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Bob and the Home Again crew visit with Steve Thompson, general manager of the Premier Building Systems' Fife, Washington plant in the shadow of Mt. Ranier for a step-by-step tour of the SIPs fabrication process.
At the first stop Steve's crew demonstrates how the wiring chases are "drilled" through the foam core of Expanded Polystyrene (EPS) with a heated up wire called a "hot or nickel-plated wire". Following the architect's exact specifications, round holes are precisely cut creating electrical chases every four feet through the panel so that wires can be run virtually anywhere in the roof or wall system. Recesses are also cut along the edges to facilitate the splining process by which the panels are attached to each other on the job site.
The lamination station is the next step. Here the foam core runs through the roll-coater which rolls glue onto both sides of the EPS literally pushing the adhesive about 1/16" to 1/8" into the EPS.
The glue is 2-part water-based latex adhesive. The foam panel is then laid on a sheet of oriented strand board (OSB) and extra glue is handrolled on to cover any spots that may have been missed in the roll-coater.
Finally a second sheet of OSB is placed on top completing the "sandwich". Another sheet of OSB is placed on top of that and the entire process is repeated. When six "SIPs sandwiches" are finished and stacked, they are rolled into the press where they sit for about an hour with 1000 psi pressing on top of them. There is no heat involved as this is a pressure laminated process.
Once out of the press, a 1 1/2" recess for dimensional lumber is routed out of the foam along specified edges with a "foam hogger". The lumber provides a surface to nail onto and completes the system. The outside edges of the panels which were routed out back in the foam room are left exposed so that they can be splined together on site.
Although Premier traditionally uses an hydraulic tensile tester to ensure the strength of their panels, for a dramatic demonstration Steve placed 5700 lbs of red bricks on a SIPs panel with only the slightest bit of deflection becoming apparent.
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