The freestanding low-platform deck estimator that does the permit + ventilation + foundation math first. Three foundation systems compete head-to-head — Dek-Block pre-cast piers (DIY classic, $8/each), Pylex/Krinner ground screws ($45/each, no-dig), or 12″ poured concrete piers ($35 + labor, permanent). Auto-flags IRC R105.2 permit exemption when your dimensions qualify (≤200 sqft + ≤30″ + no ledger). The killer feature is the ventilation gap check — at least 4″ of air space below the joist underside is required to prevent rot, and the math automatically detects when your deck height + joist size leaves insufficient clearance. 4 surface materials, 3 patterns, 4 vapor-barrier options, optional perimeter built-in bench. 2026-Q1 retail. Floating decks bypass frost-depth footing requirements in most jurisdictions.
Joist depth 7.25″ + 1.5″ post cap = 8.75″ of vertical fill. With 8″ deck height, you're leaving 0″ for air movement under the joists. Joists rot in 8-12 years with insufficient ventilation, even pressure-treated. Either raise the deck or switch to a smaller joist size.
Your dimensions qualify for the standard IRC R105.2 work-exempt threshold — most jurisdictions don't require a permit. ALWAYS verify with your local building department before starting (HOAs + historic districts + floodplains may have stricter local amendments).
Prevents weed growth + light moisture barrier — $0.18/sqft. Standard for dek-block + ground-screw foundations.
Pricing 2026-Q1 retail · regional labor multiplier baked in. Ground-level decks the cheapest tier per sqft because no ledger, no full footings, no stairs, no guard.
Dek-Block (DIY classic) vs ground screw (no-dig) vs poured pier (permanent). Same surface, same framing, same region. Switch by clicking a tile.
Official IRC code text on the permit exemption thresholds (200 sqft, 30″, no ledger).
Closely related — covers the broader floating-deck category with more surface options.
This calc is sized for true ground-level decks. For elevated decks with proper footings + ledger + stairs + guards, use the Deck Cost Calculator.
Estimates use 2026-Q1 national-median pricing. Always verify permit requirements with your local building department — IRC R105.2 exemption is the default but HOAs + historic districts may have stricter rules. DeckMath is not a substitute for a licensed builder or local permit authority.
How to use
Ground-level decks have no ledger attached to the house and sit 30″ or less above grade at the highest point. If either is false, this isn't a ground-level deck — switch to the Deck Cost Calculator or Multi-Level Deck Calculator. Decks above 30″ require IRC R312 guardrail, which changes the whole framing approach.
Dek-Block piers ($8.50 each) sit on compacted gravel — fastest, cheapest, DIY-friendly, only viable up to ~200 sqft. Ground screws ($45 each, Pylex/Krinner) replace dig-and-pour with a driven helical anchor — fast on uneven sites, works in any soil except solid rock. Poured concrete piers ($35 + labor) are 12″ deep sonotube-formed piers with post anchors — permanent, scales to any size, only foundation suitable for decks > 200 sqft.
Pressure-treated 5/4 deck board ($3.20/sqft) is the cheapest and most widely stocked — needs re-seal every 1-2 years. Western red cedar ($5.80/sqft) is the warm-look choice — annual oil for 25-30 yr life. Capped composite ($7.50/sqft) is set-and-forget — 25-yr warranty, zero refinishing. Concrete pavers over a sleeper grid ($6.40/sqft) is a hybrid — fire-proof, zero maintenance, but heavier and limited to 24″ OC joist spacing.
Critical input — drives the ventilation gap check. Default 8″ is the most common ground-level deck height. At 4″ height with a 2×8 joist, you have effectively NO air gap below the joist (joist depth 7.25″ + 1.5″ post cap = 8.75″, which is more than the 4″ height — joist would sit ON the ground). Math is auto-checked. The calculator flags FAIL if gap is under 4″.
Landscape fabric ($0.18/sqft) is the standard pick — kills weeds + light moisture barrier. Crushed #57 stone over fabric ($0.85/sqft) gives better drainage on sloped or clay sites. Full concrete pad ($4.20/sqft) is overkill but eliminates rot risk entirely. 'None' (bare soil) is flagged as a warning — weeds and moisture rot joists in 3-5 years. Adding fabric later means lifting the deck.
Parallel pattern allows 16″ OC joist spacing (cheaper, fewer joists). Diagonal pattern forces 12″ OC (more joists, more cost). Picture-frame allows 16″ OC. Joist size: 2×6 spans up to 8.8 ft at 16″ OC, 2×8 spans up to 11.7 ft. If your deck width exceeds the joist's max span, calculator flags it — you either need a center beam (already included) or larger joists.
Most jurisdictions exempt ground-level decks under 200 sqft + 30″ + no ledger from building permits (IRC R105.2). Calculator auto-flags when your dimensions qualify. Always verify with your local building department — some HOA-restricted neighborhoods and historic districts have stricter local amendments.
Material guide
Three honest paths. Composite wins the 25-year math for most homeowners, wood wins on upfront cost, and PVC is unbeatable around water. Each card below answers in one glance — recalculate the bill of materials by clicking a brand in the picker above.
How we calculate
The Ground-Level Deck Calculator prices a freestanding low-platform deck across the three foundation systems people actually use: Dek-Block pre-cast piers ($8/each — DIY classic), Pylex / Krinner ground screws ($45/each — no digging), and 12″ poured concrete piers ($35 + labor — most permanent). Ground-level decks are special: with no ledger attached to the house and the walking surface ≤30″ above grade, most jurisdictions exempt them from a building permit entirely (under 200 sqft), and floating decks sidestep the frost-depth footing requirement that turns a $400 footing into a $1,200 footing in cold climates. The killer feature is the ventilation gap check — at least 4″ of air space below the joist underside is required to prevent rot. We auto-flag when your selected deck height + joist size produces less than 4″ of clearance. Four surfaces (PT, cedar, capped composite, concrete pavers over sleepers), three patterns (parallel, diagonal, picture-frame), four vapor-barrier options (landscape fabric, crushed gravel, concrete pad, or bare soil — flagged). Optional perimeter built-in bench. 2026-Q1 retail.
Foundation pricing reflects 2026-Q1 Home Depot retail (Dek-Block, Pylex ground screws) + national-median concrete pier installer rates. Permit-exemption logic per IRC 2021 R105.2 thresholds (200 sqft + 30″ + no ledger). Joist span tables from IRC 2021 R507.6 for PT southern pine #2. Ventilation gap rule (4″ min, 6″ preferred) from deck-industry best practice — IRC doesn't specify but rot research consistently shows accelerated decay below 4″ of air movement.
Dek-Block grid is 5 ft OC, ground-screw + poured-pier is 6 ft OC. A 14×10 deck on dek-block: ceil(10/5+1) × ceil(14/5+1) = 3 × 4 = 12 supports. Ground screws: 3 × 3 = 9 supports.
Air space between grade and joist underside. 2×8 joist (7.25″ depth) + 1.5″ post cap = 8.75″. Deck at 12″ above grade leaves 3.25″ gap — FAILS the 4″ minimum. Minimum-acceptable deck height with 2×8 joist + dek-block is ~13″ for 4″ gap, ~15″ for preferred 6″.
2×6 at 16″ OC spans 8.8 ft. 2×8 at 16″ OC spans 11.7 ft. 2×8 at 12″ OC spans 12.8 ft (gain from tighter spacing). Beyond max, you need a center beam (calculator adds one automatically for any width over 14 ft).
Standard IRC R105.2 exemption thresholds. Most US jurisdictions follow these. A 14×10 (140 sqft) deck at 8″ height with no ledger = EXEMPT. A 16×16 (256 sqft) at same height = permit required (over 200 sqft threshold).
Floating decks (dek-block + ground-screw) are not rigidly attached to a building, so seasonal frost heave is acceptable — the deck moves with the ground. Poured-pier foundations are rigidly framed and require either 12″ minimum depth (in most jurisdictions for low decks) or full frost depth (40-48″ in cold climates).
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