Specifying IP ratings for steam-heavy bathrooms

IP ratings look like arbitrary numbers until you need one. Then the difference between IP44 and IP54 becomes the difference between a mirror that survives a wet room and one that fails its warranty in a year. Here is how to read them, and how to specify the right one.

What the two digits mean

The first digit is protection against solids — dust and debris. The second is protection against water. For mirrors, the second digit does the work: a 4 resists splashing water from any direction; a 5 resists low-pressure jets. Most domestic bathrooms are comfortable at IP44. Spas, gyms, and steam rooms move up to IP54 because they live in water, not near it.

The difference between IP44 and IP54 is the difference between a mirror near water and one that lives in it.

Buyer’s Desk

Write it down

The mistake is leaving the rating implied. Put it in the purchase order, in the line-item description, and on the approved sample’s tag. A rating you assumed is a rating no one is contractually responsible for. A rating you wrote down is a specification we build to — every unit, every batch.