Your van's structure is the skeleton that everything else hangs on. Get this right and the rest of your build goes smoothly. Get it wrong and you'll be fighting problems for the life of the van. The good news is that it's not complicated - it just takes some planning.
Think of a van build's structure in layers, from the outside in:
Layer 1: The van's metal body - Already there. You're working with (not against) the existing structure.
Layer 2: Insulation - Goes against or between the van's metal ribs. Keeps heat in/out and prevents condensation.
Layer 3: Framing - Wood furring strips or metal channels that give you something to attach your walls and ceiling to.
Layer 4: Finish surfaces - Your wall panels, ceiling panels, and flooring. What you actually see and touch.
Running through all of this: your wiring and plumbing, which need to be routed before you close up walls and ceilings. This is why build order matters so much - once the walls are up, adding a wire run means tearing things apart.
Critical point: Plan your electrical and plumbing runs before you start closing up walls. Know where your lights, outlets, switches, and water lines will go. You don't need to run them all at once, but you need to know where they'll go so you can leave access or run conduit.
You need some kind of framework to attach your interior finish materials to. The van's metal body has ribs and mounting points, but you can't just screw paneling directly to the metal and call it done. You need a gap for insulation and a flat surface for your finish materials.
For most DIY builders: Wood furring strips are the way to go. They're cheap, forgiving, and work great. 80/20 is awesome but is best suited for high-end builds where the extra cost and complexity are justified. Don't let Instagram builds convince you that you need aluminum extrusion for a perfectly functional van.
Your floor is the foundation of everything. It needs to be level, strong enough to support your furniture and you walking on it, insulated, and moisture-resistant. Most van builders use a layered approach:
Bottom: Vapor barrier or reflective material directly on the metal floor
Middle: Rigid foam insulation (XPS or polyiso) cut to fit between the floor ribs
Subfloor: 1/2" or 3/4" plywood screwed or bolted to the van's existing floor mounting points
Top: Finish flooring - vinyl plank, laminate, or whatever you choose
Once your insulation and framing are in place, you need to cover them with finish panels. There are several good options, each with different tradeoffs:
The classic van build look. Cedar and pine are most common. Looks warm and beautiful, but adds weight and cost. Cedar smells great and is naturally moisture-resistant. Pine is cheaper but should be sealed.
Cost: $2-6 per sq ft depending on wood type
Thin, lightweight plywood that can be bent to follow curves. Very popular for ceilings especially. Can be stained, painted, or left natural. One of the lightest and cheapest options.
Cost: $0.50-1.50 per sq ft
Waterproof, lightweight, easy to clean. Great for kitchen and bathroom areas. Can look a bit "plasticky" but modern options are much better. Won't rot or absorb moisture.
Cost: $1-3 per sq ft
Foam board wrapped in upholstery fabric or vinyl. Looks great, hides imperfections, and provides a bit of sound dampening. Common in professional builds. More work to install but very forgiving.
Cost: $2-5 per sq ft including fabric
The most common mistake: People close up walls before running all their wiring. Then they realize they forgot a wire run for a light or outlet, and they have to tear panels back off. Plan all your electrical and plumbing before you start closing things up. Even if you're not installing them yet, at least run empty conduit or leave access panels.
For most first-time builders: Keep it simple. Wood furring strips for framing, Thinsulate or foam board for insulation, 1/2" plywood subfloor with LVP on top, and luan or tongue-and-groove for walls and ceiling. This combination is proven, affordable, and forgiving of mistakes.
Don't overcomplicate your structure. The fanciest wall panels in the world won't make your van more comfortable - but a well-insulated, properly ventilated, and thoughtfully wired van will. Focus on getting the fundamentals right and spend your energy on the systems that actually affect daily living.
Your van's structure should be invisible - you shouldn't think about it once it's done. That means doing it right the first time with materials that won't cause problems down the road.