Decks collapse. Every year in the United States, deck collapses injure and kill people — usually during gatherings when load is high. The cause is almost always traceable to a specific construction failure: ledger board improperly attached to the house (not lag-bolted properly, or attached only to siding), joist hangers missing or the wrong type, rot at connections, inadequate post footings, or inadequate railings. Each of these is preventable. Each is common on deck-builder cut-rate work. The cost of hiring a substandard deck builder is measured not just in dollars but potentially in injury liability.
This guide is part of the Know Before You Hire series. At Home Services Co, our deck building service follows the full structural and code protocol described below.
The critical connection: the ledger. The ledger is the horizontal board attached to the house that supports one edge of the deck. It carries half or more of the deck's load. Failure of the ledger is the single most common cause of deck collapse. Proper ledger attachment: lag-bolted (or through-bolted) into the house's band joist (NOT into just the siding or sheathing), with proper lag bolt spacing per code, with flashing integrated between the ledger and the house to prevent water intrusion. Shortcut installations nail the ledger to the siding with standard nails — these fail over time as rot weakens the connection. Ask specifically how the ledger will be attached and flashed.
Joist hangers. Each joist connects to the ledger and to the outer beam via joist hangers — specific metal connectors sized for the joist dimension and rated for the load. Proper joist hangers are nailed with joist hanger nails (shorter, thicker than standard nails) filling every hole in the hanger. Shortcut installations use wrong-sized hangers, skip nails, or — shockingly — omit hangers entirely. Look at the hangers. If a significant number of hanger holes are empty of nails, the connection is not to code.
Post footings. The posts supporting the outer edge of the deck sit on concrete footings. Footings must extend below the frost line in freezing climates (typically 30-48 inches depending on region) and be sized adequately for the load. Shortcut footings are too shallow (frost heaves lift the post, deck tilts), inadequate diameter (load exceeds bearing capacity, footing settles), or pour-around-the-post style with no proper bearing surface. Real footings require excavation, inspection (permit-required in most jurisdictions), and proper pour.
Railings. Deck railings are a code-regulated safety element. Required on decks over 30 inches above grade. Must meet specific height (typically 36-42 inches), spacing (no openings larger than 4 inches through which a 4-inch sphere can pass), and load resistance (typically 200 lbs applied at any point). Railings that are too short, too weakly attached, or have wider spacing than code are the safety failure waiting to hurt someone. See does this job need a permit — deck railings are always a permit-regulated element.
Permits are non-negotiable. Decks are one of the most consistently permit-required residential projects. Nearly every jurisdiction requires permit and inspection. The inspection process is specifically designed to catch the failure modes described above — ledger attachment, joist hangers, footings, railings. Skipping the permit means skipping the structural inspection that would have caught the failure. A deck builder who offers to 'save you the permit fee' is a builder who doesn't want the inspector verifying their work.
Material options. Pressure-treated pine: budget standard, 10-15 year lifespan, requires staining/sealing. Cedar: premium, aromatic, 15-25 year lifespan with maintenance. Composite (Trex, TimberTech): moderate to premium cost, 25+ year warranty, very low maintenance. PVC decking: premium cost, essentially zero maintenance. Hardwood (ipe, mahogany): premium cost, 40+ year lifespan, heaviest to install. Each has specific installation requirements — composite requires specific fastener patterns, hardwood requires pre-drilling, pressure-treated needs specific flashing at the ledger due to corrosive preservatives.
Corrosion-resistant fasteners. Pressure-treated wood (since post-CCA ACQ treatments became standard) is corrosive to standard steel fasteners. Deck fasteners, joist hangers, and lag bolts in contact with pressure-treated wood must be hot-dipped galvanized or stainless steel. Standard fasteners corrode rapidly and fail within years. Verify the fastener spec on the quote.
Red flag #1: proposing to attach the ledger with nails to the siding. Immediate disqualification. This is the structural failure mode that causes collapses.
Red flag #2: no joist hangers in the scope. Some shortcut builders frame decks with just nails at the joist-to-ledger connections. This is not to code and is structurally inadequate.
Red flag #3: post-hole footings instead of frost-line concrete footings in cold climates. Precast pads sitting on the surface work in some climates for small structures, but not in freezing climates where frost heave shifts them every winter.
Red flag #4: railings under 36 inches in any application where they're required. Code violation, safety risk.
Red flag #5: no permit in the scope. Means skipping inspection. Skipping inspection means no external verification of structural integrity. Walk.
Red flag #6: standard fasteners in pressure-treated applications. Corrosion failure in a few years.
Pricing reality. Pressure-treated deck (typical 300 sq ft with stairs and railings): $6,000-$12,000. Cedar: $10,000-$18,000. Composite: $12,000-$25,000. PVC: $15,000-$30,000. Hardwood: $20,000-$40,000+. Second-story decks or complex designs run higher. These include all structural work, decking, railings, stairs, and permits. Demolition of existing deck typically adds $1,500-$3,500.
Inspection during build. The permit process includes inspections at specific stages: footings (before pouring concrete), framing (before decking is laid), and final (completed deck with railings). These inspections are your protection. Insist the deck builder schedules them and that you see the signed inspection cards before paying for each stage.
Stairs. Deck stairs have specific code requirements: uniform rise and run (no variation between steps), graspable handrails, adequate tread depth, no openings larger than code allows. Stair design is a common failure point — varying step heights cause trips and falls. Inspect the stairs for uniformity.
Flashing at the ledger. The connection where the deck ledger meets the house must be flashed to prevent water from getting behind the siding and causing rot. Proper flashing sequence: the house's weather-resistive barrier, then a Z-flashing or other cap flashing, then the ledger. Water hits the flashing and drains away rather than entering the wall assembly. Improperly flashed ledgers lead to wall rot behind the deck — invisible until catastrophic.
Maintenance. Wood decks need regular cleaning, sanding, and re-staining (every 2-3 years). Composite and PVC need periodic washing. All decks need annual inspection of structural connections — check the ledger for rot signs, joist hangers for corrosion, fasteners for integrity. A five-minute annual inspection catches early problems. See when to reseal your deck.
Warranty. Manufacturer warranty on composite and PVC decking is significant (often 25 years). Workmanship warranty on the build typically 1-5 years. Structural warranty (on the framing) should match the material. See warranty vs guarantee.
The summary. Permits and inspections are non-negotiable. Proper ledger attachment with through-bolts and flashing. Joist hangers with all nails filled. Frost-line footings. Code-compliant railings. Corrosion-resistant fasteners. Inspections verify the hidden connections you can't see after the decking is down.
At Home Services Co, our deck building service follows full code with permits, proper ledger attachment, hanger specs, and inspections. Related: concrete contractor, fence installer, landscaper, when to reseal your deck, pricing, book, or the full series.