Short answer: about 34 to 37 sheets of 4x8 EPS for the walls, end wall and ceiling of a 40 ft standard container, plus inserts for the corrugations. Our standard 40 ft kit uses 39 flat sheets and 152 ridge inserts.
Do the math
Inside a 40 ft standard container is roughly 39 ft 5 in long, 7 ft 8 in wide and 7 ft 10 in tall. Check yours; a high cube is about a foot taller.
- Side walls: 2 x 39.4 x 7.8 ft, about 615 sq ft
- End wall: 7.7 x 7.8 ft, about 60 sq ft (the door end is usually framed separately)
- Ceiling: 39.4 x 7.7 ft, about 303 sq ft
That's about 980 sq ft. One 4x8 sheet covers 32 sq ft, so 980 / 32 is about 31 sheets. Add 10 to 20 percent for cuts and openings and you land at about 34 to 37 sheets. Doing the floor too? Add about 10 more. Subtract windows and doors you're cutting in.
Why flat sheets alone leave gaps
Container walls are corrugated. Flat board only touches the high points and leaves an open channel behind every ridge. Ridge inserts fill those channels first, so the sheets go on flat and tight.
High cube?
Add roughly 2 to 3 sheets for the taller walls.
Thickness
Thicker foam insulates more but takes up floor space. Our kits use 2.5 inch sheets over the inserts.
Typical R-value
| Density | R per inch | 2.5 in sheet |
|---|---|---|
| 1.0 lb EPS | R-3.9 | about R-9.8 |
| 1.5 lb EPS | R-4.2 | about R-10.5 |
| 2.0 lb EPS | R-4.4 | about R-11.0 |
Typical values at 75°F from the Rapid Insulation EPS data sheet (REV004). Ask us for the full sheet.
Get it cut
We cut container kits for 20 and 40 ft, standard and high cube, in American Fork, Utah. Send a photo of one ridge with a tape across it and we'll check the fit. See our shipping container insulation kits.