Washington Residential Service (PL04) Contractor License

The Residential Service (PL04) Contractor License allows you to:

  • Perform the following work on single-family dwellings and duplexes only:
    • Service, repair, or replace:
      • Previously existing fixtures, piping, and fittings that are outside the interior wall or above the floor, often, in a like-in-kind manner
  • Perform plumbing work as needed to:
    • Perform drain cleaning
    • Perform leak repairs on:
      • Any pipe, fitting, or fixture from the leak to the next serviceable connection
  • Supervise plumber trainees provided:
    • The trainees have been supervised by an appropriate journey level or specialty plumber for the trainees' first two thousand hours of training

A residential service plumber MAY NOT perform plumbing for new construction of any kind.

How to Get the Residential Service (PL04) Contractor’s License in Washington?

  1. Have experience as a Plumber Trainee. If you don’t have experience as a Plumber Trainee, meet the following requirements and apply for a Plumbing Trainee certificate:
    • Be at least 16 years old
    • Work under the supervision of a journey level or certified plumber
    • Take the 8 hours of plumbing code and 4 hours of electrical classes in two years
  2. Fill out and complete anAffidavit of Experience to report the supervised work hours as a plumber trainee
  3. Meet the required experience or education depending on the license applying for:
    • Residential Service (PL04): 4,000 hours as a plumber trainee under the supervision of a Journey Level, Residential or Residential Service plumber
  4. Fill out and notarize an Application for Contractor License
  5. Complete and obtain a Surety Bond or Assigned Savings Account
  6. Get a Certificate of Liability Insurance
  7. Choose a designated plumber to hold the valid plumber certificate. The designated plumber can be another person or the applicant, depending on whether they are applying as a business or as a sole proprietor
  8. Meet the following educational requirements and apply for the plumber examination with PSI©:
    • Residential Service (PL04) - 24 hours of continuing education, including:
      • 12 hours of Uniform Plumbing Code
      • 4 hours of Industry-Related Electrical
      • 8 hours in any Code, Industry-Related Electrical, or Industry-Related Plumbing area
  9. Refer to the PSI© Plumbing Examinations Candidate Information Bulletin, for more information on the test locations, subjects and books to prepare for the exam
  10. Submit the completed documents to:
    Washington State Department of Labor & Industries
    Plumber Certification
    PO Box 44470
    Olympia WA 98504-4470

Washington Residential Service (PL04) Contractor License Exam Prep Course

Washington Residential Service (PL04) Contractor License Exam

Below is all the information related to the trade exam, including the official reference list.

Washington Residential Service (PL04) Contractor Trade Exam

  • Testing Method: Computer-based testing
  • Testing Company: PSI©
  • Number of Questions: 65
  • Types of Questions: Multiple choice
  • Time Allowed: 90 Minutes
  • Minimum Passing Score: 70%
  • Subjects Involved:
    • Gas and Vacuum Systems
    • Pump Specialty
    • Medical Gas
    • Drain Cleaning
    • Leak Repairs on:
      • Pipe
      • Fitting
      • Fixture
  • PSI© Residential Service (PL04) Official Content Outline

Candidates must apply for eligibility with the Department before being allowed to take the examination. Please note that this is a closed-book examination.

Washington Residential Service (PL04) Contractor Book Set

This set of books includes all required references for the Residential Service (PL04) exam. Orders placed before 2 PM are shipped the same day via UPS and a tracking number is emailed before 3 PM.

  • WASHINGTON RESIDENTIAL SERVICE (PL04) - BOOK SET WITHOUT TABS INCLUDES ALL BOOKS FOR TRADE AND BUSINESS EXAMS

    Sales price: $271.31
  • WASHINGTON RESIDENTIAL SERVICE (PL04) - BOOK SET WITH TABS INCLUDES ALL BOOKS FOR TRADE AND BUSINESS EXAMS

    Sales price: $291.31

Washington Residential Service (PL04) Contractor Exam Books

Books Not Allowed in Testing