Structural Insulated Panels

As the price of home heating fuel rises with every hike in the price of a barrel of crude oil new home builders are pausing to search other options before going with the traditional wood home. With a maximum R-value of less than R-2 per inch and heat loss at each stud and window header, wood construction is literally full of holes. You can add to that the real possibility of holes and small imperfections where cold air can get under the fiberglass insulation and into the home through electrical outlets and ducts.

There are other options: insulated concrete forms, cinder block, log construction. However, There is now a product that has all the advantages of wood framed buildings - speed, cost - but with insulation that rivals or beats the competition.

Structural insulated panels, or SIPs, are solid, one-piece units that arrive on site ready to install. These units come in the standard 4' X 8' pieces and much larger and can be used as wall, floor or roof for residential and commercial buildings. Each SIP panel consists of a thick core of expanded polystyrene (EPS) insulation sandwiched with oriented strand board (OSB) on the top and bottom faces.

Are They Stronger Than Frames?

The strength of SIPs is equal to the integrity I-beams or I-columns. The solid EPS core is the webbing and the OSB boards act as flanges. The combination of the two (like a rectangular Oreo cookie) makes obsolete many of traditional building materials, that is, it replaces wooden studs, joists, vapor barrier plastic, insulation and air-flow constraints.

The panels arrive perfectly straight and true which mean there is no bowing or curves in the panels. These amazingly perfect surfaces mean that flooring, kitchen cabinets, doors, windows and other additions go on smoothly without endless shimming and cutting. This means that the walls, roof and floor panels go together very quickly, much like an interlocking puzzle game. This speed in the installation saves the construction crews many days of work because there is no traditional framing.

As for load-bearing, How can a chunk of foam stuck between two pieces of OSB support a wall? Tests have shown that in conventional construction, loads are distributed along the studs and joists that typically have centers of 12”, 16”, or 24”. So in an 8-foot length of wall with standard 16 inch centers there are only 7 load points. With a SIP wall the loads are spread across the entire panel and can withstand loads from 3 to 7 times higher than traditional, framed walls.

How They Go Together

SIP panels are manufactured in a factory and then shipped right to the job so they are constructed without interference from the elements: rain, snow and sun. The top and bottom of the SIP panel are grooved, meaning that the foam is recessed to allow a 2 X 6 stud on the bottom and two on the top to hold the walls together. The bottom stud is fastened to the floor and the OSB of the panel fits right on it. The corner panels are put up first and fastened both to each other and the floor studs so that there is immediate strength. On top, one of the two studs overlaps the other to increase the strength. Many SIP manufacturers also offer complete house kits where the builder at the site needs only to put together the pre-cut panels. If there are any additional openings for doors and windows they can be cut with ordinary power tools on site.

How Do They Rate For Fire?

SIPs have passed rigorous fire and strength tests. In fact, when they are installed in accordance with the manufacturers' specifications, SIPs surpass all building codes and pass the American Society for Testing and Materials (ASTM) standards of safety. In buildings constructed with SIPs, fire investigators have found that the exceeded their expectations. In one teats case, the building was subjected to immense heat so that the temperature in the ceiling area exceeded 1,000°F (538°C) and on the floor it was 200°F (93°C). In this case scenario the majority of the wall panels and ceiling remained structurally sound. In addition, the EPS core had held its shape, neither melting nor pulling away from the OSB boards. When the oxygen was taken away the fire went out meaning that in case of a fire no smoldering would take place under the panels or in the core.

In a nutshell, structural insulated panels are just what the energy conservationist ordered. The buildings go up quickly with many times the strength of the traditional home. And because the panels can be ordered in various sizes the wastage is kept to a minimum, which is another point for the environment.

Posted by: TrustedPros
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