brand states in “Shearing Layers” essay that a building consists of several layers (Figure 11): site, structure, skin, services, space plan, and stuff. Site is the geographical setting, urban location, and legally defined lot itself. Structure is the foundation and load-bearing materials that stands the building for a long time. According to him, “structural ranges from 30 to 300 years (but few buildings make it past 60 years, for other reasons).” Skin is exterior surface. Service is the electrical, communication wirings, mechanical and plumbing in the building. Space plan is the interior layout. Stuff is the furniture. During the building lifetime, there are shearing layers of change. Because of the different rates of change of its components, a building is always tearing itself apart (Brand, 1994). 13 | D a r m a w a n , D
  14. 14. Figure 11: In shearing layers, a building is always tearing itself apart (Brand, 1994) The Structural Insulated Panel and timber frame are under the “skin” layer. Depending on the damage cause and condition, the process of fixing or replacing the panel can be tedious and cost more than timber frame. According to SIPA, structural engineer are needed to assess the damage whether it is cosmetic or structural. If the damage is cosmetic, such as moisture problem, then the panel sealant can be fixed from the inside or outside. If it is structural, then the panel should be modified on site or replaced depending on the damage. As the SIP is more expensive than timber framing, the total cost of fixing SIP panels, which is the sum of material, engineer assessment and labor cost, can be more expensive than timber frame. Due to SIPs extreme sensitivity to moisture, it is best to request a professional installer to install it to prevent future problems. Although timber frame consists of more layers than Structural Insulated Panels (Figure 12a, b), fixing cost could be less than Structural Insulated Panel because it is does not require a professional installer to function properly. Timber frame consist of more layer components, such as batt insulation, sheathing membrane, OSB, timber studs and interior dry wall. Depending on the problems encountered and degree of damage, fixing timber frame could be by simply replacing one of the layer components. Another long term problem with Structural Insulated Panel is the foam long term durability. Although they will not sag or deteriorate over time, the graduate process of air diffusion into the cellar structure of the insulation through the closed cell wall in the rigid cellular insulation can reduce the thermal performance (Bregulla, 2004). Expanded foam is the main insulation element of the building. In combination with OSB, it becomes a structural component. If the foam thermal performance decreases over time, then the house will be very costly to repair. If the foam cellar structure is at its maximum performance during the building lifespan, minimum of thirty years, then the material cost and its lifespan is comparable. 14 | Darmawan, D
  15. 15. (a) Timber frame wall components (b) Structural Insulated Panel wall components Figure 12: Timber frame and Structural Insulated Panel wall components 15 | Darmawan, D
  16. 16. Will Structural Insulated Panel replace timber framing in the United States housing Industry? Structural Insulated Panel has good prospects in influencing housing developers to replace timber framing methods with SIPs. It takes a while until developers are daring to use this material in industrial housing as doubts of its long term performance persist. After reviewing disadvantages of using Structural Insulated Panels and be in developer’s side, developers are concern due to the following reasons: lack of workmanships in applying sealant adhesive and the foam core long term durability. Built environment professionals have acknowledged of the material performance, but none of large industrial housing developers in the United States have taken major movement to use Structural Insulated Panel instead of timber framing. As mentioned in the introduction, initial literature research revealed that Structural Insulated Panels are utilized in smaller scale industrial housing construction, such as custom home or Habitat for Humanity affordable housing. It seems that builders are taking little steps learning to master the material. The panel structural performance durability has been tested in laboratory and real time moment, such as earthquake in Kobe, Japan. Thus, it is assured that this material is safe to build in any geographical condition in compliance to the local building regulations. Workmanships and sealant quality should be improved due to material sensitivity to moisture. ---------------- OOOOOO ---------------- 16 | Darmawan, D
  17. 17. References Arizona State University (2009). Basic of the Arizona Monsoon and Desert Meteorology. Tempe, AZ USA. Available from: <> [Accessed 3 December 2009]. Brand, S (2007). Shearing Layers. Urban Design Reader. Burlington, MA: Architectural Press, p. 302-306. Bregulla, J and Enjily, V. (2004) An Introduction to Building with Structural Insulated Panels (SIPs). BRE Construction Division, Centre for Timber Technology and Construction. November. Building Systems Magazine (2003). SIP production climbs 50% in five years. July/August, 16. 1 Christian, J., and Kosny, J. (1995). Thermal performance and wall ratings. Oak Ridge National Laboratory Available from: <> [Accessed from: 1 November 2009]. 2 Christian, J and Kosny, J. (1999). Calculating Whole Wall R-Values on the Net. Home Energy Magazine, November/December 1999. Available from: <> [Accessed 25 November 2009]. Consortium for Advanced Residential Buildings. Panelized Wall Construction: Improving Quality and Minimizing Resources. Available from: <> [Accessed 5 December 2009]. Kermani, A., Hairstans, R. (2006) Racking Performance of Structural Insulated Panels. Journal of Structural Engineering, Vol. 132, No. 11, November, pp 1806-1812. Kosny, J; Desjarlais, A; Christian, J. (1999) Whole Wall Rating/Label for Structural Insulated Panels: Steady-State Thermal Analysis. Oak Ridge National Laboratory Buildings Technology Center. July. Marcin, T. (1987) The Outlook for the Use of Wood Products in New Housing in the 21st Century. Forest Products Journal Vol. 37. No. 7/8, pp 55-61, July/August. Milner, M. (2003). A briefing guide to the use of structural insulate panel (SIP). TRADA Technology Publication, U.K. Morley, M.( 2000) Building with Structural Insulated Panels (SIPs). The Taunton Press. pp. 82. Mullens, M and Arif, M. (2006) Structural Insulated Panels: Impact on the Residential Construction Process. Journal of Construction Engineering and Management. 17 | Darmawan, D
  18. 18. O’brien, M., Wakefield, R., and Beliveau, Y. (2000) Industrializing the residential construction site. U.S. Department of Housing and Urban Development, Office of Policy Development and Research, Washington, D.C. Available from: <> [Accessed 29 November 2009]. R-Control. SIPs Stand Solid Against Kobe Earthquake Project Profile Available from:<> [Accessed 1 December 2009]. Rudolf, J. (2009) Construction that Fueled Growth in the Sun Belt Slows. The New York Times, August 27, 2009. Available from: <> [Accessed 2 December 2009]. Rungthonkit, P and Yang, Y. (2009) Behaviour of Structural Insulated Panels (SIPS) under Both Short –Term and Long-Term Loadings. The University of Birmingham School of Engineering. September. Siniavskaia, N. (2008) Housing’s Contribution to the State Economies at the Peak of the boom. NAHB and Housing Economics Special Studies. Available from: <> [Accessed from: 28 October 2009] Straube, J. (2001). The Influence of Low-Permeance Vapor Barriers on Roof and Wall Performance. Proc. Of Thermal Performance of Building Envelopes VII, Clearwater Beach Florida, December 2-7 2001. Structural Insulated Panel Associations. Technical: Frequently Asked Questions [Internet]. Available from <> [Accessed 3-7 December 2009]. Thelandersson, S and Larsen, H. (2003) Timber Engineering. Wiley: West Sussex. US Department of Energy (2009). The R-Value of Insulation. Available from: <> [Accessed: 30 November 2009]. Vaitkus, S., Laukaitis, A., Gnipas, I., Keršulis, V. and Vėjelis, S. (2006) Experimental Analysis of Structure and Deformation Mechanisms of Expanded Polystyrene (EPS) Slabs. Materials Science (Medžiagotyra) 12 (4) April, pp. 323 – 327. 18 | Darmawan, D