Engineered for Performance. Designed for Builders.

At Foundation Vehicles, we set out to create the most thermally efficient, builder-friendly composite camper bodies in the industry. After years of R&D, field testing, and collaboration with vehicle OEMs, we developed a system that dramatically improves insulation, structural integrity, and upfitting efficiency.

Advanced Composite Panels

The proprietary panels used feature a lightweight 1.5” closed-cell PIR foam core bonded to high-strength fiberglass skins. This formulation outperforms traditional EPS and PET-based solutions in thermal resistance, strength-to-weight ratio, and long-term durability.

  • Core: Rigid PIR foam (higher R-value, better fire resistance)

  • Skins: Proprietary fiberglass layup with gelcoat finish

  • Bonding: Vacuum-laminated for consistent flatness and adhesion

  • Weight: Starting at ~1000 lbs per van body

  • Premium, insulated materials

  • High-impact resistance

  • Efficient climate control

  • Made in the USA

Comparing Insulation Cores: PIR vs EPS vs PET

In the upfitting industry, insulation performance directly impacts customer comfort and build quality.

EPS (expanded polystyrene, aka Styrofoam) is inexpensive and lightweight but suffers from low R-value and poor moisture resistance. It compresses easily, causing issues when mounting windows, doors, or vents, and panels often warp or appear wavy due to inconsistent manufacturing methods. EPS, also has a low melting point and is susceptible to mold when exposed to moisture. It’s insulation performance significantly decreases in high-temperature environments, making it a poor choice for hot climates. While some competitors market their panel’s ability to withstand impact, we focused on improving structural integrity and insulation value—because customers don’t drive and use their RVs by hitting them with hammers (but just because we can, our panels are 40% stronger than the next best, so if you really need to, it is not a problem!).

PET (polyethylene terephthalate) offers moderate insulation and is more environmentally friendly, but it is extremely heavy and lacks the rigidity needed for long-term structural performance. The added weight reduces vehicle payload and fuel efficiency—critical concerns in upfitting. PET is also more flexible than PIR, which can lead to deflection or bowing in large panels, complicating cabinetry alignment and interior framing. While it's often praised for its recyclability, PET's inconsistent quality due to recycled input sources can lead to variable strength and finish. Additionally, its lower R-value compared to PIR makes it less effective in both extreme cold and heat.

PIR (polyisocyanurate), found in the panels used by Foundation, delivers the highest R-values, greatest rigidity, and Class 1 fire ratings. It’s lighter than PET, stronger than EPS, and specifically engineered to hold up to repeated thermal cycling and rugged use—ideal for high-performance four-season applications. PIR offers excellent dimensional stability, meaning it resists compression, expansion, and warping under load, temperature changes, and humidity. The closed-cell structure eliminates water absorption, preventing rot and degradation over time. Unlike EPS and PET, PIR maintains its thermal performance for the life of the vehicle, ensuring consistent comfort in both hot and cold environments. The material is engineered for strength without weight penalties, providing a high strength-to-weight ratio that supports interior build-outs without sacrificing payload.

Patented Aluminum-Polymer Extrusion

The patented 2-piece corner extrusion system was developed to reduce thermal bridging, increase rigidity, and allow cleaner transitions between body panels. 

  • Material: Aircraft-grade aluminum and structural polymer

  • Design: Interior/exterior split with thermal break

  • Benefits: No cold spots, no metal bridging, fast panel alignment

Extrusion Comparison: Foundation vs Pultrusions

Most composite camper bodies on the market rely on fiberglass pultrusions for structural joints. Pultrusions are inexpensive and simple to manufacture but introduce several key drawbacks: they are brittle under stress, prone to cracking at corners, and highly conductive. The single-material construction of pultrusions allows thermal conduction across the joint, with no true thermal break.

Other companies use a two-piece pultrusion system where one piece is glued from the outside and one from the inside. While this creates a nominal seam, it offers minimal structural strength and makes assembly more difficult and time consuming. The single-material construction of pultrusions also allows thermal conduction across the joint, with no true thermal break.

In contrast, the patented aluminum-polymer extrusion used by Foundation was designed from the ground up for thermal performance. The interior/exterior split eliminates metal-to-metal contact, preventing cold spots. Our system provides superior rigidity, and the highest performing thermal break.

Torsion-Reduction Subframe

To address the natural flex and torsion inherent in a chassis, a torsion-reduction subframe was  developed in conjunction with Mercedes-Benz. This subframe isolates the composite camper body from chassis twist, reducing stress on the structure and preventing long-term damage like panel separation or seal fatigue. It also provides a flat, square, and consistent foundation for mounting, which ensures seamless integration and consistent upfitting. This system is essential for maintaining alignment across doors, windows, cabinetry, and other internal components along with body fatigue that can lead to cracks and leaking—especially during off-road use or uneven loading conditions.

OEM Integration & Certification

We have worked closely with Mercedes-Benz to align our designs with OEM guidelines. Foundation Vehicles is in the process of becoming an official Mercedes-Benz Certified Upfitter.

  • Sprinter-specific platform geometries (144, 170, 170ext)

  • Alignment with FMVSS, OEM mounting, and safety guidelines

  • Mercedes upfitter application and testing approval underway

Built to Accelerate Your Business

Whether you're building 1 unit or scaling to 100+ per year, our platform helps you:

  • Provide more space in the same overall length, on a proven chassis

  • Deliver a better 4-season product

  • Significantly reduce build time

  • Offer customers a cleaner, stronger build

Let your next vehicle start with a true foundation.

foundationvehicles.com | @foundationvehicles