How Much Would a 20x20 Deck Cost to Build?

When homeowners start planning their dream outdoor living space, one of the first questions that comes up is: how much does a 20x20 deck cost to build? A 20x20 deck gives you 400 square feet of usable outdoor space — large enough for outdoor furniture, grilling, entertaining, or simply enjoying quiet evenings outside.
On average, a 20x20 deck will cost between $16,000 and $24,000 or more, depending on the materials chosen, labor costs, location, and the complexity of the design. While this may seem like a wide range, it reflects the number of decisions that go into building a deck, from the type of wood or composite material you use to the railing style, finishes, and additional features you want to include.
In this guide, we’ll break down the costs, compare material options, explore key factors that affect pricing, and share tips on how to get the most accurate estimate for your project.

Why Deck Size Matters

The size of your deck directly impacts the cost. A 20x20 deck equals 400 square feet, which is considered mid-to-large in residential terms. With more square footage comes a greater need for materials, labor, and structural support.
For example:

• A 10x10 deck (100 sq ft) might cost between $4,000–$7,000.
• A 20x20 deck (400 sq ft) costs roughly four times more because it requires four times the materials and significantly more labor.

This scaling is why deck projects can quickly increase in cost as you expand the size.

Key Cost Factors for a 20x20 Deck

1. Materials
The single biggest factor affecting deck cost is the material you choose. Different decking materials vary widely in price, longevity, and maintenance needs.

• Pressure-Treated Wood:
  This is the most budget-friendly choice. Pressure-treated pine typically costs $25 to $50 per square foot installed. It’s strong and functional but requires ongoing upkeep — sealing and restaining every year to protect against weather damage.
• Premium Natural Woods (like Redwood, Cedar, or Exotic Hardwoods):
  Premium woods cost more upfront but offer a rich, natural aesthetic. They typically run between $4 to $20 per square foot for materials alone, before labor. These woods are naturally resistant to decay, but still require regular staining and sealing.
• Composite and Vinyl Decking:
  Composite materials (such as Trex) and vinyl decking are highly durable, weather-resistant, and low-maintenance. They typically cost $5 to $20 per square foot for materials, making them pricier than pressure-treated wood. However, they save money over time by reducing maintenance costs and lasting longer.

2. Labor
Labor is often as significant as material cost — sometimes even more. Labor costs can vary based on:

• Your location (urban vs. rural pricing differences).
• The expertise of the contractor you hire.
• Project complexity (custom features, curved designs, built-in benches, or multi-level decks).

On average, labor accounts for 50% or more of the total deck cost. A simple 20x20 deck may take a crew a week to complete, while a custom project with added features could take much longer.

3. Design Complexity
Decks come in all shapes and styles. A basic rectangular deck is the most affordable option, but adding elements such as:

• Decorative railings
• Built-in seating
• Stairs and multiple levels
• Lighting systems
• Pergolas or covered areas

…will significantly increase costs. Each added feature requires additional planning, materials, and skilled labor.

4. Location
Where you live plays a large role in your final cost. Material prices and labor rates vary by region. For example, building a deck in Salt Lake City, Utah, will have different pricing than a coastal or high-demand metro area. Additionally, local building codes and permit requirements can add to overall expenses.

Material Cost Comparison (Excluding Labor)

To give you a clearer picture, here’s how different decking materials stack up in terms of material-only costs (not including installation):

• Pressure-Treated Pine: $25 – $50 per square foot installed.
• Premium Natural Wood (Redwood, Cedar, Exotic): $4 – $20 per square foot (materials).
• Composite Wood: $5 – $20 per square foot (materials).

When you add labor, the total installed cost of a 20x20 deck lands between $16,000 – $24,000+ depending on choices.

Long-Term Value: Wood vs. Composite

When planning your budget, it’s important not only to look at the upfront price but also at long-term value.

• Wood Decks may cost less initially but require regular maintenance, which adds up over the years. Staining, sealing, and replacing boards that warp or rot can increase long-term costs.
• Composite Decks are more expensive upfront, but because they’re resistant to moisture, fading, and insects, they require minimal upkeep. Over a 20-year lifespan, composite decking often ends up being more cost-effective.

Additional Costs to Consider

Beyond the deck itself, there are a number of other costs you may need to budget for:

• Permits: Depending on your city or county, building permits can range from $100 to over $500.
• Foundation/Footings: Larger decks require stronger footings, which add labor and materials.
• Railings: Depending on the material, railings can cost $15–$40 per linear foot.
• Stairs: Each step can add $30–$50 or more.
• Extras: Built-in benches, planters, lighting, and pergolas can add thousands to your project.

How to Get an Accurate Estimate for Your 20x20 Deck

While online estimates can give you a ballpark number, the only way to know what your deck will truly cost is to get a professional consultation. Here are the steps to take:

1. Choose Your Material: Decide whether you want pressure-treated wood, premium hardwood, or composite decking.
2. Research Local Prices: Contact local suppliers or deck contractors in your area to compare costs.
3. Consider Additional Features: Create a list of “must-haves” and “nice-to-haves” so your contractor can provide you with tiered estimates.
4. Get Multiple Quotes: Always get at least 2–3 bids from reputable deck builders to compare labor and design ideas.
5. Ask About Warranties: Many professional deck builders offer warranties on both materials and labor, which can provide peace of mind.

Cost-Saving Tips Without Cutting Corners

Building a deck is a major investment, but there are ways to manage your budget wisely:

• Go Simple with the Design: A rectangular deck is the most affordable shape. Avoid curves and complex layouts if you want to keep costs down.
• Mix Materials: Consider using composite for the decking surface (for durability) and pressure-treated wood for the frame and structure.
• Build in Stages: If budget is tight, you can build the basic deck first, then add features like pergolas or built-in seating later.
• DIY Where Possible: While you should always hire pros for structural work, you may be able to save on labor by handling finishing touches like painting or staining.

Is a 20x20 Deck Worth the Investment?

Absolutely. A well-built deck not only improves your outdoor lifestyle but also adds significant value to your home. According to remodeling cost reports, decks consistently deliver a solid return on investment (ROI) — often recouping 65–75% of their cost when you sell your home.
Beyond financial return, a 20x20 deck provides:

• Ample space for family gatherings and outdoor entertaining.
• A comfortable extension of your living area.
• An attractive feature that sets your home apart in the market.

Final Thoughts

Building a 20x20 deck is a sizable project, but it’s also one of the most rewarding investments you can make in your home. With an average cost ranging from $16,000 to $24,000+, your final price will depend on the materials you choose, the complexity of your design, local labor costs, and the features you add.
Choosing between wood and composite, deciding on extras like lighting or railings, and working with an experienced local deck builder will ensure you get a structure that’s safe, durable, and perfectly suited to your lifestyle.

Ready to Build Your 20x20 Dream Deck?

If you’re in Utah and thinking about building a deck, don’t leave your investment to chance. At Salt Lake City Decks, we specialize in creating beautiful, durable decks tailored to your needs and budget. Whether you’re looking for a budget-friendly wood option or a long-lasting composite deck, our team will guide you every step of the way — from design to construction.
Call us today at +1 (385) 364-1349 to schedule your consultation and get a personalized quote. Let’s turn your backyard into the outdoor living space you’ve always dreamed of.