Guides
Fireproof Safe for Documents: UL Ratings That Actually Matter
A fireproof safe for documents is only as good as its UL 72 class. Compare paper and media safes, endurance times and the one limit they all share.
What to take away
- UL 72 is the US test standard for record protection equipment. The class number is the maximum internal temperature in Fahrenheit, not a grade of quality.
- Paper tolerates about 350°F, so Class 350 is the paper class. Film, tape and drives need Class 125 or Class 150.
- A Canadian ULC mark comes from a different organization and is not a UL 72 listing. US insurers read the UL file number.
- No container is fireproof. Match the rating to your fire risk and keep copies off site.
What UL 72 actually tests
UL 72 is titled Tests for Fire Resistance of Record Protection Equipment. Underwriters Laboratories writes it, and US manufacturers list containers against it. A listed container carries a class number, and that number is not a score out of anything. It is the ceiling the test allowed for air inside the container, in degrees Fahrenheit.
Common classes are 350, 150, 125 and 100. The listing also names an endurance time: half an hour, one hour, two hours or four hours. A label reading "UL 72 Class 350, one hour" means the interior stayed below 350°F across a full hour in the furnace. Paper scorches above 350°F, which is where that class comes from.
The criteria that separate paper safes from media safes
Paper safes vs media safes
Paper safe, Class 350
- Internal ceiling
- 350°F
- Endurance
- Half hour to two hours
- Material
- Paper, card, some textiles
- Impact and explosion steps
- Part of the listing
- Cost
- Roughly $200 to $900, illustrative
Media safe, Class 125 or 150
- Internal ceiling
- 125°F to 150°F
- Endurance
- Usually one hour
- Material
- Film, tape, negatives, drives
- Impact and explosion steps
- Part of the listing
- Cost
- Roughly $400 to $2,000, illustrative
Unrated fire chest
- Internal ceiling
- No tested ceiling
- Endurance
- A claim of 20 to 30 minutes
- Material
- Paper, in mild fires only
- Impact and explosion steps
- Usually absent
- Cost
- The lowest price on the shelf
The first decision is the material, not the price. Negatives, magnetic tape and hard drives lose data at temperatures well below paper's limit, so a Class 350 box that passes every paper test will still cook a drive. NFPA 232 treats records protection as a system of storage, detection and suppression, which is worth a read before you spend.
Paper vs Media vs Unrated
Paper safe, Class 350
- Internal ceiling
- 350°F
- Endurance
- Half hour to two hours
- Material
- Paper, card, textiles
- Impact and explosion steps
- Part of listing
- Cost
- $200 to $900
Media safe, Class 125/150
- Internal ceiling
- 125°F to 150°F
- Endurance
- Usually one hour
- Material
- Film, tape, negatives, drives
- Impact and explosion steps
- Part of listing
- Cost
- $400 to $2,000
Unrated fire chest
- Internal ceiling
- No tested ceiling
- Endurance
- Claim of 20 to 30 minutes
- Material
- Paper, mild fires only
- Impact and explosion steps
- Usually absent
- Cost
- Lowest price on shelf
Space is the next surprise. A container advertised at one cubic foot holds fewer letter folders than the outside suggests, and collections grow. Settle your numbering and naming systems before you buy, so the container matches the catalogue you keep.
Option by option: three classes of rated container
Three classes of rated container
- UL 72 Class 350 paper safe. Insulated steel, rated from half an hour to two hours, sold through office stores and safe dealers. Insulated filing cabinets sit in the same class and take hanging folders, which suits paper archives better than a deep chest.
- UL 72 Class 125 or 150 media safe. Thicker insulation, a tighter seal, a shorter rating. More money per cubic foot and less room inside. Choose it when film, tape or drives are the priority.
- Unrated fire chest with a manufacturer's claim. Light and cheap, and the label usually names no standard. Treat the claim as a claim.
Where each one wins
Paper safe. Right for deeds, letters, certificates and paper photo albums, kept where a fire crew can reach the room. One hour at Class 350 is the usual choice for a household collection of paper.
Media safe. Right when the negatives and the drives are the only copies. If the safe and the closet have to agree on one condition, choosing one shared condition is the decision that matters more than the box.
Unrated chest. Right when the alternative is a shoebox on a shelf, or when the documents have already been scanned and stored off site. A first step, not a destination.
What none of them solve
All three protect an object inside the house while the fire is in the house. None survive a fire that takes the room and the floor above, and none help if the container sits in the hottest corner of a garage or basement.
Water is the second problem: a hot container hosed down traps moisture for weeks.
Start with inspecting the building, not the boxes, and take the same order here. USFA guidance on home fires covers escape planning and the safe storage of documents in the same place.
A safe is not fireproof. It buys delay. The delay is worth the money only when the originals also exist somewhere else.
The limitation all three share is that they protect the object, not the information. A copy kept off site is the only thing that survives the loss of the building.
