Quick Information on Structural Insulated Panels

Structural insulated panels (AKA SIPs) are durable, energy-saving construction elements. Sandwiching a layer of foam between two exterior sheets, they're solid pieces that are both easy to work with and good for the bottom line of utility costs.

Invented in the mid 20th century, SIPs only started to receive standardized certification recently from international building code and private product evaluators like NTA.

Materials

Structural insulated panels are typically comprised of an insulating core with two durable outer layers. Common exterior materials include sheet metal, oriented strand board, plywood, drywall, and cement. Frequent insulation choices include polystyrene foam, polyurethane foam, and HSC (composite honeycomb).

Usually they consist of two panels of oriented strand board with a polystyrene center. They can be made of many different things, though, ranging all the way from steel to plastic, with fillings as simple as paper and agricultural fiber in the simplest cores.

Benefits

The combination results in a construction material that's both structurally sound and provides high insulation value. SIPs can endure a fair amount of wear and tear over the years, and can be used for walls in any area, from roofs, to walls, to floors (which are especially valuable above spaces with no pre-existing insulation). Their flexibility and ease of use makes them popular elements in modular home kits.

If you're curious about the effectiveness of your SIPs at insulating your house, the U.S. Environmental Protection Agency's ENERGY STAR program has inspection protocols that can help you determine how well they're working.

Structural insulated panels are often relatively light, and efficient from a space saving perspective. This makes them well suited for offsite construction.

SIPs also tend to resist the negative effects of low temperatures and moisture, making them less susceptible to shrinkage and cold creep than traditional timber.

Installation

Structural insulated panels are available pre-cut, making them relatively easy to install. They can be fastened securely to other construction elements, and sealed with finishing layers like plaster. This makes them popular choices for inclusion in modular homes.

If installed correctly, they're relatively airtight, creating the conditions for a low-energy home. They also offer structural stability, which insulation alone can't provide, essentially fulfilling the role of an I-Beam or column, as well as some of the same support as studs and joists, and the protection of vapor and air barriers.

Some SIPs come with a spline to connect them to each other. Others use clever methods like overlapping panels to allow them to be nailed or drilled in.

In the U.S., SIPs are available in widths as narrow as four feet and as wide as 24. In other areas, they tend to range in width from 300 to 1,200 millimeters, with lengths between 2.4 and six meters. Smaller sections are easier to transport and install, but larger sections create better insulation.

Specialty shapes and sizes can sometimes be customized, but they cost significantly more than standardized models.

Cons

Structural insulated panels can be damaged by moisture. They also need to be protected from animals that like to slumber in panels and insulation.

Cost

Structural insulated panels often cost more than other panels but they can be installed much faster. So if you're having them installed, the material costs may be higher, but the labor cost will likely be lower, since fewer people can do the work in less time.

In the long run, SIPs save so much on energy expenses that they can reduce the lifetime cost of a building by as much as 40% compared to standard stick built models.

Typically factory manufactured, their insulation strength and pressure bearing abilities tend to be consistent. Increasingly, however, SIPs can be assembled on jobsites, an especially valuable feature in remote, and less developed locations.