Railing and Baluster Final Inspection

Purpose

The guard is the only part of a deck whose job is to catch a person who has already lost their balance, and it is the part a crew builds last, at the end of a long week, often to a layout habit rather than to a measurement. This procedure closes the guard out with three gauges and one connection check, each carrying a number, before the inspector or the customer is standing at the edge. Nobody should find out the post connection was short by leaning on it.

Scope

Covers acceptance of guards, guard infill, stair guards, handrails and gates on new or rebuilt residential deck work, from first measurement to a signed acceptance record. It runs before the permit final inspection, not after.

It does not cover condition assessment of guards on a deck someone else built, which deckbuilding-existing-deck-safety-assessment owns, and it does not cover guard design. Where a guard is site-built without tested connector hardware, a licensed design professional owns the detail and this procedure only verifies it was built as drawn.

Roles and handoffs

Procedure

1. Establish whether a guard is required here, and to what height, before measuring anything. Under IRC R312.1.1 a guard is required where the walking surface is more than 30 in above the floor or grade below, measured within 36 in horizontally of the edge, so grade under the deck decides this and grade is not flat. Measure at the low point. Acceptance: a written note of the highest drop at each edge and the required height that follows, 36 in minimum for a deck guard under IRC R312.1.2 and 34 in minimum on the open side of stairs measured vertically from the tread nosing line. Wrong: assuming a low deck is exempt because the door end is close to grade. Stop rule: any edge where the drop is over 30 in and no guard was in the scope goes back to the office as a scope question before the deck is called done. Hazard: this measurement is taken from the ground, not by walking an unguarded edge, and any edge over 6 ft is treated as an unprotected side under 29 CFR 1926.501(b)(1) until its guard is verified.

2. Measure guard height at every post and at mid-span of every bay. Read from the walking surface to the top of the top rail, at the post and again between posts where the rail can sag, recording each figure rather than a range. Acceptance: every reading at or above the required height from step 1, none under it by any amount. Wrong: measuring at one post and calling the run good, which misses a section built before a stair tread was shimmed or a surface board was replaced with a thicker one. Stop rule: a single reading under the minimum fails the whole run, and the section is re-set rather than shimmed at the rail. Hazard: do not lean over the rail to read the far side of a corner post; move around and read it from there.

3. Run the 4 in sphere across every infill bay, including the end gaps. IRC R312.1.3 requires that guard openings not allow passage of a 4 in diameter sphere. Check the gap at each end of the bay against the post as well as between balusters, because the remainder of a layout lands there. Acceptance: the sphere will not pass anywhere, and the widest measured clear gap is recorded per bay. Wrong: laying out balusters at a habitual on-center spacing rather than computing the bay, which is how a shop ends up with 1-1/2 in balusters on 5-1/2 in centers, exactly 4.0 in clear, with nothing left as margin. Stop rule: any bay the sphere passes is re-laid completely with a recomputed baluster count; do not add one baluster to a bay and leave the rest of its spacing uneven. Hazard: the sphere check puts the inspector's hands and head near the open edge, so it is done from inside the deck.

4. Run the two stair-specific gauges, which are different numbers from the deck guard. On the open side of a flight the guard opening is checked against a 4-3/8 in sphere, and the triangle formed by riser, tread and bottom rail against a 6 in sphere, both under IRC R312.1.3 exceptions. Acceptance: neither gauge passes anywhere on the flight, recorded per flight. Wrong: applying the 4 in deck number to the stair triangle and rejecting sound work, or the 6 in triangle number to vertical infill and passing an opening that should have failed. Stop rule: a gauge that passes means the flight's infill is re-laid before the handrail goes on, since the handrail hides the fasteners you will need. Hazard: check stair guards with the flight blocked to traffic, because the person running the gauge is working sideways on the stairs.

5. Verify the post-to-frame connection against the schedule, because this is the check you cannot make by looking. IRC Table R301.5 sets the guard design load at a 200 lb concentrated load applied in any direction at any point along the top, with infill checked at 50 lb horizontally on 1 sq ft. You do not reproduce that with your hands. What you verify is that the connection matches the connector manufacturer's tested schedule: right hardware, every hole filled with the specified fastener, correct fastener length into sound framing, blocking where the schedule calls for it. Acceptance: hardware model matches spec, fastener count and type match the schedule, blocking present, no post base moving visibly under a firm two-hand push at rail height. Wrong: treating a hand push that shows no movement as evidence the connection meets 200 lb, which it is not. Stop rule: a post you cannot confirm against a schedule is not accepted; open the fascia and look, or replace the connection with hardware you can document. Hazard: nobody puts body weight against a guard as a test while standing at height on the deck side.

6. Check the handrail as a separate assembly from the guard. A handrail is required on at least one side of a flight with four or more risers under IRC R311.7.8, at 34 in to 38 in measured vertically above the tread nosing line, continuous the full length of the flight, and graspable per the Type I or Type II profiles in R311.7.8.5. Acceptance: height inside the band at top, middle and bottom; the required clearance between rail and wall; a profile a hand closes around without releasing. Wrong: a 2x4 laid flat on a guard called a handrail, which meets neither the graspability requirement nor usually the height band. Stop rule: a handrail outside the band or not continuous is corrected before the final is called, because it fails a whole flight. Hazard: shaping the graspable profile releases treated wood dust, so cut and sand outdoors with eye and respiratory protection matched to the exposure.

7. Close out hardware, gates and finish, then sign the acceptance. Confirm every fastener and connector carries the coating the preservative requires, that gate hardware self-closes and latches, and that no fastener head is proud of a surface a hand slides along. Acceptance: no bare-steel fastener anywhere in the guard, gate latching on release from a half-open position, no proud head or splinter on a handrail or top cap. Wrong: standard electro-galvanized screws used in the rail because that was the box already open, which streak and lose their heads within a season in copper-based treated lumber. Stop rule: mixed or wrong-coating hardware is replaced, not sealed over. Hazard: spring-hinged gates are under tension when held open, so release them under control rather than letting them snap.

The record this produces

One Guard Acceptance Record per deck, filed against the job number and produced before the permit final is called. Fields: date and lead; the highest drop at each edge and the guard height required from it; the height reading at every post and every mid-span, individually; the widest measured clear gap per bay and the sphere result; both stair gauge results per flight; the connector model, the schedule checked against, fastener count and type, blocking present yes or no; handrail height at three points, continuity, profile type; hardware coating; gate latch result; a photo of each rebuilt bay; the lead's signature.

Who reads it later: the inspector, if a finding is disputed; the office, if a customer reports movement a year on; and the crew that built it, when a rework pattern shows up across jobs. A record listing one height reading per run answers none of those, which is why step 2 records every reading.

Worked pass

New 42 ft of guard on a rebuilt deck, eight bays, one stair flight of six risers, one gate.

Step 1: lowest grade under the north edge puts the drop at 41 in, so a guard is required and the height minimum is 36 in on the deck and 34 in on the stair side. Recorded.

Step 2: sixteen readings taken, post and mid-span. Lowest is 36-1/8 in. Pass.

Step 3: FAILS. The crew laid out balusters at the shop's habitual 5-1/2 in on center with 1-1/2 in square balusters, which leaves 5.5 minus 1.5 = 4.0 in of clear opening, exactly at the gauge and with no margin. The sphere passed in three of the eight bays where the layout remainder landed in the end gap, the widest measured at 4-1/8 in. Stop rule taken: those three bays are re-laid completely, computed per bay rather than by habit. Bay 4 measures 46-1/2 in clear between posts. With n balusters there are n+1 gaps, so the clear gap is (46.5 minus 1.5n) divided by (n+1). At n = 7 that is 36 / 8 = 4.5 in, which fails. At n = 8 it is 34.5 / 9 = 3.833 in, which passes with real margin. Bays 4, 6 and 7 rebuilt at 8 balusters each.

Step 4: stair flight checked with both gauges. The 4-3/8 in sphere does not pass the open-side infill; the 6 in sphere does not pass the riser, tread and bottom-rail triangle. Pass.

Step 5: tested connector at every post location, model matched to spec, all holes filled with the specified fastener, blocking present in every bay checked from below. No visible movement at any base under a firm two-hand push, recorded as a screening observation and not as a load test.

Step 6: handrail reads 35-1/4 in at the top, 35-1/2 in mid, 35-3/8 in at the bottom, continuous, round profile. Pass.

Step 7: guard fasteners are the specified coating, gate self-closes and latches from a half-open position, no proud heads on the cap. Signed.

What the pass shows: every reading in steps 2, 4, 5 and 6 was comfortably inside its criterion, and the run still failed, because a habit spacing that lands exactly on a limit fails as soon as the remainder of a bay has to go somewhere. The three rebuilt bays cost part of an afternoon. Found at the permit final instead, they cost the final, a re-inspection, and a customer who now watches everything else.

When the site does not match this procedure

If the guard was built to a stamped detail rather than tested hardware, step 5 becomes a comparison against the drawing and any deviation goes back to the design professional, not to the lead's judgment. If the customer asks to keep an existing guard on a rebuilt deck, that guard runs through the existing-deck assessment first. If a gauge result is on the line, treat it as a fail: a bay rebuilt unnecessarily costs an afternoon, and a bay passed wrongly is a child-sized opening at height.

References

• IRC Section R312 Guards and Window Fall Protection, including R312.1.1 where required, R312.1.2 height, and R312.1.3 opening limitations and their stair exceptions, in the code edition your jurisdiction has adopted
• IRC Section R311.7.8 Handrails, including height and R311.7.8.5 grip size
• IRC Table R301.5 minimum uniformly distributed live loads, including the concentrated load on guards and handrails
• Connector manufacturer's tested guard post connection schedule and corrosion guidance for preservative treated lumber
• See related: deckbuilding-existing-deck-safety-assessment, deckbuilding-customer-walkthrough-and-punch-list