20ft vs 40ft Container Shelter: Which Size to Buy
Container shelters come in a handful of standard sizes built around shipping-container footprints. Pick too small and your equipment won't fit; pick too big and you overpay and over-build. This guide breaks down the three common sizes — what each one covers, what fits under it, and how to choose — so you buy once and buy right.
How container shelter sizing works
A container shelter is a fabric-and-steel roof that spans the gap between two shipping containers, which act as the walls and anchor. So the "size" describes the roof span, and it's tied directly to the containers you're spanning between. Suppliers offer three main configurations — one built for 20 ft containers and two for 40 ft containers (Dry Box USA).
The three common sizes
| Size (W × L) | Coverage | Peak height | Spans between |
|---|---|---|---|
| 20 × 20 ft | ~400 sq ft | ~6.5 ft sides | Two 20 ft containers |
| 20 × 40 ft | 800 sq ft | ~6.5 ft sides | Two 40 ft containers |
| 40 × 40 ft | ~1,600 sq ft | up to ~15 ft | Two 40 ft containers, wide span |
The 20 × 40 configuration is the volume seller: it delivers 800 sq ft of covered space with a practical 6.5 ft side clearance, sized for standard containers and most commercial vehicles and equipment (Kit Buildings). The 40 × 40 is the heavy-duty step up — a wider clear span with a much higher peak (up to ~15 ft) for large machinery and taller loads (Kit Buildings).
What actually fits
- 20 × 20 — a workshop bay, small equipment, ATVs, a single small vehicle. Tightest and cheapest.
- 20 × 40 — vehicles, an RV or boat, general bulk storage. The all-round choice for most buyers.
- 40 × 40 — large machinery, multiple vehicles side by side, or anything tall — the extra peak height is the reason to go big.
Price: bigger costs more — but check the frame
Kit price rises with size and with fabric weight and steel gauge, so a heavy 40×40 costs well more than an entry 20×20. Published listings show these kits use serious materials — e.g. 21 oz / 610 gsm PVC covers on galvanized steel (Mytee Products) — and heavier specs raise the price within any given size. Don't compare sizes on footprint alone; a lighter 40×40 can cost less than a heavy-duty 20×40 while lasting less time. For the full cost picture including containers, anchors, and install, see our cost breakdown.
How to choose in 3 steps
- 1. Measure your biggest item — length, width, and especially height. Add clearance to move around it.
- 2. Match the container length you have (or will buy) — 20 ft containers → 20×20; 40 ft containers → 20×40 or 40×40.
- 3. Go one size up if you're between — covered space always gets used, and re-buying a bigger kit later costs far more than sizing up now.
FAQ
What's the most popular size?
The 20 × 40 ft kit — 800 sq ft, standard 6.5 ft clearance, and it spans between two common 40 ft containers. It suits most vehicle and general-storage needs.
Do I need tall containers for a high shelter?
No — the peak height comes from the arch. The 40×40 frame reaches up to ~15 ft at the center regardless of container height. Choose it when you store tall equipment.
Can I extend a shelter later?
Some systems allow it, but retrofitting is rarely as clean or cheap as buying the right size upfront. Size for what you'll need in a few years, not just today.
Sources: Dry Box USA, Kit Buildings, and Mytee Products (linked inline). Coverage and clearance figures come from manufacturer listings; sizes and specs vary by supplier — confirm the exact dimensions and materials before buying.