How much does a pressure-treated deck cost per square foot in 2026?

$25-45/sqft installed, all-in. The variance is mostly driven by species (SYP baseline; coastal Western +18%), brand (YellaWood/Wolmanized +10-12% vs generic), grade (Premium-Select +45% vs No.2), chemistry (MCA/CA-C +$0.04-0.05/bf vs ACQ), and regional labor (Northeast 1.22×, West 1.28×, South 0.92×, Midwest 1.00× baseline). A 16×12 (192 sqft) SYP No.2 UC3B-board / UC4A-joist deck in PA runs ~$5,200-7,800 installed.

What's the difference between UC3B, UC4A, and UC4B pressure-treated lumber?

UC3B (Use Category 3B) is above-ground exterior — deck boards, railings, fascia. Lowest treatment retention (~0.15 pcf for ACQ). UC4A is ground-contact — joists, ledger, beams, ANY framing within 6″ of grade. Retention 0.40 pcf. UC4B is heavy-duty in-ground — fence posts, deck posts in soil, severe-exposure scenarios. Retention 0.60 pcf. IRC R317.1 + AWPA U1 mandate UC4A or higher for ground-contact applications.

Is YellaWood worth the premium over generic pressure-treated lumber?

Often yes — ~10-12% upcharge buys a 25-year limited warranty (rot/fungus/termites), reliably stamped end-tags (so you can verify UC level without guessing), and MCA chemistry that's 50% less corrosive than ACQ-treated generic stock (standard G185 fasteners safe vs needing stainless). For a 192 sqft deck the warranty premium adds ~$250-400. Worth it when you're staying in the house long-term; less critical for flip/rental scenarios.

Should I choose ACQ or MCA pressure-treated lumber?

MCA — for any new build. ACQ (Alkaline Copper Quat) was the original CCA replacement (post-2003 ban) but its high copper concentration is corrosive to standard galvanized steel — 9/10 on the corrosivity scale. ACQ REQUIRES stainless (305-grade) or G185 hot-dipped galvanized fasteners; standard zinc-plated screws will rust through in 3-5 years. MCA (Micronized Copper Azole) cuts corrosivity in half (4/10) — modern HDG-185 fasteners are fine, and it's the chemistry behind YellaWood, Weather Shield, and most current Home Depot stock.

What's the 25-year total cost of ownership for a pressure-treated deck?

For a 192 sqft SYP deck: ~$6,500 initial install + ~$2,200 maintenance (12× biennial sealer @ $164 each + 5× full stain @ $278 each) + ~$1,500 board replacement reserve year-20 = ~$10,200 over 25 years (~$2.13/sqft/year). Composite equivalent: ~$11,500 install + ~$480 maintenance = ~$12,000 (~$2.50/sqft/year). PT comes out ~$1,800 cheaper IF you actually do the biennial maintenance — skip it and PT life drops to ~12 years and you're replacing the deck instead.

Can I use Hem-Fir or SPF for joists instead of SYP?

Yes but with a span penalty. AWC DCA-6 joist spans: SYP 2×8 @ 16″ o.c. 40 psf LL = 12′-10″. Same SPF 2×8 = 11′-1″ (13% less). Hem-Fir 2×8 = 11′-7″ (9% less). Coastal Douglas-Fir actually beats SYP at 13′-4″. SPF/Hem-Fir also treat less deeply — for UC4A ground-contact applications, every board MUST show a visible AWPA UC4A end-tag (heartwood may not have absorbed full retention). Cross-check spans with the Joist Span Calculator.

Is pressure-treated cheaper than composite long-term?

Yes — typically 15-25% cheaper over 25 years, IF maintenance is performed. The composite premium ($60/sqft installed vs $35 for PT) is offset by zero maintenance vs PT's $0.45/sqft/yr stain-and-seal. The crossover point is year 28-32 for premium composite (Trex Transcend, TimberTech AZEK Vintage). For shorter ownership ( 35 years, composite wins. The PT TCO model in this calculator assumes you DO the maintenance — skip it and the math flips.

What's the difference between 5/4×6 and 2×6 PT deck boards?

5/4×6 actual = 1.0625″ × 5.5″ — lighter, cheaper (~$1.85/bf SYP UC3B), but needs joists at 16″ o.c. max because it deflects noticeably over 16″ unsupported. 2×6 actual = 1.5″ × 5.5″ — stiffer, allows 24″ o.c. joist spacing (=fewer joists = cheaper framing), but boards cost ~13% more per LF. For most decks, 2×6 boards + 24″ o.c. joists is cheaper overall because you save on joist count. 5/4×6 wins when you want the lightest, lowest-profile board appearance.

pressure-treated · UC3B/UC4A/UC4B · 2026 retail

PT Deck Cost Calculator

Q: What fasteners do I need for ACQ vs MCA treated lumber?

ACQ — stainless steel only (305-grade or 316-grade marine) for screws, joist hangers, and structural connectors. Or G185 hot-dipped galvanized (NOT standard G90 — won't last). MCA + CA-C — HDG G185 hot-dipped is safe; stainless still better in coastal/high-corrosion areas. ASTM A153 is the controlling spec. NEVER use electro-zinc-plated screws on any modern PT — they'll rust through in 3-5 years regardless of chemistry. Joist hangers must match: Simpson HDG ZMAX or stainless 316.

Q: How often should I seal a pressure-treated deck?

Biennial light sealer wash (years 2/4/6/8...) + full stain refresh every 5 years (years 5/10/15/20). The biennial seal (Thompson's WaterSeal, Olympic Maximum) is a 1-day DIY at ~$0.85/sqft (~$165 for a 192 sqft deck). The full stain refresh (Behr Premium, Ready Seal, Cabot Australian Timber Oil) is a 2-day clean-then-stain at ~$1.45/sqft (~$280). Skipping leads to UV silvering, surface checking, and eventual face-grain splintering — un-maintained PT life is 10-12 years vs 18-22 years with full maintenance.

Pressure-treated lumber-specific cost engine — pick species (SYP, SPF, Hem-Fir, Coastal Western), board profile (5/4×6 vs 2×6), grade (No.2, No.1, Premium-Select), AWPA treatment level (UC3B above-ground, UC4A ground-contact, UC4B heavy-duty), chemistry (ACQ, MCA, CA-C, Copper Naphthenate), and brand (YellaWood, Wolmanized, Weather Shield, generic). Returns the real installed cost plus a 25-year total cost of ownership including biennial sealing schedule, year-20 board replacement reserve, and direct comparison to composite TCO. IRC R317 + R507 cross-validated. Pairs with the Deck Cost Calculator (5-tier overview) and Composite Deck Cost Calculator (brand-aware composite).

4 species · 4 brands3 treatment levels4 chemistries25-yr TCOvs compositeIRC R317 + R507Free forever

$25-45·Installed/sqft

4×4×4·Species/brand/UC

ASTM A153·Fastener spec

−$1,800·vs composite 25yr

Inputs

Deck dimensions

Lengthlonger side

Widthshorter side

Deck heightfrom grade

Stair countstairs from grade

Effective area192 sqft

Joist count @ 16″ o.c.13

Posts (6×6 UC4B)4

Total board feet594.1 bf

Species

Board profilethickness × width

Lumber grade

Deck-board treatmentAWPA UC level

Joist treatmentground-contact framing

Treatment chemistry

Brand / treater

Project yearsTCO horizon

State2-letter

Results

Southern Yellow Pine (SYP) · YellaWood (Great Southern Wood) · MCA (Micronized Copper Azole) · PA (Northeast, 1.22× labor)

Initial install

Low $7,168

$/sqft installed

$37–47/sqft

25-yr TCO

Maint $3,024

vs composite

Composite cheaper

Guardrail included — required at 36″ height (>30″)

IRC R312.1

Walking surface 36″ above grade. IRC R312.1.1 requires a 36″ minimum guardrail (R312.1.2). Balusters spaced so a 4″ sphere cannot pass (R312.1.3.1).

Joist treatment UC4A (above-ground OK)

IRC R317.1 · AWPA U1

Deck height 36″ keeps joists well above grade. UC4A specified here for safety margin; UC3B technically allowable above 6″ from grade.

HDG G185 hot-dipped fasteners OK — MCA (Micronized Copper Azole) corrosivity 4/10

ASTM A153 · AWPA M4

MCA (Micronized Copper Azole) is hot-dipped-galv compatible. Use G185 (ASTM A153) for all screws + structural connectors (Simpson HDG ZMAX or equivalent). Stainless still better in coastal/high-corrosion areas.

594.1 bf total lumber order · Southern Yellow Pine (SYP)

AWC DCA-6 prescriptive deck framing

39 deck boards (460.8 lf) · 13 joists × 12′ · 4 posts (6×6 UC4B) · 1 ledger × 16′. 10% waste factor applied to all framing lumber.

Item

Qty

Total

PT railing system

40 lf · 36″ guard height (R312.1.2) · 4×4 posts @ 6′ o.c. · 2×2 balusters @ 4″ sphere rule

1.0 system

$1,240

PT railing system

40 lf · 36″ guard height (R312.1.2) · 4×4 posts @ 6′ o.c. · 2×2 balusters @ 4″ sphere rule

1.0 system

—

$1,240

PT stairs (4 steps)

Cut stringers · PT treads · handrail · IRC R311.7.5 compliant

4.0 step

$840

PT stairs (4 steps)

Cut stringers · PT treads · handrail · IRC R311.7.5 compliant

4.0 step

—

$840

Southern Yellow Pine (SYP) 2×8 joists @ 16″ o.c.

13 joists × 12′ = 156 lf · UC4A ground-contact treatment

13 ea

$577

Southern Yellow Pine (SYP) 2×8 joists @ 16″ o.c.

13 joists × 12′ = 156 lf · UC4A ground-contact treatment

13 ea

—

$577

Southern Yellow Pine (SYP) 5/4x6 deck boards

460.8 lf · 240 bf · NO2 · UC3B treatment · YellaWood (Great Southern Wood)

39 × 12′

$509

Southern Yellow Pine (SYP) 5/4x6 deck boards

460.8 lf · 240 bf · NO2 · UC3B treatment · YellaWood (Great Southern Wood)

39 × 12′

—

$509

Initial sealer/stain application

Year-0 application · 192 sqft × ~$1.50/sqft · required for most warranties

1.0 application

$288

Initial sealer/stain application

Year-0 application · 192 sqft × ~$1.50/sqft · required for most warranties

1.0 application

—

$288

Southern Yellow Pine (SYP) 6×6 posts UC4B

4 posts × 8′ stock · in-ground heavy-duty treatment (≥0.60 pcf retention)

4.0 ea

$257

Southern Yellow Pine (SYP) 6×6 posts UC4B

4 posts × 8′ stock · in-ground heavy-duty treatment (≥0.60 pcf retention)

4.0 ea

—

$257

Hot-dipped G185 galv fasteners + connectors

MCA (Micronized Copper Azole) compatible with HDG-185 (corrosivity 4/10) · screws, joist hangers, post bases

1.0 kit

$197

Hot-dipped G185 galv fasteners + connectors

MCA (Micronized Copper Azole) compatible with HDG-185 (corrosivity 4/10) · screws, joist hangers, post bases

1.0 kit

—

$197

Southern Yellow Pine (SYP) 2×10 ledger

16′ run · UC4A ground-contact (bolt to house rim joist per IRC R507.9)

1.0 ea

$74

Southern Yellow Pine (SYP) 2×10 ledger

16′ run · UC4A ground-contact (bolt to house rim joist per IRC R507.9)

1.0 ea

—

$74

Materials subtotal

$3,982

25-year maintenance schedule

Year	Action	Cost
Y2	Sealer wash + re-coat	$163
Y4	Sealer wash + re-coat	$163
Y5	Full stain refresh (clean + restain)	$278
Y6	Sealer wash + re-coat	$163
Y8	Sealer wash + re-coat	$163
Y10	Full stain refresh (clean + restain)	$278
Y12	Sealer wash + re-coat	$163
Y14	Sealer wash + re-coat	$163
Y15	Full stain refresh (clean + restain)	$278
Y16	Sealer wash + re-coat	$163
Y18	Sealer wash + re-coat	$163
Y20	Full stain refresh (clean + restain)	$278
Y22	Sealer wash + re-coat	$163
Y24	Sealer wash + re-coat	$163
Y25	Full stain refresh (clean + restain)	$278
Y20	Replace ~20% of weathered deck boards	$117
Maintenance total		$3,024

Biennial sealer wash (Thompson's WaterSeal, Olympic Maximum, ~$0.85/sqft) keeps the wood from silvering + checking. Every 5 years a full stain refresh (Behr Premium, Ready Seal, Cabot Australian Timber Oil, ~$1.45/sqft) restores color + UV protection. Skipping maintenance drops PT life from ~22 years to ~12 years.

PT vs composite — 25-year head-to-head

Pressure-treated (this deck)

$12,259

$9,118 install + $3,024 maint + $117 replace

Composite (25-yr benchmark)

$12,000

$60/sqft × 192 sqft + $0.10/sqft/yr maint

Composite is $259 cheaper at this scope. Likely because the project-year horizon (25) is approaching the composite cross-over (~28-32 yrs).

Cost breakdown

Materials (lumber + fasteners + sealer): $3,664 – $3,983
Labor (Northeast 1.22×): $3,504 – $4,460
Subtotal: $7,168 – $8,442
Contingency (8%): $675
Initial install total: $7,168 – $9,118
Maintenance (25 yr): $3,024
Board replacement reserve: $117
25-year TCO total: $12,259

2026-Q1 retail pricing. Materials BoM includes deck boards, joists @ 16″ o.c., 6×6 UC4B posts, ledger, fasteners (hot-dipped-galv), and railing/stairs as scoped. Labor adjusted for Northeast (1.22× national baseline). Excludes permit, design fees, demolition.

How to use

Three steps. Permit-ready output.

Enter footprint + height

Length × width in feet (L = longer side). Pick shape: rectangle or L-shape (L-shape applies a 0.85 area factor + 1.10 complexity premium on perimeter). Deck height in inches drives railing trigger (>30″ → 36″ guardrail required per IRC R312.1) AND joist treatment requirement (≤18″ from grade → UC4A ground-contact mandatory per IRC R317.1).

Pick species + board profile

SYP (Southern Yellow Pine) is the industry standard east of the Rockies — highest strength, best treatment penetration, baseline pricing. SPF saves ~12% but joist spans are 8-15% shorter (use the Joist Span Calculator to verify). Hem-Fir for PNW. Coastal Douglas Fir / Western Red is +18% premium for highest strength — but resists treatment past 1/2″, so use only above-ground. Board profile: 5/4×6 (lighter, cheaper, needs 16″ o.c. joists) vs 2×6 (stiffer, 24″ o.c. acceptable).

Lumber grade + treatment level

Grade controls knots/checking: No.2 (standard, fine for utility decks), No.1 (clearer grade, +18% premium), Premium-Select (cabinet-quality, +45% — only worth it for highly visible work). Treatment level: UC3B (above-ground, deck boards + railings), UC4A (ground-contact, joists + ledger + beams), UC4B (heavy-duty, in-ground posts). IRC R317.1 mandates ground-contact treatment for anything within 6″ of grade.

Chemistry + brand

ACQ (Alkaline Copper Quat) — oldest replacement for banned CCA, highly corrosive to standard galv steel (9/10 corrosivity), REQUIRES stainless or G185 hot-dipped fasteners. MCA (Micronized Copper Azole, modern) — 50% less corrosive (4/10), HDG-185 OK. CA-C (Wolmanized signature) — between ACQ and MCA. Copper Naphthenate — least corrosive, premium/marine-grade. Brand: YellaWood (25-yr) + Wolmanized (30-yr) + Weather Shield (25-yr) all carry warranties; generic = cheapest but no warranty.

Maintenance + TCO scope

Initial sealer/stain application year-0 (~$1.50/sqft) is required for most warranties. The 25-yr TCO models biennial sealer wash ($0.85/sqft every 2 yrs) + every-5-year full stain refresh ($1.45/sqft) + ~20% board replacement at year 20 (~$1,500-3,000 reserve). Adjust TCO years (5-50) to model different ownership periods. Composite comparison benchmark: $60/sqft installed, $0.10/sqft/yr maintenance, 30-yr life.

How we calculate

The math, fully transparent.

The PT Deck Cost Calculator is the pressure-treated-specific cost engine — pick species (SYP / SPF / Hem-Fir / Coastal Western), board profile (5/4×6 vs 2×6), grade (No.2 / No.1 / Premium-Select), treatment level (UC3B above-ground / UC4A ground-contact / UC4B heavy-duty in-ground), chemistry (ACQ / MCA / CA-C / Copper Naphthenate), and brand (YellaWood / Wolmanized / Weather Shield / generic) — and get the real installed cost plus a 25-year total cost of ownership with biennial sealing schedule, year-20 board replacement reserve, and direct comparison to composite TCO. Built on 2026-Q1 retail pricing, AWPA UC treatment standards, and IRC 2021 R317 (decay-resistant lumber) + R507 (deck framing) compliance checks.

IRC references

IRC 2021 R317.1 — Pressure-treated lumber within 6″ of grade or in direct contact
IRC 2021 R507.9 — Ledger connection: 1/2″ lag bolts or through-bolts to band rim
IRC 2021 R312.1.1 — Guardrail required where walking surface >30″ above grade
IRC 2021 R312.1.2 — Guardrail 36″ min height (residential)
AWPA U1-23 — Use Categories UC3B (above-ground), UC4A (ground-contact), UC4B (heavy-duty)
ASTM A153 — Hot-dipped galvanized steel (G185 minimum for MCA/CA-C; stainless required for ACQ)
AWC DCA-6 — Prescriptive deck framing tables (joist spans by species, post tributary areas)

2026-Q1 retail pricing. SYP 5/4×6 No.2 UC3B baseline $1.85/bf; species multipliers SYP 1.00 / SPF 0.88 / Hem-Fir 1.05 / Coastal Western 1.18. Brand multipliers Generic 1.00 / Weather Shield 1.06 / Wolmanized 1.10 / YellaWood 1.12. Grade multipliers No.2 1.00 / No.1 1.18 / Premium-Select 1.45. Treatment level adders UC3B $0 / UC4A $0.12/bf / UC4B $0.28/bf. Chemistry adders ACQ $0 / CA-C $0.04 / MCA $0.05 / Copper Naphthenate $0.08 per bf. Labor $12-22/sqft installed (excluding railing + stairs) × regional multiplier (Northeast 1.22 / West 1.28 / South 0.92 / Midwest 1.00). Maintenance schedule: biennial sealer $0.85/sqft + every-5-yr stain $1.45/sqft + year-20 board-replacement reserve at ~20% of original board cost × 1.15.

Deck-board lumber cost

boardCost = (area / 0.458) × wasteFactor × bfPerLf × pricePerBf

Area divided by board face width (5.5″ = 0.458 ft) gives raw LF, times 10% waste, times BF/LF (0.521 for 5/4×6 or 1.0 for 2×6), times species-and-brand-adjusted $/bf. Treatment + chemical adders applied per-bf.

Joist count + LF

joistCount = ceil(lengthFt × 12 / joistSpacing) + 1

Joist spacing depends on board: 5/4×6 → 16″ o.c., 2×6 → 24″ o.c. acceptable. Joist length = widthFt (perpendicular to long axis). Each joist gets UC4A ground-contact treatment minimum, regardless of deck height.

Post count (6×6 UC4B)

postCount = max(4, ceil(L / 8) × ceil(W / 8))

Posts on 8 ft grid (rule-of-thumb, deck heights up to 4 ft and 40 psf live load). 6×6 PT UC4B heavy-duty treatment for in-ground or on-pier applications. For taller decks (>4 ft) or higher loads, run the Deck Beam Span + Post Spacing calculators.

Treatment + chemistry $/bf adder

pricePerBf = baseBf × speciesMult × brandMult × gradeMult + treatmentAdder + chemicalAdder

Base $/bf compounds with species multiplier (SYP=1.0, SPF=0.88, Hem-Fir=1.05, Coastal=1.18), brand multiplier (Generic=1.0, YellaWood=1.12, Wolmanized=1.10), grade (No.2=1.0, No.1=1.18, Premium=1.45). Then add flat treatment level adder (UC3B=$0, UC4A=$0.12, UC4B=$0.28) and chemical adder ($0-$0.08).

25-yr TCO schedule

tco = projectHigh + sum(maintenance year 2..N) + replacementReserve

Project cost + every-2-yr sealer wash + every-5-yr full stain + year-20 board replacement (20% of original board cost × 1.15 for current pricing). Comparison: composite TCO = installedPerSqft × area + annualMaint × area × years. PT cheaper than composite typically by 30-50% over 25 yrs IF maintenance is performed; un-maintained PT life drops to ~12 yrs and replacement is mandatory at year 15.

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