Deck Inspection Guide for Home Inspectors: DCA 6 and More

Short answer: Inspect a deck from the bottom up: footings and posts, beams, joists and hangers, then the ledger and its flashing, the lateral connection, and only then the surface, guards and stairs. The common reference is the American Wood Council's DCA 6 guide, whose current edition is based on the 2015 IRC, so treat it as a benchmark rather than the code your jurisdiction adopted. Most serious failures start at the ledger or the guards, and your report should say plainly what you could not see.

Decks look simple, which is why so many are built badly and why so many inspectors give them a quick walk and a photo. A deck is a structure hanging off the side of a house, often over a patio where people stand. It deserves the same method as the rest of the inspection.

This guide covers what to check, what to call out, which references to use and where your inspection stops.

Why decks deserve their own method

InterNACHI's deck inspection material makes the case bluntly. It estimates that of 45 million existing decks, only 40% are completely safe, and states that about 90% of deck collapses resulted from the ledger separating from the house. It also notes that rail failures happen far more often than total collapses, and cause more injuries. The North American Deck and Railing Association (NADRA) said in a June 2017 press release that the US has roughly 40 million residential decks, and estimated that half are more than 25 years old.

Those are association estimates, not government data, and they do not agree exactly. The direction is the same: many decks are old, and the ledger and the guards are where people get hurt.

DCA 6: the common reference, with a caveat

Most inspectors and many building departments use the American Wood Council's Prescriptive Residential Wood Deck Construction Guide, known as DCA 6. The edition AWC currently offers is "Based on the 2015 International Residential Code," copyright 2018. We did not find an edition for a later IRC on AWC's site as of September 2026.

What that means for you:

• It is a construction guide, not an inspection standard. It describes how to build a prescriptive deck. You use it as a benchmark for what good construction looks like.
• Your jurisdiction may use a different code edition. DCA 6 itself says that where it differs from the IRC, "provisions of the IRC shall apply," and that all construction must be approved by the authority having jurisdiction.
• It has a limited scope. It applies to "single level residential wood decks that are attached to the house to resist lateral forces." It assumes deck length no greater than width and 6x6 minimum posts, excludes hot tubs and other large concentrated loads, and does not cover snow loads over 40 psf.

So you cite DCA 6 as a reference that explains why a condition matters, not as a code ruling. As with any home inspection, you are not the code official. Our guide to what home inspectors are not allowed to do covers the wider boundary.

Inspect from the bottom up

InterNACHI's guidance is to follow the order of construction: start underneath, and if the deck looks unsafe from below, do not walk out on it. Stop and report. It is a simple rule, and it keeps you off decks that should not carry you.

A working sequence:

1. Footings and posts.
2. Beams and post-to-beam connections.
3. Joists, hangers and blocking.
4. Ledger, fasteners and flashing.
5. Lateral connection to the house.
6. Decking.
7. Guards and guard posts.
8. Stairs, handrails, stair footings and lighting.

NADRA's free Deck Evaluation Guide for deck professionals follows a similar list: stairs, footings and supports, posts and columns, beams, joists, ledger boards, deck surfaces, handrail assemblies, guards and additional features.

Footings, posts and beams

DCA 6 wants footings on undisturbed soil at least 12 inches below the undisturbed ground surface or below the frost line, whichever is deeper. It also says footings closer than 5 feet to an exterior house foundation wall must bear at the same elevation as the house footing, and that footings should not sit over septic systems, utility lines or enclosed meters.

You usually cannot see footing depth. You can see:

• Posts sitting on the ground, on blocks, or on pads that have moved.
• Posts not centered on footings.
• Rot at the base of posts, and uncoated cut ends.
• Post anchors that are not galvanized or stainless.
• Beams fastened to the side of the post with no notch or post cap. DCA 6 prohibits attaching the beam to the side of the post without notching; it calls for a notch or an approved post cap.
• Missing diagonal bracing at tall corner posts. DCA 6 calls for bracing parallel to the beam at each corner post greater than 2 feet tall.
• Beam sag. Sighting along the bottom edge is often easier than using a level.

Joists, hangers and blocking

• Hangers. DCA 6 requires joist hangers at least 60% of the ledger or beam depth, from an approved manufacturer, corrosion resistant. Look for missing fasteners, wrong fastener types, and clip angles used in place of hangers, which DCA 6 does not allow for joists.
• Joists framing into both sides of one beam. DCA 6 does not allow joists from opposite sides of the same beam.
• Overhangs and cantilevers. Long joist overhangs past the beam, or beams overhanging posts, are worth noting where they look excessive.
• Decay. Probe where water sits: tops of joists under decking, joist ends at the rim, and anywhere near the ledger.

Ledger attachment

This is the connection that fails. Spend time here.

From outside you cannot confirm lag screw length or whether the tip passes the band joist. Say so. If you can see the band joist from a basement or crawlspace, look for fastener tips, water staining and decay, and report what you see.

InterNACHI offers a rule-of-thumb formula for ledger fastener spacing. It is a screening aid, not a design check, and a deck with far fewer fasteners than the spacing tables suggest deserves a recommendation for evaluation by a qualified deck contractor or engineer.

Lateral load connection

DCA 6 requires decks to be "positively anchored to the primary structure." Its prescriptive method uses hold-down tension devices in at least two locations within 2 feet of the edges of the deck, each with an allowable stress design capacity of not less than 1,500 lb. The wall must be sheathed with at least 3/8 inch wood structural panel sheathing, and the method is not for brick veneer.

In the field, look for the devices from below or from the basement or crawlspace. On older decks they are usually absent. Report their absence as an observation with its consequence, not as a code violation: the deck relies only on the ledger fasteners to resist being pulled away from the house.

Guards and stairs

Rail failures injure more people than full collapses, so give guards a push test and a close look.

Check treads for rot and deflection, and riser height and tread depth for consistency. Report uneven risers as a trip hazard.

Fasteners, connectors and corrosion

Treated lumber is corrosive to the wrong metal. DCA 6 requires:

• Screws, bolts, washers, nuts and nails in treated wood to be hot-dipped galvanized, stainless steel, silicon bronze or copper. Fasteners other than nails may also be mechanically zinc-coated to ASTM B 695, Class 55 minimum.
• Connectors such as hangers and post anchors to be galvanized or stainless.
• Stainless steel grade 304 or 316 for fasteners and connectors exposed to salt water or within 300 feet of a saltwater shoreline.
• Fasteners and connectors of the same corrosion-resistant material.
• Flashing that is corrosion-resistant metal at least 0.019 inch thick or approved non-metallic material, with no aluminum in direct contact with copper-treated lumber.

In the field, look for rust staining, heads that have lost section, flaking coatings on hangers, electro-plated screws in treated lumber, and mixed metals. Near the coast, corrosion is often the headline finding.

Typical failure points, in one list

Writing deck findings

Deck findings get read by the client, the agent and a deck contractor pricing the repair. Write them so each reader gets what they need.

• Name the component and location. "Ledger at the east wall, between the second and third joists from the north end."
• Describe what you saw. "Ledger fastened with nails only; no lag screws or bolts observed; no flashing observed above the ledger."
• Say why it matters. "The ledger connection supports the deck at the house. Inadequate fastening can allow the deck to pull away from the house."
• Recommend. "Evaluation and correction by a qualified deck contractor or engineer."
• Photo attached to the finding.

Mark safety items clearly and put them near the top. More on wording is in how to write defect comments that hold up.

In Binsr, you can build a deck section, or a standalone deck template, in the order above, with findings, severity levels and photos that attach to the individual finding. If you sell deck evaluations as a separate service, one inspection can carry the main report and a separate deck report, each with its own template.

Limitations to state

Your deck inspection is visual. State the limits in the report and the agreement:

• You did not determine code compliance or the code edition that applies.
• You did not verify footing depth, fastener length or penetration, or the capacity of the band joist behind the ledger.
• You did not remove decking, skirting or finishes, or perform load testing.
• Areas you could not reach (low clearance, enclosed undersides, snow cover) are listed as not inspected.
• If you did not walk onto the deck because it looked unsafe from below, say so and why.

In Texas, as of November 2026, decks are reported under section I.K, "Porches, Balconies, Decks, and Carports," of the TREC REI 7-6 form. TREC's November 9, 2026 meeting agenda included proposing amendments to the inspection standards and the report form, so check the current form if TREC adopts a revision. See our TREC report guide.

Pricing deck inspections

Inside a standard home inspection, the deck is part of the job, and your base fee should reflect the time it takes to do it properly. As a standalone service, such as a deck evaluation for an owner or a new construction deck check, price it from your own time on site, drive time, report time and liability. The method is in how to price ancillary inspection services. On new builds, the deck ledger flashing is worth photographing at the pre-drywall inspection, and the finished deck is worth a close look at the 11-month warranty inspection.

Frequently asked questions

Keep reading

• New construction home inspections
• Pre-drywall inspection checklist and pricing
• 11-month builder warranty inspections
• How to price ancillary inspection services
• Write defect comments that hold up
• Home inspector tools

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