Most homeowners get one vinyl deck install in their life. They're flying blind. Here are the questions I'd ask if I were on the other side of the table.
About the installer
1. How many vinyl decks have you installed, and in what years? You want someone who's done hundreds, not dozens. Ask for recent references you can call.
2. Are you certified by the manufacturer you're proposing? Most quality brands certify installers after training. If they're not certified by the product they're installing, ask why.
3. Do you carry liability and workers' comp insurance? Ask for proof. If someone gets hurt on your property and they don't have insurance, you might.
4. Do you offer a workmanship warranty in writing? If yes, for how long, covering what? Get it in the contract.
About the product
5. What's the membrane thickness and backing type? Should be 60mil minimum, 68mil for high-traffic balconies. Fleece or woven-scrim backing. If they don't know or can't answer clearly, that's a flag.
6. Are all seams heat-welded? Must be yes. If they say "mostly" or hedge, walk away. This is non-negotiable.
7. What adhesive are you using? Should be the manufacturer's approved adhesive for the membrane. Ask for the product name. Look it up.
About the install
8. How will you handle the substrate? What do they see? Will they patch, sand, replace, or work over the existing surface? What adds cost if problems are found mid-install?
9. Where's the slope going? Vinyl deck membranes need ¼ inch per foot minimum drainage slope. If your existing deck isn't sloped, they need to build it in. Ask how.
10. How are you terminating at the wall? Termination at the wall interface is one of the most common failure points. You want a proper termination bar with sealant and flashing — not just glue and prayer.
About the timeline and cost
11. What's the detailed cost breakdown? Ask for material cost, labour cost, substrate prep cost, and any contingencies separately. If they refuse to break it down, they're probably marking up material significantly.
12. What changes the price mid-project? Rot under the deck, hidden drainage issues, joist problems — these happen. Ask what their rates are for unexpected work. Get it in writing before they start.
Red flags
- Can't produce insurance or certification paperwork
- Won't put the warranty in writing
- Pressure to sign same day
- Significantly lower than other quotes (usually substrate work being skipped)
- "We don't need to do X" where X is flashing, termination, or slope
- Refuses to share the material product name and data sheet
The one that catches most people
If an installer gives you a price without seeing the deck in person, that price isn't real. Every vinyl deck project has substrate realities you can only see on site. Insist on a site visit before any quote is final.
Read my cost guide for what a reasonable quote range looks like.
