Extreme Panel Technologies

Extreme Panel Technologies manufactures Structural Insulated Panels (SIPs) and sells panel kits for custom and pre-designed homes, with focus on high-performance building envelopes. The company has been making SIPs since 1992, starting in a 500-square-foot shop and scaling up to manufacturing across the United States. If you're considering a SIP-based ADU kit, Extreme Panel is one of the established players in this segment.

SIPs are engineered panels made by laminating a thick layer of expanded polystyrene (EPS) foam insulation between two sheets of oriented-strand board (OSB). A 6.5-inch SIP wall panel typically has an R-value around R-24, which outperforms traditional stick-frame walls (R-13 to R-19 with insulation) by a significant margin. Roof panels are thicker, often 12 inches or more, achieving R-50 insulation. That performance comes from the foam core: EPS foam has an R-value of roughly R-4 per inch, so a 6.5-inch foam core yields R-26 before the air-sealing benefits of the continuous foam envelope factor in. In practice, SIP buildings use less heating and cooling energy than comparably sized stick-frame homes, assuming the air sealing is done well at penetrations and joints.

Extreme Panel's pre-designed packages offer a catalog approach: you pick a house plan that meets your needs (in terms of size and layout), Extreme Panel manufactures the corresponding SIP kit, and a contractor assembles it on your site. The Astro House is 1,045 square feet with two bedrooms and costs starting around $50,000 for the SIP shell package. The Vega House is 1,345 square feet with two bedrooms, starting around $58,000. For a slightly larger footprint, the Rigel House is 2,300 square feet with five bedrooms, starting around $72,000. The Columba is their largest standard option at 2,550 square feet with five bedrooms, starting around $139,000. These starting prices are for the structural SIP shell only: walls, roof panels, and floor systems. They do not include the final roofing membrane, windows and doors, interior finishes, mechanical systems, or installation labor. The actual total project cost is substantially higher once you add those items.

The advantage of pre-designed models is speed and cost. Extreme Panel already has the engineering done, and manufacturing can begin as soon as the order is placed. Custom designs are possible but require additional engineering and design work, which adds both time and cost to the project. For ADU applications where you want to move quickly and don't need unusual dimensions, a standard model often makes sense. For a tight urban lot or a site with specific constraints, custom panels are available but the timeline and cost scale accordingly.

What's included in an Extreme Panel SIP kit is the panel structure itself. Wall panels come pre-fabricated with doors and window openings already cut, and they're sized and arranged so they stack and connect on-site. Roof panels are likewise pre-cut for the specific design. Floor systems are included as panel assemblies. The kit does not include windows, doors, roofing material, interior wall framing for partition walls, or any mechanical systems. That means your project still requires a general contractor or construction team that can:

Install a foundation (frost-protected shallow foundation or traditional footing and stem wall). Assemble the SIP panels on the foundation in the correct sequence. Seal all panel seams with adhesive and tape (critical for air tightness). Integrate mechanical systems (HVAC, plumbing, electrical) into and through the panels. Add the final roofing, cladding, windows, doors, and interior finishes.

Extreme Panel's pre-designed packages include triple-pane windows (high-efficiency glazing), heat pump HVAC integration, and heat-recovery ventilation systems achieving 80 percent recovery efficiency. Those components are specified in the package design, which means the SIP kit is engineered to accommodate them, but the windows, doors, and mechanical equipment are typically sourced and installed separately by the contractor. Some packages include rough-in for solar panels and EV charging infrastructure, reflecting a design bias toward net-zero-capable homes.

Assembly timeline for a SIP kit is compressed compared to stick framing. A contractor with SIP experience can often erect the entire panel structure, seal seams, and achieve a weathertight envelope in 2 to 4 weeks. The critical bottleneck is design and manufacturing: if you order a custom SIP kit, allow 8 to 12 weeks from order to delivery. Pre-designed kits are faster: ordering and delivery might be 6 to 8 weeks. On-site assembly, once the panels arrive and the foundation is ready, is the shortest phase of the project.

One practical consideration with SIPs is the need for skilled assembly. SIP panels must be installed in a specific sequence, seams must be sealed properly for the insulation and air-sealing benefits to materialize, and mechanical systems must be routed carefully so they don't create thermal breaks or bypass the insulation. A contractor new to SIPs who treats them like a stick-frame build will lose performance. Extreme Panel provides installation manuals, training videos, and technical support, but the contractor or builder needs to be motivated to learn. That said, SIPs are not obscure: many regional builders now have SIP experience, and the assembly logic is learnable by any competent framing crew.

Cost comparison: a SIP shell typically costs 20 to 40 percent more than the framing-only cost of an equivalent stick-frame house. The tradeoff is that you save labor on framing (SIPs are faster to install than stick framing), you save on exterior insulation (the foam core replaces blown-in batts and exterior rigid foam), and you gain energy performance. For ADU applications where energy efficiency matters and the project timeline is a constraint, that tradeoff often makes sense. For a cost-minimized approach, stick framing is still cheaper.

Extreme Panel Technologiesworks with builders and homeowners directly, offering both pre-designed kits and custom panel design services. The company maintains an installation support network and can connect you with contractors experienced in SIP assembly if you need guidance. The pre-designed models are priced competitively and ship within a known timeframe, which appeals to builders and developers looking for predictability.

Extreme Panel Technologies is a strong fit if you're building an ADU and want superior insulation performance, a predictable assembly timeline, and a well-proven building system. The pre-designed Astro or Vega models fit many ADU footprints, and the energy performance is meaningfully better than stick frame. If you're in a climate with significant heating or cooling loads, or if your site or zoning calls for a high-efficiency building, the SIP approach delivers that. Choose Extreme Panel if you're comfortable with a slightly higher material cost in exchange for lower operating costs and a faster on-site build.