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?

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.