Digits and Hyphens in Inspection Reports

by Nick GromickoCMI®, and Kate Tarasenko

When writing inspection reports, it’s sometimes difficult to decide whether to write numbers using numerals or as spelled-out words. The rule of thumb for grammarians is that numbers as measurements and percentages should be rendered as digits, and numbers describing amounts and as length of time should be rendered as words, particularly when referring to single-digit numbers (amounts under 10), or where the use of double-digit numbers may cause visual confusion for the reader.
For example:
  • Inspections should be performed no less than every two years for one- and two-family dwellings.
  • Expect to use eight 5-pound buckets of compound.
  • There should be a 6-foot turnaround at each entrance, which should be at least 3 feet wide.
  • The slope of the grade should be at least 5%.
  • There is a bend in the rail of 90 degrees.
  • It's 90º F out today.
  • Use a couple of 2x4s for that step repair.
  • It's a two-story building.
  • The occupants live on the second floor.
  • The nails should be spaced 1 inch apart.
  • There is only one family living in that apartment complex.
  • Each component weighs 2 pounds, 7 ounces.
  • The clearance should be a minimum of 6 feet, 8 inches.
  • Some clearances require only 6-1/2 feet.
  • Use a 3/4-inch nail.

But this is okay:

  • The structure houses 24 businesses.
    (Note the double-digit amount over 10 rendered as digits, especially because there are no other numbers to compete with it.)
  • You will need twelve 10-inch shims.
    (Best to spell out 12 to avoid confusion with "10-inch" right next to it.)

In addition to conforming to the basic rules of English, the numerals-versus-words distinction helps to maintain visual uniformity, and it makes information recognition easier for inspection report readers.
Also, note the use of hyphens with numbers.  In adjective phrases that modify or describe the nouns they precede, the phrases should be hyphenated, like this:
  • two-family dwelling: “two-family” describes the type of dwelling.
  • 5-gallon bucket:  “5-gallon” describes the measured capacity of the bucket.
  • 6-foot turnaround:  “6-foot” describes the measured space for the turnaround.

Otherwise, no hyphenation for the numbers is needed, like this:
  • Two families live in the dwelling.
  • The box holds 20 pounds of nails 
  • The cast-iron tub rests on six feet.