Deck Building: Planning, Permits, and Construction
Plan and build a backyard deck from permit applications and material selection through framing, decking, railing, and finishing for years of outdoor enjoyment.
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Planning and Permits
Determine deck size, shape, and location
A 12x16-foot deck (192 sq ft) fits a table for 6 and a grill comfortably. Place the deck where it gets 4-6 hours of afternoon shade if possible. South-facing decks get the most sun exposure.
Check local building codes and setback requirements
Most jurisdictions require decks to sit 5-10 feet from property lines. Decks over 30 inches above grade almost always need a permit and railing. Call your local building department before starting any design work.
Call 811 to mark underground utilities
This free service marks gas, electric, water, and cable lines within 2-3 business days. Hitting a gas line while digging footings can cause explosions. Hitting a power line can be fatal. Always call before you dig.
Submit permit application with deck plans
Permit applications require a site plan showing the deck location, a framing plan, and a cross-section drawing. Permits cost $200-$800 depending on deck size. Approval takes 1-4 weeks.
Draw site plan with property lines and setbacks
Prepare framing plan with beam and joist spacing
Set a budget and order materials
Pressure-treated wood decking costs $15-$25 per sq ft installed. Composite decking runs $25-$45 per sq ft. A 200 sq ft deck in pressure-treated lumber costs $3,000-$5,000 in materials alone.
Foundation and Framing
Attach ledger board to the house
Use 1/2-inch lag bolts every 16 inches, staggered high and low. Install flashing above the ledger board to prevent water from entering the house. A poorly flashed ledger is the number one cause of deck-related water damage.
Dig and pour concrete footings
Footings must extend below the frost line — 36-48 inches in cold climates, 12-18 inches in warm ones. Each footing uses 2-4 bags of concrete mix at $5-$7 per 80-pound bag. Use a post hole digger or rent an auger ($50-$75/day).
Set posts and cut to height
Use 6x6 posts for decks over 4 feet high, 4x4 posts for lower decks. Set posts in post brackets on top of footings rather than burying them in concrete — this prevents rot and allows easy replacement.
Install beams on top of posts
A doubled 2x10 beam spans up to 8 feet between posts. A doubled 2x12 spans up to 10 feet. Always crown the beam (bow side up) and secure with through-bolts, not just nails.
Hang joists at 16-inch centers
Use 2x8 joists for spans up to 10 feet, 2x10 for spans up to 13 feet. Attach joists with galvanized joist hangers rated for the lumber size. Each hanger costs $2-$4 and requires 10-12 joist hanger nails.
Schedule and pass framing inspection
Most jurisdictions require a framing inspection before you cover joists with decking. The inspector checks post connections, joist spacing, beam sizing, and ledger attachment. Schedule 3-5 business days in advance.
Decking Installation
Install first deck board perfectly straight and square
The first board sets the alignment for every board after it. Measure from the house wall to the first board at both ends — they should be identical within 1/8 inch. Snap a chalk line as a guide.
Fasten deck boards with consistent spacing
Leave 1/8-inch gaps between boards for drainage and expansion. Use a 16d nail as a spacer. For composite decking, use hidden fasteners ($60-$80 per 100 sq ft) for a clean, screw-free surface.
Cut and trim deck boards at the perimeter
Let boards overhang the frame by 1-1.5 inches, then snap a chalk line and cut them all at once for a perfectly straight edge. Use a circular saw with a sharp, 40-tooth blade for clean cuts.
Install fascia boards around the frame
Fascia covers the exposed framing for a finished look. Use the same material as your decking for a consistent appearance. Pre-drill holes within 2 inches of board ends to prevent splitting.
Railings and Stairs
Install railing posts at 6-foot maximum spacing
Posts must be bolted through the rim joist with 1/2-inch carriage bolts. Surface-mounted post brackets ($15-$25 each) are easier than notching posts. Railing is required when the deck surface is 30+ inches above grade.
Attach top and bottom rails between posts
Top rail height must be 36 inches minimum for residential decks (42 inches in some jurisdictions). Use a level on every rail section. Pre-cut rail kits cost $30-$60 per 6-foot section.
Install balusters or infill panels
Balusters must be spaced so a 4-inch sphere cannot pass through — this is a safety code requirement to protect children. That means spacing balusters 3.5 inches apart maximum on center.
Build stairs with proper rise and run
Standard stair rise is 7-7.75 inches and tread depth is 10-11 inches. All steps must be the same height within 3/8 inch. Use a stair calculator to determine the number of steps needed for your deck height.
Finishing and Final Inspection
Apply stain or sealant to wood decking
Wait 2-4 weeks after construction for pressure-treated wood to dry before staining. Apply stain in temperatures between 50-90°F with no rain expected for 24 hours. One gallon covers 150-250 sq ft.
Add finishing details and accessories
Post caps ($5-$15 each) protect post tops from water damage. Solar post cap lights cost $15-$30 each and add ambiance without wiring. Stair lighting improves safety and costs $10-$20 per riser light.
Schedule and pass final building inspection
The final inspection covers railing height, baluster spacing, stair dimensions, structural connections, and flashing. Have your permit card posted visibly. Keep all inspection records for when you sell the home.
Frequently Asked Questions
How much does it cost to build a deck per square foot?
Pressure-treated wood decks cost $15-$25 per square foot for materials and $25-$50 installed. Composite decking (Trex, TimberTech) runs $30-$45 for materials and $50-$80 installed. A standard 16x20-foot (320 sq ft) deck costs $8,000-$16,000 for wood or $16,000-$25,000 for composite. Elevated decks over 4 feet high add 30-50% due to additional structural requirements.
Do I need a permit to build a deck?
Most jurisdictions require a permit for any attached deck or any freestanding deck over 200 square feet or 30 inches above grade. Permits cost $100-$1,000 depending on deck size and location. The permit process takes 1-4 weeks and requires a site plan, structural drawings, and footing details. Building without a permit can result in fines, required demolition, and complications when selling your home.
How long does pressure-treated wood last on a deck?
Pressure-treated pine decking lasts 15-20 years with regular sealing every 2-3 years. The structural framing (joists, beams, posts) lasts 25-30 years since it stays drier than the decking surface. Composite decking lasts 25-50 years with no sealing required, though it costs 2-3x more upfront. The biggest threat to treated wood is standing water that pools in joints and end grain, so proper drainage and spacing are critical.
What size footings do I need for a deck?
Most residential decks require concrete footings 12-24 inches in diameter and extending below the local frost line (12 inches in the South to 48+ inches in northern climates). A typical 16x20 deck needs 6-9 footings. Each footing supports 2,000-4,000 pounds depending on diameter. Your building department specifies exact requirements based on soil type, deck size, and local snow loads in the permit process.
Is composite decking worth the extra cost over wood?
Over a 25-year period, composite decking often costs less than wood when you factor in maintenance. A 320 sq ft wood deck needs re-staining every 2-3 years at $400-$800 per application, totaling $3,500-$7,000 in maintenance over 25 years. Composite needs only occasional soap-and-water cleaning. Composite also resists rot, insects, and splintering. The tradeoff is that composite gets hotter in direct sun (up to 35°F warmer than wood) and has a slightly different feel underfoot.