System

 
 

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The System

I used Structural Insulated Panels to build the house. SIPs are typically manufactured using an expanded polystyrene (EPS) foam core sandwiched between sheets of oriented strand board (OSB). The wiring chases are either cut or molded into the foam before the skins are attached.

I purchased my panels from Korwall Industries in Arlington, Texas. Most of their sales are so-called "processed" panels. That means the panels are cut to size with window and door openings cut and framed. They are available in several different thicknesses with corresponding differences in R-values and weights. I bought stock 8 x 24 foot panels (6" walls and 8" ceiling/roof) and processed them myself. Even though I saved $18,000, I don't recommend it unless you have a warehouse with an overhead crane or forklift. I had a pasture and an old backhoe.

I used 6 inch thick panels for the walls and 8 inch for the ceilings. A 7 1/4 power hand saw will not cut all the way through a panel so it must be flipped and cut on the other side. I used a backhoe with a jib boom attached to the front bucket to flip the panels. A better solution would be a 16 inch power hand saw or something like a Prazi panel/beam cutter. Reciprocating saws are not accurate enough. The blade wanders too much on the bottom side. A chainsaw would work but keeping it square to the surface might be a problem.

After a panel is cut to size, the exposed edges must be framed with dimension lumber. This is done by removing the foam 1 1/2 inch deep along the edge to recess the lumber into. Where two panels are joined together, the lumber is inserted half way into each panel. The foam can be removed with a heating element shaped to cut the foam. It must have some means of regulating the depth of cut for half or full insertion. It can also be abraded away by an angle grinder with a wire cup brush. This too must have depth control. This was the method I used most. It was faster.

My house has slab on grade foundation. I know some of the fellows from up North roll their eyes at such. Fact is, some folks just don't have to burrow into the ground in the winter time. It works quite well here with proper fill preparation. With a slab, the bottom plate is is nailed and  bolted to the concrete slab. The plate must be sealed to the slab. The panel is then placed over the plate.

Before lumber is placed into the edge recess or the panel placed on a plate, construction adhesive is applied in a continuous bead inside both sides of the recess. The panel and lumber are joined and positioned and the OSB is nailed or stapled to the lumber. The fasteners are to hold the pieces together until the adhesive sets.

It should be noted here that other manufacturers may use different methods of joining panels.

Corners are simply butt joints. Eight inch spikes are used for six inch panels, tens for 8 inch and so on. Each spike is fitted with a 1/4 inch fender washer (about 1 1/4 inch in diameter). Two beads of adhesive are placed on the end of one panel, the other is positioned and the spikes are driven through at two foot intervals. Of course, this must be accomplished at the same time the panel is placed on the bottom plate.

 

More info can be found at www.sips.org .