Wood vs Composite Deck Cost Over Time (20×12 Deck Comparison)

When planning a new deck, one of the biggest questions homeowners ask is:

Should I build a wood deck or a composite deck?

Wood decks cost less upfront, while composite decks require much less maintenance. The real difference becomes clear when you look at the total cost over time.

In this guide, we’ll compare the build cost and maintenance cost of a 20×12 deck (240 sq ft) over a 10–15 year period.

Average Cost to Build a 20×12 Deck

A 20×12 deck is a very common size for homes and provides about 240 square feet of outdoor space.

The final price depends on several factors including:

• Deck material

• Railings

• Stairs

• Site conditions

• Labor and permits

But most decks fall within a predictable price range.

Pressure-Treated Wood Deck Cost

Pressure-treated wood is the most affordable decking material and remains very popular because of its natural look and lower upfront cost.

Average Build Cost

Typical installed price:

$30 – $45 per square foot

For a 240 sq ft deck, that usually comes out to:

• Low end: $7,200

• High end: $10,800

Most homeowners spend around:

$8,000 – $11,000

Wood Deck Maintenance Costs

Wood decks require regular maintenance to protect them from weather and moisture.

Typical maintenance includes:

• cleaning the deck

• staining or sealing every 2–3 years

• replacing cracked or warped boards

• tightening fasteners

For a 20×12 deck, staining typically costs:

$500 – $900 per treatment

Over 10 years, most decks will need 3–4 stainings, which adds up to:

$1,500 – $3,500 in maintenance.

Composite Deck Cost

Composite decking is made from a blend of recycled wood fibers and plastic. It’s designed to resist moisture, fading, and rot.

Because of this durability, composite decks cost more initially but require very little maintenance.

Average Build Cost

Typical installed price:

$45 – $85 per square foot

For a 240 sq ft deck, that equals:

• Low end: $10,800

• High end: $20,400

Most homeowners spend around:

$12,000 – $18,000

Composite Deck Maintenance

One of the biggest advantages of composite decking is its low maintenance.

Unlike wood decks, composite boards do not require staining or sealing.

Maintenance usually involves:

• occasional washing

• basic cleaning

Over 10 years, most homeowners spend only:

$200 – $500 total.

10-Year Cost Comparison (20×12 Deck)

By around the 8–10 year mark, the cost difference between wood and composite begins to shrink because of maintenance expenses.

Many Wood Decks Need Replacement After 10–15 Years

Another important factor homeowners often overlook is long-term durability.

Wood decks require consistent upkeep to prevent damage from:

• moisture

• sun exposure

• mold and mildew

• rot and insects

Unfortunately, many homeowners fall behind on this maintenance.

Because of this, a large number of wood decks begin showing significant wear around the 10–15 year mark.

Common issues include:

• splintering deck boards

• warped wood

• loose railings

• rotting boards or framing

At that point, homeowners may need major repairs or a full deck replacement.

Why Composite Decks Last Longer

Composite decking is designed to resist many of the problems that damage traditional wood decks.

Composite boards are resistant to:

• moisture

• rot

• insects

• warping

• splintering

With basic cleaning and minimal upkeep, many composite decks can last 20–30 years or longer.

Which Deck Option Is Best?

Both materials have their advantages depending on your priorities.

Wood Decks Are Best For

• Lower upfront cost

• Natural wood appearance

• Homeowners comfortable with maintenance

Composite Decks Are Best For

• Low maintenance

• Long lifespan

• Modern appearance options

• Better resistance to weather and rot

Estimate Your Deck Cost

Every deck project is different depending on the size, materials, and features.

If you want a better idea of what your project might cost, try our deck cost calculator to estimate pricing based on your deck size and material choice.

Planning a New Deck?

If you’re considering a new deck installation or deck replacement, working with an experienced deck builder can help ensure your project is built safely and designed to last.

Whether you choose pressure-treated wood or composite decking, the right design and professional installation will make a big difference in the long-term performance of your deck.