Upfit a GM cargo van in this order: flooring, partition, shelving, roof rack, electrical. Each stage sits on top of the last, and doing them out of order means pulling parts back out. Before any of it, check your payload — a full steel shelving and rack package can consume several hundred pounds of a van's rated capacity before you load a single tool.
The Chevy Express and GMC Savana are unusually good vans to upfit because the body has changed so little for so long. A shelving unit designed for a 2010 Express generally fits a current one, which means a deep aftermarket and easy sourcing. Start from van and commercial vehicle parts for your Express or Savana and work through the stages below.
Parts and tools you'll need
- Flooring kit sized to your wheelbase — see GM van and commercial parts
- Partition or bulkhead, shelving modules and cargo restraint — browse interior accessories
- Ladder rack, roof crossbars, and exterior hardware — browse exterior accessories
- A rivet gun, a step drill, a torque wrench, and self-tapping fasteners rated for the panel thickness
How much weight can a GM cargo van actually carry?
More than most people assume, but the upfit eats into it. A 2025 Express Cargo 2500 carries an 8,600-pound GVWR against a curb weight around 5,261 pounds, which leaves a maximum payload figure in the neighborhood of 3,280 pounds depending on configuration. A 3500 goes higher. Every pound of shelving comes out of that number.
| Spec | 2025 Express Cargo 2500 (regular length) | Notes |
|---|---|---|
| Wheelbase | 135.0 in | Extended body versions exist — confirm yours before ordering shelving |
| Cargo volume | 239.4 cu ft | Extended bodies carry more; interior length is what shelving is sized to |
| GVWR | 8,600 lb | 3500 models are rated higher |
| Curb weight | Approx. 5,261 lb | Varies with options and engine |
| Max payload | Up to approx. 3,280 lb | Configuration-dependent — read the sticker on your own van |
| Base engine | 4.3L V6, 276 hp @ 5,200 rpm | A 6.6L V8 has been offered as an option |
| Transmission | 8-speed automatic | Earlier model years used 6-speed units |
| Max towing | Up to 10,000 lb | Requires the correct hitch and configuration |
Those figures describe a specific configuration. Your van's real numbers are on the certification label in the driver's door opening, which lists GVWR and the front and rear GAWR. Read them before you spec anything, because a fully loaded steel upfit plus a full fuel tank plus two people plus material can put a 2500 over its rear axle rating without ever looking full.
Safety note: weight distribution matters as much as total weight. Heavy shelving loaded high and far rearward makes the van handle badly in crosswinds and under braking. Put weight low and ahead of the rear axle wherever the job allows.
Why does flooring go in first?
Because everything else bolts through it. Shelving feet, partition brackets and tie-down anchors all land on the floor, and installing flooring afterward means removing all of it. Flooring also seals the factory floor pan from the water, salt and dropped fasteners that eat a work van from the inside.
Two approaches. Plywood is cheap, available anywhere, and easy to cut around the wheel wells and body ribs. It also absorbs moisture, splinters under repeated abuse, and needs sealed seams to survive a wet trade. Composite flooring costs more, comes cut to fit a specific van so there is no template work, resists moisture and chemicals, and weighs less — which matters when you are counting payload.
| Plywood | Composite | |
|---|---|---|
| Fit | Cut to fit — expect a template and an afternoon | Pre-cut for the specific van and wheelbase |
| Moisture | Absorbs water, needs sealing at every seam and edge | Does not absorb; joints designed to shed water |
| Weight | Heavier | Lighter, which returns payload |
| Damage resistance | Dents and splinters under dropped tools | Built for impact and abrasion |
| Cost | Lowest | Higher up front |
| Best for | Dry trades, short-term vans, tight budgets | Plumbing, HVAC, anything wet, long-term fleet use |
If you are building a van you will keep five years and work out of daily, composite is the better buy. If the van is a two-year stopgap or the cargo is dry and light, plywood is genuinely fine. This is one of the places where the cheap option is not a mistake.
Whichever you choose, add a floor mat or a rubber runner over it in the traffic path. Replacing a mat is cheaper than replacing a floor.
Do I need a partition or bulkhead?
If you carry anything heavy behind the seats, yes. A partition exists to keep cargo from entering the cab under braking or in a collision, and that is not a theoretical risk in a van where the load floor starts a few inches behind your shoulder.
Partition styles trade cab room against access. A flat solid bulkhead gives maximum protection and zero reach-through. A contoured or comfort partition steps back around the seats for more recline. A partition with a pass-through door lets you get into the cargo area without going outside, which matters in winter and in bad neighborhoods, at the cost of a hole in the barrier.
Solid steel is heaviest and strongest. Steel with a window keeps rearward visibility, which some drivers will not give up. Perforated and mesh designs split the difference on weight. Decide based on what you actually carry, not on what looks most secure.
Install the partition before shelving. It defines where the cargo area begins and it is the reference point for laying out everything behind it.
How do I lay out shelving in an Express or Savana?
Measure the interior, then decide what has to be reachable from the side door versus the rear doors. Shelving that blocks the side door on a van with a curb-side sliding door wastes the most useful access point on the vehicle.
- Measure interior length from the partition to the rear door opening, floor to ceiling height, and width at the wheel wells — the wheel well is the constraint, not the widest point.
- Confirm your roof height and wheelbase. Shelving is sold by van model and configuration, and a unit for an extended body will not drop into a regular one.
- Decide which side carries heavy stock. Put it on the driver's side ahead of the rear axle if the layout allows.
- Leave a clear aisle wide enough to actually walk, not the minimum the tape measure permits.
- Reserve floor space for the things that never fit on a shelf — a ladder, a compressor, a spool of wire.
- Mount shelving to the floor and to the van's factory body-mounting points where they exist, not only to sheet metal.
- Add drawer units for small parts. Open shelves scatter fasteners across the floor on the first hard stop.
- Fit cargo restraint — E-track, straps or nets — for anything not enclosed.
Steel shelving is durable and heavy. Aluminum and composite shelving costs more and gives payload back. On a 2500 running near its rating, the weight difference between a steel and an aluminum package can be the difference between legal and overloaded.
Before drilling anything, look up what is behind the panel. Fuel and brake lines, wiring harnesses and body reinforcements all run through areas that look like empty sheet metal from inside. GM publishes body builder manuals for the Express and Savana that show what is where, and they are worth reading before the drill comes out.
What should I know about ladder racks and roof loads?
Rack capacity and roof capacity are two different limits, and the lower one wins. A rack rated at several hundred pounds does not mean the van's roof structure is rated for that much, especially in motion where a ladder generates dynamic loads well above its static weight.
Check the rack manufacturer's published capacity for the specific model you are buying, and check GM's roof loading guidance for your van in the body builder manual for your model year. If the two disagree, use the lower figure. Do not assume a number based on what the rack looks like it could hold.
Mounting matters more than the rating. Clamp-on racks that grip the rain gutter or drip rail install without drilling and are removable, which is worth something at resale. Bolt-through racks anchor into the roof structure and are more secure for heavy daily ladder work, at the cost of holes that must be sealed properly. Seal them properly or you will find the leak the following spring.
Practical additions: a drop-down or clamp-style ladder rack saves your back and your paint, roller ends on the rear crossbar make loading a single-person job, and a bulkhead-mounted conduit carrier keeps long stock off the shelves. Browse ladder racks and exterior accessories and compare mounting styles before you compare prices.
What electrical provisions does a GM van have for upfitters?
More than most owners realize. GM builds specific upfitter provisions into the Express and Savana and identifies them with RPO codes on the vehicle's option label, so you can find out what your van already has before you start splicing.
| RPO code | What GM calls it | What it means for you |
|---|---|---|
| 9L7 | Accessory wiring junction block | A factory point to feed upfit equipment instead of tapping the harness |
| KI4 | 110-volt electrical receptacle, instrument panel | Household outlet in the cab for chargers and small tools |
| UTN | Provisions for upfitter control and monitoring | Dedicated circuits intended for aftermarket equipment |
| ENC | Auxiliary heater plumbing and wiring provisions | Groundwork for an auxiliary heat installation |
Find your RPO label — commonly in the glovebox or on an interior panel — and read the codes before ordering wiring parts. Using a factory junction block instead of a scotch-lock into the wrong circuit is the single biggest quality difference between a professional upfit and a homemade one.
Beyond the factory provisions, plan power like an electrician. Fuse every added circuit as close to the source as physically possible. Use automotive-grade sealed connectors, not household wire nuts. Ground to a clean, paint-free chassis point with a proper ring terminal. And if you are running an inverter, a fridge or anything that draws with the engine off, add a second battery with an isolator rather than draining the starting battery.
The same electrical discipline applies to any lighting you add — cargo lamps, work lights, beacons. Our writeup on LED conversions and vehicle circuit monitoring on GM vehicles covers why load-sensitive circuits behave the way they do when you change what is plugged into them.
What else is worth adding?
Interior lighting is the highest-value cheap upgrade in a work van. The factory cargo lamp is one bulb in a large dark box. LED strips down each side, wired to the door switch and to a manual override, change how the van works after dark.
After that, in rough order of usefulness: door and lock security hardware, because a work van is a toolbox with wheels; wall liners to stop cargo from denting body panels from inside; a rear step or bumper step for repeated entry; and a backup camera if the van predates one, since a partition eliminates rearward vision entirely.
Sound and thermal insulation is the underrated one. An empty steel box is loud and it swings 40 degrees between morning and afternoon. Insulation applied before the flooring and wall liners makes the van meaningfully more pleasant to spend eight hours in.
Fit interior hardware and organizers from interior accessories once the structural upfit is done and you know what space is left.
Does upfit gear fit across model years?
Largely yes, and it is the Express and Savana's best feature as a work platform. The current body has been in production with minimal dimensional change for a very long time, so shelving, partitions and racks tend to carry across a wide span of years.
The exceptions are worth knowing. Body length and wheelbase change everything about shelving fit — a regular-length and an extended van are different vehicles for upfit purposes. Passenger van conversions have floor structures cargo vans do not. And anything that bolts to the roof or the doors can be affected by option content and by the presence of factory racks or windows.
The most reliable approach: measure your own van rather than trusting a year range on a listing. Interior length from partition to rear door, height at the wall and at the center, and width at the narrowest point between wheel wells. Those three numbers settle almost every fitment question before you order.
What to check before you order
- Read the certification label in the driver's door opening for GVWR and axle ratings, then subtract your planned upfit weight.
- Confirm regular versus extended body and your wheelbase before ordering flooring or shelving.
- Measure interior length, height and width at the wheel wells yourself.
- Read the RPO codes on your option label to find out which electrical provisions you already have.
- Check the roof load figure in GM's body builder manual for your model year against the rack's rating, and use the lower number.
- Plan the install order: flooring, partition, shelving, rack, electrical. Do not reverse it.
- Decide steel versus aluminum shelving based on your remaining payload, not on price alone.
Frequently Asked Questions
What order should I upfit a cargo van in?
Flooring, partition, shelving, roof rack, electrical. Each stage sits on top of the last — shelving feet, partition brackets and tie-down anchors all bolt through the floor, so installing flooring afterward means pulling everything back out.
How much payload does an upfit use up?
A full steel shelving and rack package can consume several hundred pounds before you load a single tool. A 2025 Express Cargo 2500 has an 8,600 lb GVWR against roughly 5,261 lb curb weight, leaving around 3,280 lb depending on configuration — but read the certification label on your own van, since a loaded steel upfit plus fuel, two people and material can exceed the rear axle rating without the van looking full.
Plywood or composite flooring?
Composite if you will keep the van five years and work out of it daily — it comes pre-cut, resists moisture and chemicals, and weighs less, which returns payload. Plywood is genuinely fine for a dry trade, a short-term van or a tight budget. This is one place where the cheap option is not a mistake.
Do I need a partition in a cargo van?
If you carry anything heavy behind the seats, yes. It exists to stop cargo entering the cab under braking or in a collision, which is not theoretical in a van where the load floor starts a few inches behind your shoulder. Install it before shelving — it is the reference point for everything behind it.
How much weight can a van roof hold?
Rack capacity and roof capacity are two different limits, and the lower one wins. Check the rack manufacturer's rating for that specific model against GM's roof loading guidance in the body builder manual for your model year, and use the lower figure. A ladder in motion generates dynamic loads well above its static weight.
Should I drill into the van body for shelving?
Only after checking what is behind the panel. Fuel and brake lines, wiring harnesses and body reinforcements run through areas that look like empty sheet metal from inside. GM publishes body builder manuals for the Express and Savana showing what is where — read one before the drill comes out.
What electrical provisions does my van already have?
Check the RPO codes on your option label. 9L7 is an accessory wiring junction block, KI4 a 110-volt receptacle in the instrument panel, UTN provisions for upfitter control and monitoring, and ENC auxiliary heater plumbing and wiring. Using a factory junction block instead of a scotch-lock is the biggest quality difference between a professional upfit and a homemade one.
Steel or aluminium shelving?
Depends on your remaining payload, not on price. Steel is durable and heavy; aluminium and composite cost more and give payload back. On a 2500 running near its rating, that weight difference can be the difference between legal and overloaded.
Will shelving from an older Express fit a newer one?
Usually. The body has changed very little for a long time, which is the platform's best feature as a work van. The exceptions are body length and wheelbase — a regular-length and an extended van are different vehicles for upfit purposes. Measure your own van rather than trusting a year range on a listing.
Where should heavy items go in the van?
Low and ahead of the rear axle wherever the layout allows. Weight distribution matters as much as total weight — heavy shelving loaded high and far rearward makes the van handle badly in crosswinds and under braking.
A Note on Sourcing
Weights, dimensions, GVWR and payload figures are GM published specifications for a stated configuration — a 2025 Express Cargo 2500 of regular length. They are included to show the scale of the numbers. The certification label in your driver's door opening carries your van's actual GVWR and front and rear axle ratings, and that is what governs.
The RPO codes for upfitter provisions — 9L7, KI4, UTN and ENC — are GM's own option codes, readable from the label in your glovebox or on an interior panel.
Roof load limits are deliberately not given as a number. Rack capacity and vehicle roof capacity are separate limits set by different parties, and the correct figure for your van is in GM's body builder manual for your model year. Where the two disagree, the lower one is the real limit.
The install order and the material recommendations are our own. We sell upfit parts, and the position stated here is that plywood flooring is a perfectly reasonable choice for a dry trade or a short-term van rather than something to be talked out of.
More parts and accessory guides are collected in our GM parts and accessories library, and the wear-item side of running these vans is covered in our Express and Savana wear parts guide.
Build the van in one place
Everything in this guide, in one place. Flooring, partitions, shelving, racks and the hardware to mount them are in GM van and commercial vehicle parts, with the rest in interior accessories and exterior accessories. Measure your van and check its payload sticker before you order.