600 sqft · 20×30 ft

20×30 Deck Cost

A 20×30 deck (600 sqft) is among the largest typical residential decks — often multi-tier with a kitchen wing. The calculator below is pre-loaded with these dimensions — change the state, finish tier, or scope to recalculate live.

Get 2–3 free quotes

600 sqft100 ft perimeter5 finish tiersAll 50 states2026-Q1 pricing

20×30·Footprint

600·Sq ft

100·Perimeter ft

<2s·Live calc

How much a 20×30 deck costs by material

Material$/sqft installed20×30 total (600 sqft)

Pressure-treated wood

Cheapest to build; re-stain every ~2 years.

$25–$40$15,000–$24,000

Cedar / premium PT

Warmer look than PT; ages to silver, re-stain every ~3 years.

$35–$55$21,000–$33,000

Composite — mid-range

Trex Enhance, Fiberon Good Life. Wash-only; best 25-year value for most.

$50–$80$30,000–$48,000

Composite / PVC — premium

Trex Transcend, TimberTech AZEK. Longest warranty, coolest underfoot.

$75–$110$45,000–$66,000

Tropical hardwood (Ipe)

Ipe, Cumaru. Stunning and dense; pre-drill every fastener.

$90–$140$54,000–$84,000

A 20×30 deck is 600 sq ft. In pressure-treated wood that runs about $15,000–$24,000 installed — the cheapest way to get a deck this size, though you'll re-stain it every couple of years. Step up to mid-range composite (Trex Enhance, Fiberon Good Life) and the same 600 sq ft is $30,000–$48,000: roughly double the upfront, near-zero maintenance, and usually the lower 25-year cost.

Premium composite or PVC (Trex Transcend, TimberTech AZEK) lands around $45,000–$66,000, and tropical hardwood like Ipe tops out near $54,000–$84,000. These are installed (material + labor) for a simple rectangle — an L-shape adds ~10%, a wraparound ~22%, and a tall or hard-to-access deck up to 40%. Regionally, the South runs about 8% under these national figures and the West Coast about 28% over.

The calculator below itemizes a complete project — framing, footings, railing, stairs, permit, and contingency — so its total runs higher than the surface-and-labor bands above for the same size.

Inputs

Dimensions

Plan-view length × width.

Lengthft

Widthft

Area · 600 sq ft·Perimeter · 100 ft

Material tierinstalled $/sqft band

State2-letter · labor multiplier

Footprint shape1.00× complexity

AttachmentShares house structure

Deck heightinches

IRC R312 requires a 36″ guardrail above 30″.

Stairssteps

Site accessDriveway / wide-open backyard

Scope toggles

Project budget · Northeast

$44,008 – $77,354

$73–$129/ sq ft

600 sq ft · Mid composite · 1.22× labor · 1.10× complexity

Materials

Low $14,850

Labor

Low $22,143

Add-ons

Low $6,337

Soft costs

Permit · demo · design

Project advisories · IRC 2021

Guardrail included (deck 36″ off grade)

IRC R312

IRC R312 mandates a 36″ guardrail on open edges when deck height exceeds 30″. 70 lf priced at Mid composite tier.

Building permit included in budget

IRC R105

Northeast typical permit fee is in the budget. Most jurisdictions require a permit for decks > 200 sqft, > 30″ above grade, or attached to the house.

Hidden-fastener install premium baked in

Manufacturer specs

Mid composite uses hidden-fastener clip systems (Cortex / CamoClip / Trex Universal) — labor takes 25–30% longer than face-screwing PT. Already inside the tier's installed $/sqft band.

Cost breakdown

Materials31%$23,760
Labor46%$35,429
Add-ons14%$10,455
Soft costs1%$678
Contingency9%$7,032
Share of the high estimate. Switch tiers below to repaint the split.

Item

Qty

Total

Labor (Northeast, 1.22× national)

$22,143 – $35,429 (low – high estimate)

1.0 scope

$35,429

Labor (Northeast, 1.22× national)

$22,143 – $35,429 (low – high estimate)

1.0 scope

—

$35,429

Materials (decking + framing + hardware)

$14,850 – $23,760 (low – high estimate)

Home Depot Lowe’s

1.0 scope

$23,760

Materials (decking + framing + hardware)

$14,850 – $23,760 (low – high estimate)

Home Depot Lowe’s

1.0 scope

—

$23,760

Railing (70 lf, ledger 3-side)

$4,697 – $8,113 (low – high estimate)

1.0 scope

$8,113

Railing (70 lf, ledger 3-side)

$4,697 – $8,113 (low – high estimate)

1.0 scope

—

$8,113

Contingency (10% reserve)

up to $7,032

1.0 scope

$7,032

Contingency (10% reserve)

up to $7,032

1.0 scope

—

$7,032

Stairs (4 steps @ 9.0″ rise)

$1,640 – $2,342 (low – high estimate)

1.0 scope

$2,342

Stairs (4 steps @ 9.0″ rise)

$1,640 – $2,342 (low – high estimate)

1.0 scope

—

$2,342

Building permit (Northeast)

$678 flat

1.0 scope

$678

Building permit (Northeast)

$678 flat

1.0 scope

—

$678

Materials subtotal

$77,354

National-median pricing (2026-Q1). Local prices vary ±15%. Materials line uses Mid composite tier; switch tiers to repaint the budget. Includes 10% contingency reserve on the high estimate.

Live preview

Visualize your deck

Photoreal 3D · plan view · framing breakdown. Color matches your tier selection.

PBR materialsHDR lightingMid composite

Loading 3D scene…

DeckMath·30′ × 20′·600 sq ft

Trex Enhance·composite

Drag · pinch / scroll

Joists

23 × 20′

Beams

1 × 2-ply 2×10

Posts

5 × 6×6

Boards

44 rows

Project all-in

Materials (low – high)

Mid composite tier · Trex Enhance · Fiberon Good Life · TimberTech Prime+. ~$0.05/sqft/yr.

$14,850 – $23,760

Labor (installed)

Northeast · 1.22× national index

$22,143 – $35,429

Add-ons

Railing · stairs · lighting (only included items)

$6,337 – $10,455

Soft costs

Permit · demo · design (only included items)

$678 – $678

Contingency reserve (10%)

Industry-standard cushion for unforeseen scope

$7,032

Project total (low – high)

Plan around the high. Get 3 contractor bids — DeckMath should land within ±15%.

$44,008 – $77,354

Same dimensions, different tier

tap to switch

DIY savings

$35,893

vs mid-range contractor

Materials only: $23,760
Estimated hours: 900 hr
Skill required: advanced

Finance estimate

$1,568/month

60-month personal loan @ 7.99% APR

Principal: $77,354
Total interest: $16,731
Estimate only — shop 3+ lenders.

Composite/PVC installs use hidden-fastener clip systems — labor is 25–30% slower than face-screwing pressure-treated wood. That premium is already baked into the tier's installed $/sqft band.

Need exact board counts?

The Deck Material Calculator gives you a permit-ready bill of materials — every joist, hanger, fastener, and footing — validated against IRC 2021 span tables.

Open

Estimates use 2026-Q1 national-median pricing (Home Advisor, Angi, RSMeans). Expect ±15% variance vs your local market. Always get 3 contractor bids before signing. This calculator is not a substitute for a licensed inspector or structural engineer.

Estimated material takeoff — 20×30

The framing and decking a 20×30 (600 sqft) deck needs — board, joist, beam, post, footing, and railing quantities computed from the dimensions at 16″ joist spacing with a 10% waste factor.

Component

Quantity

How it's estimated

Decking boards (16′ × 5/4×6)

91 boards · 1440 lf

600 sqft ÷ 5.5″ face × 10% waste

Joists (2×8 @ 16″ o.c.)

24 joists · 480 lf

⌈30′ × 12 ÷ 16″⌉ + 1, each 20′ long

Beam lumber (3× 2-ply built-up)

180 lf

3 beam lines × 30′ × 2 plies

Posts (6×6 PT) + footings

15 posts · 15 footings

3 lines × (⌈30′ ÷ 8⌉ + 1) posts at ≤8′ o.c.

Footing concrete (60-lb bags)

79 bags · 35.3 cu ft

15 piers @ 12″⌀ × 36″ deep — adjust depth to local frost line

Joist hangers (Simpson LUS)

24 hangers

one per joist at the ledger / beam connection

Railing run

70 lf

100 lf perimeter − 30′ ledger side

Decking face screws

≈ 4,321 screws

≈2 screws per board at each joist crossing

Decking

91 boards

1440 lf incl. waste

Joists

16″ o.c. · 480 lf

Posts / footings

79 × 60-lb concrete

Railing

70 lf

100 lf perimeter

Estimated quantities for planning and budgeting — round up when ordering. Beam sizing, post spacing, and footing depth must follow your local code and a stamped plan (frost line, soil, and snow load vary by region per IRC 2021 / AWC DCA-6).

FAQ — 20×30 deck

How much does a 20×30 deck cost?

A 20×30 deck (600 sqft) costs $15,000-$24,000 for budget pressure-treated construction, $30,000-$48,000 for mid-range composite, and $54,000-$84,000 for premium composite or tropical hardwood. National-average pricing — multiply by 0.92× for the South or 1.28× for West Coast labor.

How many boards do I need for a 20×30 deck?

Running 5/4×6 or 1×6 deck boards (5.5″ face, 1/8″ install gap) parallel to the long dimension: rows = ceil(20 × 12 ÷ 5.625) = 43 rows. Total LF = 43 × 30 × 1.07 (7% waste, parallel pattern) ≈ 1381 LF. Round up to 20-ft stock for typical 70 boards.

How long does it take to build a 20×30 deck?

For a contractor crew (2-3 people), a 20×30 deck takes 6-10 days depending on complexity, including framing + decking + railing + inspection wait. DIY single-person build: 90-113 weekend days for composite, less for pressure-treated.

Do I need a permit for a 20×30 deck?

In most US jurisdictions, yes. IRC 2021 R105 requires a permit for any deck above 30″ off grade, attached to the house, or larger than 200 sqft. A 20×30 deck (600 sqft) exceeds the 200-sqft threshold and definitely requires a permit.