5 Green Flags to Look For When Hiring a Plumbing Sub
A general contractor's quick guide to spotting a plumbing partner who'll actually make your job easier.
Every general contractor has a story about a contractor who looked fine on the bid and turned into a headache later on. Plumbing is one of those trades where a bad pick doesn’t show up right away, and by the time it does, it could affect your schedule and cause extra expenses.
The good news is the signs of a solid plumbing partner are usually visible before you ever commit to anything. Read on for the green flags worth looking for.
1 They’re licensed, and they’ll prove it
In Washington, this isn’t optional. Since 2021, it’s been unlawful for a company to bid on or perform plumbing work without a plumbing contractor license backed by a designated journey-level certified plumber. You can read more on that here. A good subcontractor hands you the license number without hesitation. You can confirm it quickly by using L&I’s Verify a Contractor tool, which shows you the status, expiration, bond, and any relevant history. If a plumber gets hesitant when you ask, that tells you all you need to know.
2 Bonded and insured, with the paperwork ready to go
Washington requires every licensed plumbing contractor to carry a $6,000 bond and at least $250,000 in general liability insurance, in addition to having a certified plumber on staff. More on Washington L&I can be found here.
3 They talk permits and code before you have to ask
Plumbing in Washington must meet the 2021 Uniform Plumbing Code, adopted statewide under WAV 51-56 by the WA State Building Code Council. A plumber who knows their trade will tell you up front what needs a permit, offer to pull it, and think about inspections before they are a problem. When a sub brings up code and permitting on their own, that shows they have been through the process and don’t want a failed inspection any more than you do.
4 Experience that matches the actual job
New construction, a big remodel, and a commercial tenant improvement are three different animals. A sub who is great at production homes may be out of their depth on a high-end custom build, and vice versa. The green flag here is specific, relevant experience. Make sure to ask for examples of projects like yours, and listen to whether they understand the ins and outs of that work.
5 Estimates in writing
A real estimate spells out scope and is not just a number scribbled on a spare piece of paper. Itemized bids protect both of you as they make it obvious what’s included, they make change orders cleaner, and they signal a business that takes its own operations seriously.
6 References and real project photos
Good plumbers can point to their work, including the general contractors they’ve partnered with, photos of finished jobs, and reviews from people in your area. A sub who can hand you a reference or two, or show a job that looks like yours, is a safer bet.
7 They communicate like a partner, not a vendor
Plumbing touches nearly every other trade on a site, so coordination is half the job. The green flag can be straight answers on schedule, an early heads-up when something is going to conflict, and a crew that keeps everything in order so it’s never the reason another process is waiting too long.
8 They stand behind the work
Things occasionally go sideways on any job, but what separates a good subcontractor is what happens next. A clear warranty and a plumber who actually comes back to make it right are important. Make sure to ask how they handle callbacks, as this will tell you a lot about how they’ll handle your roles working together.
A few red flags
Be cautious when anyone won’t give you a license number, wants to work cash-only or without a written contract, drags their feet on a certificate of insurance, gives vague timelines, or dramatically comes in below every other bid. If a number looks too good to be true, it usually is, and you may have to pay the difference later.
The best plumbing subcontractors make your life easier and help your project run more smoothly. They’re licensed and can prove it, insured and organized, they know the code, and stand behind what they install. If you’re building in the Snoqualmie Valley or King County and want a plumbing partner who checks those boxes, we’d love to talk about your next project.
