Filing a mechanics lien claim could certainly help to get paid for materials and labor that went into a construction project. And, if you've gone unpaid for work that permanently improved the project property, then this might be a helpful resource: Washington Mechanics Lien Guide and FAQs.
Granted, before filing a mechanics lien, there are less-aggressive tools for recovery like sending invoice reminders, payment demand letters, and even a Notice of Intent to Lien. Plus, if those options don't work, then the claimant could presumably still pursue a lien claim.
Finally, legal options - such as a breach of contract claim - would likely be on the table, and taking those claims to Washington small claims court could help to streamline things and keep the costs down.