Boards, Joists & Railing
Last reviewed: May 2026
Calculate exact material quantities for deck projects: decking boards, joists, beams, posts, footings, railing, and hardware. A deck involves more components than most DIYers expect — accurate planning prevents multiple trips to the lumberyard and ensures structural safety.1
| Deck Size | Sq Ft | Deck Boards (12ft) | Joists (16" OC) | Posts |
|---|---|---|---|---|
| 10×12 | 120 | 22 | 10 | 4–6 |
| 12×16 | 192 | 32 | 13 | 6–8 |
| 14×20 | 280 | 46 | 16 | 8–10 |
| 16×24 | 384 | 62 | 19 | 10–12 |
| Material | $/sq ft (material) | $/sq ft (installed) | Lifespan |
|---|---|---|---|
| Pressure-treated pine | $2–$5 | $15–$25 | 10–15 yrs |
| Cedar/redwood | $5–$10 | $20–$35 | 15–20 yrs |
| Composite (Trex, TimberTech) | $8–$15 | $25–$45 | 25–50 yrs |
| Hardwood (ipe) | $10–$25 | $35–$60 | 40–75 yrs |
Deck material selection balances upfront cost, maintenance requirements, and longevity. Pressure-treated pine ($2-5/sq ft for materials) is the budget standard: readily available, easy to work with, and lasting 15-20 years with annual sealing or staining. Cedar ($4-8/sq ft) is naturally rot and insect resistant with a beautiful grain, lasting 15-25 years but requiring periodic sealing to prevent graying. Composite decking ($6-12/sq ft for materials) uses a wood-fiber and plastic blend that never rots, splinters, or needs staining, lasting 25-50 years with just soap-and-water cleaning. Premium brands like Trex Transcend and TimberTech Azek offer realistic wood-grain textures and fade/stain warranties. PVC decking ($8-14/sq ft) contains no wood fiber, making it completely moisture-proof — ideal for pool surrounds and coastal environments. Tropical hardwoods like ipe ($10-20/sq ft) offer stunning aesthetics and 40-75 year lifespans but require specialized tools and fasteners. For a typical 300 sq ft deck, materials alone range from $900 (pressure-treated) to $6,000 (ipe), with composite averaging $2,400-3,600.
A deck's structural integrity depends on properly sized framing members. Joists (typically 2×8 or 2×10 pressure-treated lumber) support the decking surface: spacing determines the maximum span between beams. At 16-inch centers, a 2×8 spans up to 10.5 feet; a 2×10 spans up to 13.5 feet. Beams (doubled 2×10 or 2×12, or engineered lumber) span between posts and support the joists: a doubled 2×10 beam can span 8 feet between 6×6 posts. Posts (typically 6×6 pressure-treated, rated for ground contact) transfer the entire deck's weight to concrete footings. Footing size depends on soil bearing capacity and tributary load: in typical soil, a 12-inch diameter footing supports approximately 3,000 lbs, adequate for most residential deck posts. Ledger boards (2×10 or 2×12 bolted to the house) connect the deck to the home's rim joist using 1/2-inch lag bolts or through-bolts at 16-inch spacing — improper ledger attachment is the leading cause of deck collapse and building code inspectors scrutinize this connection closely.
Nearly all jurisdictions require permits for decks over 200 sq ft or those more than 30 inches above grade. Code requirements include: minimum footing depth below frost line (24-48 inches in northern climates), maximum guardrail opening spacing (4 inches — the "sphere test" ensures a 4-inch sphere can't pass through), guardrail height (36 inches for decks under 30 inches high, 42 inches for higher decks), stair riser height (7-3/4 inches maximum), and stair tread depth (10 inches minimum). Structural fastener requirements have tightened significantly: modern codes require specific joist hangers (Simpson Strong-Tie or equivalent), structural screws rated for treated lumber (standard screws corrode in ACQ-treated wood), and flashing at the ledger-to-house connection. Failing to pull a permit creates liability exposure: if someone is injured on an unpermitted deck, your homeowner's insurance may deny the claim, and unpermitted structures can complicate home sales during buyer inspections.
Total deck cost combines materials, labor, and miscellaneous items. For a 16×20 (320 sq ft) composite deck, 4 feet above grade with stairs and railing: decking materials $2,500-3,200, framing lumber $800-1,200, concrete footings $200-400, fasteners and hardware $300-500, railing system $1,500-3,000, stairs $400-800. Total materials: $5,700-9,100. Professional labor typically equals or exceeds material cost: $5,000-10,000 for a deck this size, bringing the total installed price to $10,700-19,100 ($33-60/sq ft). DIY construction saves the labor cost but requires 4-6 weekends of work for a capable homeowner. Key variables that increase cost: height above grade (taller posts, more complex stairs), multiple levels, curved edges, built-in benches or planters, electrical for lighting, and permits with engineering requirements. Budget an additional 15-20% contingency for unexpected issues like rocky soil requiring different footing approaches or lumber prices increasing between planning and purchase.
Deck maintenance requirements vary dramatically by material. Pressure-treated wood needs power washing and resealing or staining every 1-2 years ($0.50-1.50/sq ft per application, or $150-480 annually for a 320 sq ft deck). Skipping maintenance leads to splitting, warping, and premature decay — a $3,000 deck that should last 20 years may fail in 8-10 without care. Cedar requires similar maintenance but tolerates moisture better between treatments. Composite decking needs only annual cleaning with soap and water or a gentle pressure wash — no staining, sealing, or painting ever. Over a 25-year lifespan, a composite deck's total cost (higher materials, near-zero maintenance) is typically 20-30% less than a wood deck's total cost (lower materials, $4,000-12,000 in cumulative maintenance). All decking benefits from basic habits: sweep leaves and debris promptly (trapped moisture accelerates decay), keep grills on protective mats, move planters periodically to prevent moisture damage underneath, and clear snow with plastic shovels rather than metal ones that scratch the surface.
Deck material selection balances upfront cost, maintenance requirements, and longevity. Pressure-treated pine ($2-5/sq ft for materials) is the budget standard: readily available, easy to work with, and lasting 15-20 years with annual sealing or staining. Cedar ($4-8/sq ft) is naturally rot and insect resistant with a beautiful grain, lasting 15-25 years but requiring periodic sealing to prevent graying. Composite decking ($6-12/sq ft for materials) uses a wood-fiber and plastic blend that never rots, splinters, or needs staining, lasting 25-50 years with just soap-and-water cleaning. Premium brands like Trex Transcend and TimberTech Azek offer realistic wood-grain textures and fade/stain warranties. PVC decking ($8-14/sq ft) contains no wood fiber, making it completely moisture-proof — ideal for pool surrounds and coastal environments. Tropical hardwoods like ipe ($10-20/sq ft) offer stunning aesthetics and 40-75 year lifespans but require specialized tools and fasteners. For a typical 300 sq ft deck, materials alone range from $900 (pressure-treated) to $6,000 (ipe), with composite averaging $2,400-3,600.
A deck's structural integrity depends on properly sized framing members. Joists (typically 2×8 or 2×10 pressure-treated lumber) support the decking surface: spacing determines the maximum span between beams. At 16-inch centers, a 2×8 spans up to 10.5 feet; a 2×10 spans up to 13.5 feet. Beams (doubled 2×10 or 2×12, or engineered lumber) span between posts and support the joists: a doubled 2×10 beam can span 8 feet between 6×6 posts. Posts (typically 6×6 pressure-treated, rated for ground contact) transfer the entire deck's weight to concrete footings. Footing size depends on soil bearing capacity and tributary load: in typical soil, a 12-inch diameter footing supports approximately 3,000 lbs, adequate for most residential deck posts. Ledger boards (2×10 or 2×12 bolted to the house) connect the deck to the home's rim joist using 1/2-inch lag bolts or through-bolts at 16-inch spacing — improper ledger attachment is the leading cause of deck collapse and building code inspectors scrutinize this connection closely.
Nearly all jurisdictions require permits for decks over 200 sq ft or those more than 30 inches above grade. Code requirements include: minimum footing depth below frost line (24-48 inches in northern climates), maximum guardrail opening spacing (4 inches — the "sphere test" ensures a 4-inch sphere can't pass through), guardrail height (36 inches for decks under 30 inches high, 42 inches for higher decks), stair riser height (7-3/4 inches maximum), and stair tread depth (10 inches minimum). Structural fastener requirements have tightened significantly: modern codes require specific joist hangers (Simpson Strong-Tie or equivalent), structural screws rated for treated lumber (standard screws corrode in ACQ-treated wood), and flashing at the ledger-to-house connection. Failing to pull a permit creates liability exposure: if someone is injured on an unpermitted deck, your homeowner's insurance may deny the claim, and unpermitted structures can complicate home sales during buyer inspections.
Total deck cost combines materials, labor, and miscellaneous items. For a 16×20 (320 sq ft) composite deck, 4 feet above grade with stairs and railing: decking materials $2,500-3,200, framing lumber $800-1,200, concrete footings $200-400, fasteners and hardware $300-500, railing system $1,500-3,000, stairs $400-800. Total materials: $5,700-9,100. Professional labor typically equals or exceeds material cost: $5,000-10,000 for a deck this size, bringing the total installed price to $10,700-19,100 ($33-60/sq ft). DIY construction saves the labor cost but requires 4-6 weekends of work for a capable homeowner. Key variables that increase cost: height above grade (taller posts, more complex stairs), multiple levels, curved edges, built-in benches or planters, electrical for lighting, and permits with engineering requirements. Budget an additional 15-20% contingency for unexpected issues like rocky soil requiring different footing approaches or lumber prices increasing between planning and purchase.
Deck maintenance requirements vary dramatically by material. Pressure-treated wood needs power washing and resealing or staining every 1-2 years ($0.50-1.50/sq ft per application, or $150-480 annually for a 320 sq ft deck). Skipping maintenance leads to splitting, warping, and premature decay — a $3,000 deck that should last 20 years may fail in 8-10 without care. Cedar requires similar maintenance but tolerates moisture better between treatments. Composite decking needs only annual cleaning with soap and water or a gentle pressure wash — no staining, sealing, or painting ever. Over a 25-year lifespan, a composite deck's total cost (higher materials, near-zero maintenance) is typically 20-30% less than a wood deck's total cost (lower materials, $4,000-12,000 in cumulative maintenance). All decking benefits from basic habits: sweep leaves and debris promptly (trapped moisture accelerates decay), keep grills on protective mats, move planters periodically to prevent moisture damage underneath, and clear snow with plastic shovels rather than metal ones that scratch the surface.
Deck material selection balances upfront cost, maintenance requirements, and longevity. Pressure-treated pine ($2-5/sq ft for materials) is the budget standard: readily available, easy to work with, and lasting 15-20 years with annual sealing or staining. Cedar ($4-8/sq ft) is naturally rot and insect resistant with a beautiful grain, lasting 15-25 years but requiring periodic sealing to prevent graying. Composite decking ($6-12/sq ft for materials) uses a wood-fiber and plastic blend that never rots, splinters, or needs staining, lasting 25-50 years with just soap-and-water cleaning. Premium brands like Trex Transcend and TimberTech Azek offer realistic wood-grain textures and fade/stain warranties. PVC decking ($8-14/sq ft) contains no wood fiber, making it completely moisture-proof — ideal for pool surrounds and coastal environments. Tropical hardwoods like ipe ($10-20/sq ft) offer stunning aesthetics and 40-75 year lifespans but require specialized tools and fasteners. For a typical 300 sq ft deck, materials alone range from $900 (pressure-treated) to $6,000 (ipe), with composite averaging $2,400-3,600.
A deck's structural integrity depends on properly sized framing members. Joists (typically 2×8 or 2×10 pressure-treated lumber) support the decking surface: spacing determines the maximum span between beams. At 16-inch centers, a 2×8 spans up to 10.5 feet; a 2×10 spans up to 13.5 feet. Beams (doubled 2×10 or 2×12, or engineered lumber) span between posts and support the joists: a doubled 2×10 beam can span 8 feet between 6×6 posts. Posts (typically 6×6 pressure-treated, rated for ground contact) transfer the entire deck's weight to concrete footings. Footing size depends on soil bearing capacity and tributary load: in typical soil, a 12-inch diameter footing supports approximately 3,000 lbs, adequate for most residential deck posts. Ledger boards (2×10 or 2×12 bolted to the house) connect the deck to the home's rim joist using 1/2-inch lag bolts or through-bolts at 16-inch spacing — improper ledger attachment is the leading cause of deck collapse and building code inspectors scrutinize this connection closely.
Nearly all jurisdictions require permits for decks over 200 sq ft or those more than 30 inches above grade. Code requirements include: minimum footing depth below frost line (24-48 inches in northern climates), maximum guardrail opening spacing (4 inches — the "sphere test" ensures a 4-inch sphere can't pass through), guardrail height (36 inches for decks under 30 inches high, 42 inches for higher decks), stair riser height (7-3/4 inches maximum), and stair tread depth (10 inches minimum). Structural fastener requirements have tightened significantly: modern codes require specific joist hangers (Simpson Strong-Tie or equivalent), structural screws rated for treated lumber (standard screws corrode in ACQ-treated wood), and flashing at the ledger-to-house connection. Failing to pull a permit creates liability exposure: if someone is injured on an unpermitted deck, your homeowner's insurance may deny the claim, and unpermitted structures can complicate home sales during buyer inspections.
Total deck cost combines materials, labor, and miscellaneous items. For a 16×20 (320 sq ft) composite deck, 4 feet above grade with stairs and railing: decking materials $2,500-3,200, framing lumber $800-1,200, concrete footings $200-400, fasteners and hardware $300-500, railing system $1,500-3,000, stairs $400-800. Total materials: $5,700-9,100. Professional labor typically equals or exceeds material cost: $5,000-10,000 for a deck this size, bringing the total installed price to $10,700-19,100 ($33-60/sq ft). DIY construction saves the labor cost but requires 4-6 weekends of work for a capable homeowner. Key variables that increase cost: height above grade (taller posts, more complex stairs), multiple levels, curved edges, built-in benches or planters, electrical for lighting, and permits with engineering requirements. Budget an additional 15-20% contingency for unexpected issues like rocky soil requiring different footing approaches or lumber prices increasing between planning and purchase.
Deck maintenance requirements vary dramatically by material. Pressure-treated wood needs power washing and resealing or staining every 1-2 years ($0.50-1.50/sq ft per application, or $150-480 annually for a 320 sq ft deck). Skipping maintenance leads to splitting, warping, and premature decay — a $3,000 deck that should last 20 years may fail in 8-10 without care. Cedar requires similar maintenance but tolerates moisture better between treatments. Composite decking needs only annual cleaning with soap and water or a gentle pressure wash — no staining, sealing, or painting ever. Over a 25-year lifespan, a composite deck's total cost (higher materials, near-zero maintenance) is typically 20-30% less than a wood deck's total cost (lower materials, $4,000-12,000 in cumulative maintenance). All decking benefits from basic habits: sweep leaves and debris promptly (trapped moisture accelerates decay), keep grills on protective mats, move planters periodically to prevent moisture damage underneath, and clear snow with plastic shovels rather than metal ones that scratch the surface.
Deck material selection balances upfront cost, maintenance requirements, and longevity. Pressure-treated pine ($2-5/sq ft for materials) is the budget standard: readily available, easy to work with, and lasting 15-20 years with annual sealing or staining. Cedar ($4-8/sq ft) is naturally rot and insect resistant with a beautiful grain, lasting 15-25 years but requiring periodic sealing to prevent graying. Composite decking ($6-12/sq ft for materials) uses a wood-fiber and plastic blend that never rots, splinters, or needs staining, lasting 25-50 years with just soap-and-water cleaning. Premium brands like Trex Transcend and TimberTech Azek offer realistic wood-grain textures and fade/stain warranties. PVC decking ($8-14/sq ft) contains no wood fiber, making it completely moisture-proof — ideal for pool surrounds and coastal environments. Tropical hardwoods like ipe ($10-20/sq ft) offer stunning aesthetics and 40-75 year lifespans but require specialized tools and fasteners. For a typical 300 sq ft deck, materials alone range from $900 (pressure-treated) to $6,000 (ipe), with composite averaging $2,400-3,600.
A deck's structural integrity depends on properly sized framing members. Joists (typically 2×8 or 2×10 pressure-treated lumber) support the decking surface: spacing determines the maximum span between beams. At 16-inch centers, a 2×8 spans up to 10.5 feet; a 2×10 spans up to 13.5 feet. Beams (doubled 2×10 or 2×12, or engineered lumber) span between posts and support the joists: a doubled 2×10 beam can span 8 feet between 6×6 posts. Posts (typically 6×6 pressure-treated, rated for ground contact) transfer the entire deck's weight to concrete footings. Footing size depends on soil bearing capacity and tributary load: in typical soil, a 12-inch diameter footing supports approximately 3,000 lbs, adequate for most residential deck posts. Ledger boards (2×10 or 2×12 bolted to the house) connect the deck to the home's rim joist using 1/2-inch lag bolts or through-bolts at 16-inch spacing — improper ledger attachment is the leading cause of deck collapse and building code inspectors scrutinize this connection closely.
Nearly all jurisdictions require permits for decks over 200 sq ft or those more than 30 inches above grade. Code requirements include: minimum footing depth below frost line (24-48 inches in northern climates), maximum guardrail opening spacing (4 inches — the "sphere test" ensures a 4-inch sphere can't pass through), guardrail height (36 inches for decks under 30 inches high, 42 inches for higher decks), stair riser height (7-3/4 inches maximum), and stair tread depth (10 inches minimum). Structural fastener requirements have tightened significantly: modern codes require specific joist hangers (Simpson Strong-Tie or equivalent), structural screws rated for treated lumber (standard screws corrode in ACQ-treated wood), and flashing at the ledger-to-house connection. Failing to pull a permit creates liability exposure: if someone is injured on an unpermitted deck, your homeowner's insurance may deny the claim, and unpermitted structures can complicate home sales during buyer inspections.
Total deck cost combines materials, labor, and miscellaneous items. For a 16×20 (320 sq ft) composite deck, 4 feet above grade with stairs and railing: decking materials $2,500-3,200, framing lumber $800-1,200, concrete footings $200-400, fasteners and hardware $300-500, railing system $1,500-3,000, stairs $400-800. Total materials: $5,700-9,100. Professional labor typically equals or exceeds material cost: $5,000-10,000 for a deck this size, bringing the total installed price to $10,700-19,100 ($33-60/sq ft). DIY construction saves the labor cost but requires 4-6 weekends of work for a capable homeowner. Key variables that increase cost: height above grade (taller posts, more complex stairs), multiple levels, curved edges, built-in benches or planters, electrical for lighting, and permits with engineering requirements. Budget an additional 15-20% contingency for unexpected issues like rocky soil requiring different footing approaches or lumber prices increasing between planning and purchase.
Deck maintenance requirements vary dramatically by material. Pressure-treated wood needs power washing and resealing or staining every 1-2 years ($0.50-1.50/sq ft per application, or $150-480 annually for a 320 sq ft deck). Skipping maintenance leads to splitting, warping, and premature decay — a $3,000 deck that should last 20 years may fail in 8-10 without care. Cedar requires similar maintenance but tolerates moisture better between treatments. Composite decking needs only annual cleaning with soap and water or a gentle pressure wash — no staining, sealing, or painting ever. Over a 25-year lifespan, a composite deck's total cost (higher materials, near-zero maintenance) is typically 20-30% less than a wood deck's total cost (lower materials, $4,000-12,000 in cumulative maintenance). All decking benefits from basic habits: sweep leaves and debris promptly (trapped moisture accelerates decay), keep grills on protective mats, move planters periodically to prevent moisture damage underneath, and clear snow with plastic shovels rather than metal ones that scratch the surface.
Deck material selection balances upfront cost, maintenance requirements, and longevity. Pressure-treated pine ($2-5/sq ft for materials) is the budget standard: readily available, easy to work with, and lasting 15-20 years with annual sealing or staining. Cedar ($4-8/sq ft) is naturally rot and insect resistant with a beautiful grain, lasting 15-25 years but requiring periodic sealing to prevent graying. Composite decking ($6-12/sq ft for materials) uses a wood-fiber and plastic blend that never rots, splinters, or needs staining, lasting 25-50 years with just soap-and-water cleaning. Premium brands like Trex Transcend and TimberTech Azek offer realistic wood-grain textures and fade/stain warranties. PVC decking ($8-14/sq ft) contains no wood fiber, making it completely moisture-proof — ideal for pool surrounds and coastal environments. Tropical hardwoods like ipe ($10-20/sq ft) offer stunning aesthetics and 40-75 year lifespans but require specialized tools and fasteners. For a typical 300 sq ft deck, materials alone range from $900 (pressure-treated) to $6,000 (ipe), with composite averaging $2,400-3,600.
A deck's structural integrity depends on properly sized framing members. Joists (typically 2×8 or 2×10 pressure-treated lumber) support the decking surface: spacing determines the maximum span between beams. At 16-inch centers, a 2×8 spans up to 10.5 feet; a 2×10 spans up to 13.5 feet. Beams (doubled 2×10 or 2×12, or engineered lumber) span between posts and support the joists: a doubled 2×10 beam can span 8 feet between 6×6 posts. Posts (typically 6×6 pressure-treated, rated for ground contact) transfer the entire deck's weight to concrete footings. Footing size depends on soil bearing capacity and tributary load: in typical soil, a 12-inch diameter footing supports approximately 3,000 lbs, adequate for most residential deck posts. Ledger boards (2×10 or 2×12 bolted to the house) connect the deck to the home's rim joist using 1/2-inch lag bolts or through-bolts at 16-inch spacing — improper ledger attachment is the leading cause of deck collapse and building code inspectors scrutinize this connection closely.
Nearly all jurisdictions require permits for decks over 200 sq ft or those more than 30 inches above grade. Code requirements include: minimum footing depth below frost line (24-48 inches in northern climates), maximum guardrail opening spacing (4 inches — the "sphere test" ensures a 4-inch sphere can't pass through), guardrail height (36 inches for decks under 30 inches high, 42 inches for higher decks), stair riser height (7-3/4 inches maximum), and stair tread depth (10 inches minimum). Structural fastener requirements have tightened significantly: modern codes require specific joist hangers (Simpson Strong-Tie or equivalent), structural screws rated for treated lumber (standard screws corrode in ACQ-treated wood), and flashing at the ledger-to-house connection. Failing to pull a permit creates liability exposure: if someone is injured on an unpermitted deck, your homeowner's insurance may deny the claim, and unpermitted structures can complicate home sales during buyer inspections.
Total deck cost combines materials, labor, and miscellaneous items. For a 16×20 (320 sq ft) composite deck, 4 feet above grade with stairs and railing: decking materials $2,500-3,200, framing lumber $800-1,200, concrete footings $200-400, fasteners and hardware $300-500, railing system $1,500-3,000, stairs $400-800. Total materials: $5,700-9,100. Professional labor typically equals or exceeds material cost: $5,000-10,000 for a deck this size, bringing the total installed price to $10,700-19,100 ($33-60/sq ft). DIY construction saves the labor cost but requires 4-6 weekends of work for a capable homeowner. Key variables that increase cost: height above grade (taller posts, more complex stairs), multiple levels, curved edges, built-in benches or planters, electrical for lighting, and permits with engineering requirements. Budget an additional 15-20% contingency for unexpected issues like rocky soil requiring different footing approaches or lumber prices increasing between planning and purchase.
Deck maintenance requirements vary dramatically by material. Pressure-treated wood needs power washing and resealing or staining every 1-2 years ($0.50-1.50/sq ft per application, or $150-480 annually for a 320 sq ft deck). Skipping maintenance leads to splitting, warping, and premature decay — a $3,000 deck that should last 20 years may fail in 8-10 without care. Cedar requires similar maintenance but tolerates moisture better between treatments. Composite decking needs only annual cleaning with soap and water or a gentle pressure wash — no staining, sealing, or painting ever. Over a 25-year lifespan, a composite deck's total cost (higher materials, near-zero maintenance) is typically 20-30% less than a wood deck's total cost (lower materials, $4,000-12,000 in cumulative maintenance). All decking benefits from basic habits: sweep leaves and debris promptly (trapped moisture accelerates decay), keep grills on protective mats, move planters periodically to prevent moisture damage underneath, and clear snow with plastic shovels rather than metal ones that scratch the surface.
→ Use 16" OC for wood, 12" for composite. Composite is heavier and needs closer support.
→ Set posts in concrete. Post footings must be below the frost line.
→ Add 10–15% waste. Cuts, defects, and warped boards.
→ Check local codes first. Setbacks, height limits, and railing requirements vary.
See also: Lumber · Concrete · Stair · Fence