What humidity level is maintained inside a fireproof filing cabinet?

In normal non-fire conditions, a fireproof filing cabinet does not actively regulate humidity — the interior is roughly at ambient room humidity, since the cabinet is not airtight in normal operation. The insulating material inside the cabinet walls can slightly buffer temperature and humidity fluctuations, but the effect is minor. For long-term archival document storage, supplementing with silica gel desiccant packets inside the drawers absorbs excess moisture and maintains a drier interior. The key humidity concern for fire protection cabinets is the moisture that the insulating material releases during a fire event — this steam is intentional and part of the fire-protection mechanism. FindOfficeFurniture.com — call 888-719-4960 for archival-appropriate storage options.