Which To Inspect First on a Bouncy Deck: Ledger vs Post vs Beam Sequencing Decision Tree

Why this matters

When a deck bounces, the temptation is to crawl under it and start poking at whatever is closest. That is backwards. The order in which you inspect the load path determines whether you find the dangerous defect before you spend an hour on a harmless one, and it determines whether you load a connection that is already failing while you are standing on it. The load path runs from decking to joists to beam to posts to footings, and laterally from the deck back into the house through the ledger. Two of those elements, the ledger and the posts/footings, are the ones that produce sudden collapse. The beam usually telegraphs distress before it lets go. So the inspection sequence is not "outside in" or "inside out," it is "most-catastrophic-first," and that means ledger, then posts and footings, then beam, then everything else.

Sequencing also saves the customer money. If you confirm a failed ledger in the first ten minutes, the rest of the inspection changes from "diagnose the bounce" to "scope the repair," and you do not bill for chasing joist deflection that is irrelevant once the deck has to be partially rebuilt anyway.

Symptom presentation

Before sequencing, read the bounce so you know what you are walking toward:

• Bounce worst near the house wall raises the ledger to the top of the queue immediately.
• Bounce with side-to-side sway points at posts, post-to-beam connection, or missing bracing.
• Bounce worst at the outboard edge / mid-span of the field points at the beam or joists.
• Visible lean of a post, or a post heel lifting off its footing is a footing/post finding that jumps the queue.

Quick checks

These are the reads that let you triage in the first pass:

1. Ledger gap and corrosion scan. Look along the entire ledger-to-house seam for any opening gap, rust streak below a lag, daylight, or flashing that has pulled. Push down hard within 2 ft of the wall and watch the seam.
2. Post plumb and bearing. Hold a level on two faces of each post. Check that the post sits fully on its footing pad with a code-compliant base connector, not toe-nailed or sitting on a buried block.
3. Footing check. Look for heave, settlement, cracking, or a post bearing on soil instead of a poured footing below frost depth.
4. Beam sight. Sight along the beam for sag, check for split or crushed bearing at the post tops, and confirm the beam is mechanically connected to the posts (positive connection, not just gravity bearing).

Isolation tree

Inspect in this fixed order. Do not skip ahead even if a later element looks suspicious, because an early failure changes the whole scope.

• Step 1 - Ledger. Is there any gap, rust, flashing failure, or movement at the house connection?
  • Yes -> This is your finding. Restrict load, scope the connection repair against IRC R507.9, and stop. The bounce is now secondary to a collapse risk.
  • No -> proceed to Step 2.
• Step 2 - Posts and footings. Are all posts plumb, fully bearing on footings below frost line, with positive base and cap connectors?
  • No (lean, lift, heave, missing connector) -> This is your finding. A post that is not plumb or not positively connected is a lateral-stability failure. Scope it before chasing flex.
  • Yes -> proceed to Step 3.
• Step 3 - Beam. Is the beam free of sag, splits, crushed bearing, and positively connected to posts and carrying joists with hangers/connectors?
  • No -> Beam-level finding. Confirm species/grade and span against DCA6.
  • Yes -> proceed to Step 4.
• Step 4 - Joists and decking. Only now investigate joist deflection and board span. By here you have cleared the catastrophic elements and the bounce is a stiffness comfort problem.

Confirming diagnosis

• Ledger: Confirm fastener type, size, spacing, penetration into band board, and presence of lateral-load hold-downs per IRC R507.9. Lags into siding/sheathing only, missing hold-downs, or corrosion confirm a connection failure.
• Posts/footings: Confirm footing depth below local frost line and bearing area per IRC R507.3. A post that has heaved is a footing-depth failure; a post that leans without heave is a base-connection or bracing failure.
• Beam: Confirm beam ply count, species, grade, and span against the DCA6 beam tables, and confirm positive post-to-beam connection. Crushed bearing at a post top confirms overload or undersized bearing.

Remediation

• Ledger: Re-fasten per the R507.9 schedule into the band board, add lateral hold-down devices, correct flashing. Structural priority.
• Posts/footings: Re-pour or extend footings below frost depth, plumb and reset posts with rated base connectors, add bracing or knee braces for lateral stability.
• Beam: Sister or replace per DCA6 span tables, add a post to shorten the span, install proper post caps.
• Joists/decking: Add blocking or a mid-span beam to kill residual bounce once the load path above is sound.

References

• IRC R507 (Decks) - ledger attachment R507.9, footing and post requirements R507.3, lateral-load connections.
• AWC DCA6, Prescriptive Residential Wood Deck Construction Guide - beam and joist span tables, connection details.
• ASTM D7032 - deck board span ratings (decking-level checks in Step 4).
• AWPA U1 - Use Category System for treated wood (relevant when posts/beams show rot at bearing).