News Article

8 Disadvantages and Problems with Structural Insulated Panels

Struc­tur­al insulated panels (SIPs) first gained attention in the 1970s for their high level of insu­la­tion, air tightness, and strength over wood framing. However, over time, dis­ad­van­tages with struc­tur­al insulated panels have caused builders and archi­tects to evaluate the trade offs between benefits and problems with SIP. An excellent alter­na­tive wall system which solves many of the problems of SIP is the Bautex Block Wall System. Bautex Blocks are insulated concrete blocks that are moisture‑, fire‑, mold‑, rot‑, and termite-resistant. Also, Bautex Blocks offer design flexibility.

What are Structural Insulated Panels (SIPs)?

Struc­tur­al insulated panels (SIPS) are building panels used in walls, floors, and roofs of light com­mer­cial buildings and homes. SIPs are 4- and 8‑inch thick rigid foam panels, sand­wiched between two stiff sheathing materials. Either expanded poly­styrene (EPS), extruded poly­styrene (XPS), polyurethane (PUR) or poly­iso­cya­nu­rate (PIR) is used to make the foam. With EPS and XPS foam, the foam and sheathing is pressure laminated together. With PUR and PIR, the liquid foam is injected and cured under high pressure. The most common sheathing boards are 716 inch thick oriented strand boards (OSB). Other sheathing materials include sheet metal, plywood, fiber-cement siding, magnesium-oxide board, fiber­glass mat, gypsum sheathing, and composite struc­tur­al siding panels. The SIPs are also known as struc­tur­al foam panels, foam-core panels, stress-skin panels, and sandwich panels.

SIPs are made under con­trolled con­di­tions in a factory. One advantage of SIP con­struc­tion is it produces straight walls. SIP con­struc­tion can provide higher levels of insu­la­tion, air tightness, and strength than tra­di­tion­al framing. However, there are dis­ad­van­tages and problems with SIP construction.

1. Fire Safety Problems of Structural Insulated Panels

Some SIPs, par­tic­u­lar­ly those con­struct­ed with OSB, plywood, and composite struc­tur­al siding panels, do not have suf­fi­cient fire per­for­mance ratings. Buildings con­struct­ed with SIP may put occupants at a high risk of burns and smoke inhala­tion, par­tic­u­lar­ly if the sur­round­ing drywall is faulty.

2. Moisture, Mold, and Rot Problems of Structural Insulated Panels

Moisture problems with SIPs panels can occur, espe­cial­ly if using facing made of OSB or plywood. OSB and plywood sheathing are subject to mold and rot. Mold is unhealthy to the occupants and rot reduces the struc­tur­al capacity of a building. Panels with water­proof surfaces, like fiber cement siding, will resist the growth of mold and rot.

3. Insects, Rodent, and Termite Problems of Structural Insulated Panels

Insects and rodents can be a problem for SIP panels because the foam provides a good envi­ron­ment for the pests to live. Man­u­fac­tur­er guide­lines for pre­vent­ing these problems suggest applying an insec­ti­cide, like boric acid to the panels. It is also essential when using OSB and plywood facing, to treat for termites.

4. Durability Problems of Structural Insulated Panels

Long-term dura­bil­i­ty of struc­tur­al insulated panels may be a problem with those con­struct­ed with OSB or plywood. If OSB or plywood gets wet, the walls may dete­ri­o­rate and rot.

5. Structural Insulated Panels Lack Thermal Mass

SIPs typically have a high insu­la­tion rating. However, a dis­ad­van­tage of SIPs is they have low thermal mass compared to insulated concrete products, like Bautex Blocks. High thermal mass is important because it helps stabilize the tem­per­a­ture within a structure and decrease energy con­sump­tion. For example, in hot climates, a concrete structure absorbs cool air in the evening and stores it within its mass. During the warm day, the structure will stay cool and so will the interior of the building.

6. Structural Insulated Panels are Expensive

According to a study by the Uni­ver­si­ty of Colorado Depart­ments of Envi­ron­men­tal Design And Economics, the cost to frame a small scale res­i­den­tial house with SIPs is approx­i­mate­ly 10 percent greater than stick framing.

7. Modification to Structural Insulated Panels are Pricey

It is crucial for main­tain­ing the budget during SIP con­struc­tion to get the order to the factory correct. Mod­i­fi­ca­tions to the design, once completed by the factory, are possible, but can be quite expensive and not easily achieved.

8. Structural Insulated Panels Construction Considerations

Because SIPs are panels, the building design of a SIP structure is best planned to coor­di­nate with the panel’s dimen­sions, without excessive jogs, non-90 degree angles, or bump-outs. A non-panel friendly design will increase waste, escalate costs, and diminish the per­for­mance of the structure.

A Better Wall Choice Over Structural Insulated Panels

The Bautex Block Wall Assembly is an excellent wall system over SIPs because Bautex is a high-mass material that is moisture-resistant. Therefore, Bautex is energy-efficient and mold- and rot-resistant. Also, the Bautex Block Wall System is termite- and fire-resistant. A further advantage of Bautex Block Wall System over SIP con­struc­tion is Bautex has more design flex­i­bil­i­ty and can easily add complex archi­tec­tur­al contours and curves.

While the Bautex Blocks create an excellent wall system, they are not applic­a­ble to roofs. Utilizing struc­tur­al insulated panels on the roof of a Bautex Block building would further create an energy-efficient, air-tight structure. The pre-insulated, pre-engi­neered SIPs are perfect for large spans of roofing and will con­tribute to an energy-efficient, air-tight structure.