A bad deck contractor can cost you $5,000–$15,000 in repairs before your new structure even weathers its first winter. Checking references and viewing past work separates professionals who'll deliver a solid investment from those who cut corners and disappear. Here's exactly how to vet a deck, pergola, or patio contractor before you sign.
Call Past Clients—Don't Just Read Reviews
References provided by the contractor are inherently biased, but phone calls reveal details that written testimonials can't. Ask about the timeline, budget accuracy, site cleanliness during construction, and whether the contractor responded to warranty issues. Specifically, ask if the project stayed within 10% of the quoted price (a typical industry tolerance) and whether completion happened within the agreed window.
Request at least three references from projects completed within the last three years. Deck wood degrades over time, and a 10-year-old project won't tell you if the contractor's current methods hold up—you want recent work.
Visit Sites in Person
Photos on a contractor's website are curated. Ask permission to visit completed projects in your area, ideally within five miles so you can see how local climate has treated the work. Look for:
- Fastener condition: Are bolts, screws, and hardware rusted? Stainless steel or coated fasteners indicate quality.
- Wood grain and finish: Pergolas and deck surfaces should show consistent stain or sealant color without blotchy patches.
- Stairs and railings: Do they feel solid, or is there wobble? Loose railings suggest poor post-to-frame attachment.
- Drainage: Can water pool under the structure, or is the site graded properly with space for airflow beneath?
- Board spacing: Composite and pressure-treated decks should have consistent 1/8-inch gaps between boards to allow expansion.
Spend 10 minutes walking the site. If the homeowner is present, chat with them—they'll give you the unfiltered truth about service quality.
Review Their Insurance and Licensing
A contractor without general liability insurance is one accident away from you being sued as the homeowner. Request a certificate of insurance naming you as an additional insured for the duration of the project. Verify their state contractor license (most states require them for projects over $2,000–$5,000) by checking your state's licensing board website.
Ask whether they carry workers' compensation insurance. If they work alone and claim they don't need it, confirm they're a sole proprietor licensed to self-insure in your state—liability still matters.
Check Industry Credentials
Organizations like the National Association of Home Builders (NAHB) or the Deck Industry Association (DIA) offer member directories and occasionally verify credentials. A contractor certified in composite or pressure-treated deck installation has training in fastening, ventilation, and seasonal movement—things that separate $8,000 decks that last 20 years from $8,000 decks that rot in eight.
Many regions have deck-specific associations. In the Pacific Northwest, the Western Red Cedar Lumber Association provides guides and certified contractor lists. Your local landscape supplier or building department often knows which contractors consistently pass inspections.
Compare Warranty Terms
A solid contractor backs their work with a written warranty—typically two years for labor and five to 10 years for materials (depending on decking type). Request the warranty document in writing; verbal promises won't help if the contractor disappears. Clarify what's covered: does it include fading, minor cracks, or only structural failure?
Pressure-treated decks and composite decking carry different warranties. Composites usually cost $3,000–$8,000 more than pressure-treated, so the material warranty matters when comparing long-term value.
Request a Detailed Written Estimate
Before hiring, get a detailed quote listing specific materials (lumber grade, fastener type, stain brand), labor cost, timeline, and payment schedule. Vague estimates like "$12,000 for a 16×12 deck" are red flags. You want line items: "Pressure-treated 2×8 rim joists: $800," "Composite decking (Trex Select, $6/sq ft): $4,200," and so on.
Mercoly helps you compare and find trusted deck, pergola, and patio contractors in your area—reviewing their verified past work, credentials, and customer feedback all in one place.
Frequently Asked Questions
Q: What should I do if a contractor's references have moved or won't take my call? A: Request at least five references instead of three, as some will inevitably be unresponsive. If multiple references avoid or delay answering questions, that's a warning sign—move to the next contractor.
Q: How long should a composite pergola or patio last? A: Quality composite structures last 25–30 years with minimal maintenance, while pressure-treated wood typically lasts 15–20 years depending on local climate and upkeep.
Q: Is the cheapest quote always a bad sign? A: Not always, but it often is—bids that undercut others by 20%+ typically mean cut corners on fasteners, lumber grade, or labor hours. Compare quotes within 10% of each other to identify the true value leader.
Get estimates from at least three contractors and verify references before deciding.