A 400 sq ft Trex deck typically costs $12,000-$24,000 installed, with an average near $17,000 for standard composite boards and a pressure-treated frame. Trex product line, deck height, railing, demolition, and local labor rates can shift the quote substantially.
| Item | Low | Average | High | Notes |
|---|---|---|---|---|
| Installed 400 sq ft deck | $12,000 | $17,000 | $24,000 | Basic to upgraded build |
| Installed price per sq ft | $30 | $42.50 | $60 | Frame, labor, and standard finish |
| Trex decking boards only | $5 | $8 | $15 | Per sq ft; varies by product line |
| Railing | $40 | $70 | $120 | Per linear ft, installed |
What a 400 Sq Ft Trex Deck Usually Costs
For a straightforward, ground-level 400 sq ft deck, expect roughly $12,000-$18,000 using entry-level or midrange Trex boards, a pressure-treated frame, and simple stairs or no stairs. A raised deck, premium Trex line, composite fascia, and matching railing can bring the total to $20,000-$24,000 or more.
Installed estimates commonly fall around $30-$60 per sq ft. That range assumes a new deck with ordinary access and no major grading, structural repair, or complex design. A practical planning figure is about $17,000, or $42.50 per sq ft, for a standard midrange installation. Assumptions: typical U.S. labor rates, standard rectangular layout, pressure-treated framing, and normal site access.
How Trex Boards, Framing, and Labor Shape the Quote
Decking boards are only one part of the project. The frame, fasteners, stairs, railing, and installation labor can equal or exceed the board expense, especially when the deck is elevated or has detailed borders. The table shows typical installed allowances for a 400 sq ft project; actual quotes may group several items together.
| Quote component | Low | Average | High | Typical basis |
|---|---|---|---|---|
| Trex boards and fasteners | $2,000 | $3,600 | $6,000 | $5-$15 per sq ft |
| Frame and footings | $2,400 | $3,600 | $5,200 | Pressure-treated lumber, posts, concrete |
| Labor | $4,000 | $6,000 | $8,500 | Layout, framing, decking, finishing |
| Railing, stairs, fascia | $1,000 | $2,500 | $5,000 | Depends on linear footage and design |
| Removal, delivery, permits | $300 | $1,300 | $3,000 | Varies by site and local rules |
Labor often prices to roughly $10-$22 per sq ft, depending on access, height, and detail. Ask whether the quote includes footings, hardware, disposal, stairs, and railing before comparing totals.
How Deck Height, Trex Line, and Shape Change the Price
Trex product lines have different board prices, finishes, and warranties. Moving from an entry-level board to a premium or capped composite option can add several thousand dollars across 400 sq ft. A picture-frame border, diagonal layout, hidden fasteners, or contrasting colors also increases cutting and installation time.
Height is another major driver. A deck less than 2 feet above grade may need little or no railing, while a deck 4 feet high typically requires stronger structural details, stairs, and guardrails under applicable local code. Each additional 100 sq ft adds roughly $3,000-$6,000 at typical installed rates; complicated shapes can cost more per square foot than a simple rectangle. Confirm the Trex line and finished deck height in writing because both can materially alter the estimate.
How Many Labor Hours Does a 400 Sq Ft Build Need?
A basic build may take a three-person crew about 5-8 working days, or roughly 120-190 crew-hours, including framing and board installation. Stairs, railing, demolition, or difficult access can extend the schedule to 8-12 days. Contractor labor rates vary, but a broad planning range is $50-$100 per worker-hour before overhead and materials.
Permit review, footing inspections, and weather can add calendar time without adding the same amount of billable labor. Compare the crew size, included work, and estimated schedule rather than judging a quote by its total labor hours alone.
Regional Labor Rates Can Move a Trex Deck Estimate
Labor and permitting create noticeable regional differences. A comparable project may run 10%-20% below the national planning range in lower-cost rural markets, while major metro areas in the Northeast, West Coast, or Hawaii can be 15%-30% higher. Local material delivery costs and seasonal contractor demand also affect the final price.
For example, a $17,000 standard estimate could be around $14,000-$15,500 in a lower-cost area or $19,500-$22,000 in a high-cost metro. These are planning comparisons, not fixed regional tariffs. Use quotes from nearby contractors to establish a local baseline, and compare the same board line and project scope.
When Stairs, Railing, and Old-Deck Removal Add Up
Railing is often priced by length, with basic composite or metal systems around $40-$80 per linear ft installed and upgraded systems reaching $120 per linear ft. A 20-foot railing run could therefore add approximately $800-$2,400. Stairs commonly add $800-$2,500, depending on width, landings, and height.
Removing an existing deck can add $3-$8 per sq ft, or about $1,200-$3,200 for 400 sq ft, including hauling in many markets. Difficult access, concrete footings, or disposal restrictions may raise the charge. Permit and inspection fees often total $100-$800, but local rules differ. Check whether demolition, haul-away, permit fees, and stair details are included rather than listed as later extras.
Which Trex Deck Choices Can Keep the Budget Down?
A simple rectangle, standard board direction, and one consistent color reduce cuts and material waste. Keeping the deck near ground level can limit stairs, railing, and structural costs, provided drainage and local code requirements are met. A pressure-treated frame is usually less expensive than a composite or steel substructure.
Before approving a premium board or elaborate border, ask for a separate price for the upgrade and compare it with a midrange Trex option. Get at least three itemized bids based on the same dimensions, railing length, stair count, and removal needs. Scheduling outside peak spring and summer demand may improve availability, though discounts are not guaranteed. The largest savings usually come from controlling height, layout, and add-ons—not cutting required framing or safety work.