Existing Footing Reuse Verification Standard

Purpose

A footing decision made on a rebuild is buried the moment decking goes back down. Unlike a loose hanger, a bad footing gives no warning from above until a freeze cycle or the new load the job just added finds the weak point. This procedure exists so "we're building on the old footings" is reached by exposing, measuring, and testing the concrete, not by the fact that it has held a deck up so far, since past performance under the old load says nothing about the new load or about a code whose depth and bearing rules have since changed.

Scope

Covers evaluating an existing cast-in-place or precast deck footing for reuse under a new or rebuilt structure, from exposure through the reuse, augment, or reject decision and its record.

Does not cover assessing the rest of an existing deck's structure; the existing deck safety assessment SOP owns that. Does not cover laying out and pouring a new footing (the footing layout and inspection readiness SOP) or the hand technique of digging and placing concrete (the concrete footing excavation and pour technique article); this SOP hands off to both where a footing is replaced. Does not cover engineering or installing an added pier, which follows the engineer's own detail.

Roles and responsibilities

Procedure

1. Establish what the new work asks of this footing, treating any old record as a hypothesis, not an answer. Compute the new design's tributary load on each footing under review, at the 40 psf live plus 10 psf dead basis IRC Table R301.5 gives for decks, edition adopted, against what any surviving permit note implies for the original sizing. Acceptance: a written comparison stating whether the new footprint or an added feature increases the load. Wrong looks like treating this as only a condition question, when sound concrete can still be undersized for a bigger job than the one it was poured for. Stop rule: no comparison, no dig. No hazard yet.

2. Clear the excavation through the utility locate SOP before opening ground around or under the footing. Carry that ticket number forward into this record. Acceptance: a valid ticket, marks present, tolerance zone honored. Stop rule: no valid ticket, no digging. Hazard: a rebuild crew can hit a service that postdates the original deck, so any hole inside a mark's tolerance zone is opened by hand, never machine, and if a line is struck or you smell gas, everyone leaves on foot and upwind at once with nothing started, shut off, or touched, and the utility is called from a distance.

3. Fully expose the footing, not just the top few inches around the post. Excavate the full circumference down past the pour line to below its bottom edge on every reachable side. Acceptance: the complete side profile visible top to bottom. Wrong looks like a shallow ring cleared around the post, which hides an undersized or shallow pour. Stop rule: if exposing it would remove soil supporting a post still carrying the existing deck's load, stop and shore that post from an adjacent point first; that shore stays in place, checked at the start of each work session, until step 9's decision transfers the load to a new connection or a new pier, and only then comes out. Hazard: an open excavation beside a still-loaded footing is a collapse and fall risk, so barricade it and keep everyone clear until the load is off that soil, and if the face slumps or anyone is caught, stop digging immediately and call for emergency extraction rather than digging them out by hand.

4. Measure the footing's true diameter and its depth from current grade, at the narrowest section. A pour formed against native soil can flare; measure the narrowest cross-section, since that governs bearing area, with a straightedge and a dropped tape. Acceptance: a recorded minimum diameter and depth from today's grade to the underside. Wrong looks like measuring a flared top and calling that the bearing diameter. Stop rule: an irregular footing whose narrowest section cannot be identified is treated as inadequate pending further exposure, never estimated by eye.

5. Compare the measured depth against the frost depth and minimum your jurisdiction has adopted today, not the code in force when it was poured. Acceptance: depth at or below the current frost line and not less than 12 inches below undisturbed grade per IRC R403.1.4.1, edition adopted. Wrong looks like passing a shallow footing because it has not visibly heaved in twenty years, since heave is cyclical and a light historical load can mask a shallow footing until the season it does not. Stop rule: shallower than today's minimum does not get reused as sole support regardless of condition; it moves to step 9's augment-or-reject branch.

6. Inspect and sound the concrete for hidden failure, not just visible cracking. Look for spalling, map cracking, and rust-stained steel, then hammer-sound the surface for a hollow return, and probe any crack wider than a hairline with an awl under thumb pressure, checking whether the matrix crumbles. Acceptance: no map cracking, no hollow response, no crack admitting the awl past a shallow depth, no exposed corroding steel. Wrong looks like waving off a hairline crack without sounding around it, since it can be the tip of a freeze-thaw void underneath. Stop rule: any hollow response or crumbling matrix rejects the footing outright; failed concrete is replaced or piered independently, never augmented on itself. Hazard: sounding and probing releases dust that may carry respirable crystalline silica, so follow the dust-control method your shop's silica plan under 29 CFR 1926.1153 names, or defer breakout rather than chip it dry.

7. Identify and verify the post base connection, or its absence. Determine whether an anchored standoff base holds the post, whether it sits on wet-set concrete with no standoff, or whether nothing mechanical connects it at all, common on older decks. Acceptance: a positively identified connection type, and where a standoff base exists, confirmation it is unrotated, anchored, and holding the post's end grain clear of the concrete. Wrong looks like assuming a connection exists because the post looks attached from a step back. Stop rule: an absent or failed connection fails this footing for reuse as-is regardless of the concrete's condition; adding an approved base is a separate, schedulable step, not a substitute for this finding.

8. Check for movement: settlement, heave, or an undermined edge. Check the exposed top for level against its neighbors and a benchmark, and probe beneath every accessible edge with a rod for a void. Acceptance: level and plumb within the tolerance the post and beam framing standard requires for a new base, and no void at any probed edge. Wrong looks like reading an out-of-level footing as consistent with a yard's natural slope without probing it. Stop rule: any detected void moves that footing to replacement or an added pier, never backfilled and reused on partial bearing.

9. Make and record the decision, with sign-off where the finding is structural. Reach exactly one outcome per footing: Reuse as-is, Reuse with an added connection, Augment with an independent pier, or Reject and replace. Acceptance: one decision, its driving finding named, and a design professional's written sign-off for any Augment or Reject resting on a step 5, 6, or 8 finding. Wrong looks like a verbal "it's fine, build on it" with nothing written down. Stop rule: no framing loads a footing without a signed decision on file.

10. Protect the decision before backfilling. For Reuse or Reuse-with-added-connection, complete the connection first, then backfill and compact in layers, keeping new hardware clear of soil contact. For Reject, leave the hole open and covered per the footing layout SOP's protection standard until repour. Acceptance: backfill compacted in layers, or the hole covered with staked, weight-rated plywood if work pauses. Wrong looks like loose spoil shoveled back in one lift and tamped only at the top. Stop rule: framing does not proceed onto a reused footing until backfill is compacted, nor past a rejected footing's open neighbor until it is protected.

The record this produces

One record per footing: the step 1 load comparison; measured diameter, depth, and frost-line comparison; concrete condition findings; connection type and condition; the movement check; the decision, its driving finding, and any sign-off; and photos before backfill. The office reads it before releasing the framing crew. The design professional reads the findings themselves, not a summary, when asked to sign an augment. The next crew reads it if a footing question ever comes up again, since one verified and buried is otherwise invisible to anyone who did not dig it up themselves.

One run, including the stop that fired

Job: rebuild and footprint expansion of an attached deck, from 8 by 12 feet to 12 by 18 feet. Two existing footings from a 1994 permit file sit along the old outer beam line; the new design adds one footing and reuses the two originals under a repositioned beam.

Step 1: the old permit note gave a footing count only, no bearing value, so the comparison ran forward from the new design alone. New joists span 12 feet, giving the beam 6 feet of tributary width, and the reused interior footing now carries 9 feet of beam length (an 18-foot beam split into two 9-foot bays): 9 by 6 is 54 square feet of tributary area at 50 psf combined, 2,700 pounds, against roughly 32 square feet and 1,600 pounds it likely carried under the original tighter post spacing. The load nearly doubled, noted before anyone picked up a shovel.

Steps 2 through 4 ran clean: valid ticket, the footing exposed on three accessible sides (the fourth ran under an attached patio slab, left for a probe rod only), a measured 14-inch minimum diameter at its narrowest section.

Step 5 fired the stop. The jurisdiction's current adopted frost depth here reads deeper than the 30 inches this footing measured from today's grade. Twenty mild winters had produced no visible heave, but the stop rule does not permit reuse against a depth that fails today's minimum. Steps 6 through 8 still ran for the record and came back clean: sound concrete, an intact standoff base, no undermining.

Step 9: the decision was Augment, since only depth had failed. A design professional specified an independent pier beside the existing footing to carry the full new load, the original footing retained as a secondary bearing point per the engineer's detail, sign-off attached. Step 10 held the excavation open and covered until the pier contractor's schedule, then backfilled once the pier was set and inspected.

When the site does not match this procedure

If a footing's fourth side cannot be exposed, under an attached slab or the house foundation, record what could not be verified and treat that side as unverified, not sound; a design professional's review outweighs a Reuse call on three sides out of four. With no permit or design record at all, step 1 runs entirely forward from the new design's own load.

References

• See related: deckbuilding-existing-deck-safety-assessment, for a general condition assessment beyond the footing
• See related: deckbuilding-footing-layout-and-inspection-readiness, which owns new-footing layout and inspection criteria and receives the Reject path here
• See related: deckbuilding-concrete-footing-excavation-and-pour-technique and deckbuilding-post-base-and-post-installation-technique, for the hand technique behind a Reject repour or an added connection
• IRC Section R403.1.4.1, footing depth below frost line, and IRC Table R301.5, deck live and dead load provisions, edition your jurisdiction has adopted
• OSHA 29 CFR 1926.1153, respirable crystalline silica in construction