It’s not unusual for husbands and wives to work together in small, family-owned businesses in the plumbing and drain cleaning fields. The division of labor typically shakes out with the husband working in the field while the wife manages the office and handles things like invoicing, accounting and miscellaneous paperwork.

But things are a little different at Pipeshield in Downingtown, Pennsylvania, where Sonya Vasile and her husband, Jaco, buck that stereotypical...