Post and Beam Framing Standard

Purpose

Between the decking and the footing there are five interfaces: joist to beam, beam to post, post to base, base to footing, and the joist to its hanger at the ledger end. A deck stands up when all five are positively connected. It stands up for a while, and then does not, when one of them is only bearing, because gravity holds a deck down until a lateral load, a hot tub, or thirty people at a graduation party asks one connection to do something other than compress.

This procedure exists so the crew builds the load path as a chain of named connectors rather than as a stack of lumber, and so the connection nobody can see after decking goes down is the one that was inspected and photographed.

Scope

Covers post, beam and joist framing on a residential deck under the IRC, from the post base on cured concrete up to the joists hung and blocked, ready for the framing inspection.

Does not cover the ledger connection or its flashing, footings, guards, stairs or the decking surface; each has its own standard. This one starts where the footing record releases and stops where the guardrail standard begins. Does not cover engineered products such as steel beams or laminated columns, which follow the manufacturer's instructions and the engineer's detail.

Roles and responsibilities

Procedure

1. Confirm the footings are released before a post is set. Read the footing record for measured depth, measured diameter, inspection approval and cure release time. Acceptance: every footing on the layout carries all four and the release time has passed. Wrong looks like a crew setting posts the afternoon of the pour. Stop rule: an unreleased or unrecorded footing does not receive a post. This is the last step where nothing is holding anyone up.

2. Reconcile beam and post spacing against the span table rows. Confirm the beam size, the number of plies, the post spacing and the joist span against the IRC deck beam and joist span tables at the species and grade actually delivered. Acceptance: the delivered lumber species, grade stamp and size match the row the design was taken from. Wrong looks like a design run on one species and a delivery of another, which changes the allowable span. Stop rule: any mismatch goes back to the designer before cutting; do not down-space posts on the tailgate to make a substitution work. Hazard: none, but the whole rest of the procedure inherits this row.

3. Set and verify the post bases. Confirm each base is the type the design calls for, is anchored to the footing as its instructions require, and holds the post end grain up off the concrete rather than sitting in it. Acceptance: base plumb, at layout, fully anchored with every hole filled, and a visible standoff gap under the post end. Wrong looks like a post set flat on a footing where water pools, which rots the end grain from the bottom up whatever the treatment. Stop rule: a base out of layout is chipped out and re-anchored per the anchor manufacturer's instructions, not shimmed sideways. Hazard: drilling concrete for a post-installed anchor releases respirable crystalline silica, so use a dust-collecting bit or wet method under the shop's silica control plan per 29 CFR 1926.1153.

4. Cut posts to height and treat every field cut. Measure each post individually from the finished base to the beam bearing line rather than cutting a batch to one length, and flood every field cut, notch and bore with a field-applied wood preservative before it is installed. Acceptance: each post cut square within 1/8 inch across the face, height correct at its own base, and every cut end wetted to refusal with preservative. Wrong looks like a batch of posts cut to the tallest measurement and shimmed at the base. Stop rule: an untreated field cut on a ground-contact or wet-service post gets treated before assembly; once the beam is on it, nobody ever goes back. Hazard: cutting preservative-treated lumber releases wood dust that is a respiratory irritant and, for some treatments, a metal-bearing dust, so cut outdoors, upwind, with eye protection and at minimum an N95, and never burn the offcuts.

5. Build the beam with splices over posts. Lay out ply lengths so that every splice in every ply lands over a post, stagger splices between plies, and fasten the plies to the schedule the design gives. Acceptance: no splice falls between posts, splices in adjacent plies are separated by at least one bay, and the ply fastening pattern is complete end to end. Wrong looks like a ply spliced wherever the delivered lumber ran out, which puts a hinge in the middle of a span. Stop rule: a splice landing off a post is re-cut, or a post is added at the splice with the designer's approval; it is never plated over. Hazard: a built-up beam is heavy and awkward, so plan the lift with enough people or mechanical help before the last fastener goes in, and never assemble it overhead.

6. Set the beam on the posts and connect it positively. Place the beam either on top of the posts with a post cap connector, or into a notch cut per the code's notched post detail, and fasten to the connector manufacturer's full nail or screw schedule. Acceptance: full bearing across the post top or the notch shoulder, every connector hole filled with the specified fastener, and no gap between beam and bearing surface you can see daylight through. Wrong looks like a connector with half its holes empty because a nail gun could not reach, or toe-nails standing in for a cap. Stop rule: unfilled connector holes stop the step; hand-drive the remainder with the specified fastener or change to a connector that fits. Hazard: this step puts hands under a suspended beam, so the beam is supported on both posts and braced before anyone releases the lift.

7. Plumb, brace and hold it. Plumb each post in two directions and install temporary bracing that stays until permanent bracing, blocking and decking are in. Acceptance: each post plumb on a 4 foot level in two planes 90 degrees apart, every post braced in two directions. Wrong looks like a beam line braced only along its length, which racks sideways the first time someone leans a ladder on it. Stop rule: nobody climbs on or loads a frame braced in one direction only. Hazard: an unbraced post and beam assembly topples under a worker's weight, so the brace goes on before the ladder does.

8. Hang and set the joists. Seat joists on the beam with the code's minimum bearing, which for wood-to-wood bearing is 1 1/2 inches, and hang the ledger end in approved joist hangers filled with the fastener the hanger manufacturer specifies. Acceptance: bearing measured at 1 1/2 inches or more, every hanger hole filled with the specified nail or screw, and the joist tight to the top of the hanger seat. Wrong looks like roofing nails or deck screws in a hanger, or a joist hanging with a gap above the seat so the fasteners carry the load in bending. Stop rule: a hanger fastened with anything other than its specified fastener is stripped and redone; substituting fasteners voids the hanger's rated capacity and the inspector will call it. Hazard: joist ends are set from a ladder or from the frame, and once the frame is more than 6 feet above the ground the residential construction fall protection rules apply, so the crew works from a guarded surface or under a fall protection plan.

9. Block, rim and square the frame. Install the rim joist and any required blocking or bridging, then check square by comparing diagonals before anything is decked. Acceptance: diagonals agree within 1/4 inch, blocking fastened at both ends, rim fastened to every joist end. Wrong looks like blocking cut short and toe-nailed at one end only, which does nothing for load sharing. Stop rule: a frame out of square by more than 1/4 inch is pulled square and re-fastened before decking, since the boards telegraph it. Hazard: nail guns firing into end grain at the rim skate off, so use a sequential-trip trigger and keep the off hand clear of the fire path.

10. Call the framing inspection and record the frame. Request the framing inspection with the frame open, and photograph every connector type before anything covers it. Acceptance: an approved inspection on record, and a photo set showing each post base, each post cap or notch, a filled hanger, and the beam splice locations. Wrong looks like a decked frame and an inspector asking to see the beam connection. Stop rule: no decking over an uninspected frame, whatever the weather forecast says.

The record this produces

• The span table rows used in step 2: species, grade, beam size and plies, post spacing, joist size and span.
• Post schedule: base type and anchor, post size and cut height, and confirmation that every field cut was preservative treated.
• Beam build: ply lengths, splice locations by station, and the ply fastening pattern.
• Connector list: post cap or notch detail, hanger model, and the fastener actually used, by model number.
• Diagonal measurements from step 9, the framing inspection approval, and photos of each connector type before decking.

The inspector reads the connector list and the photos. The office reads the fastener model when a connector manufacturer asks during a warranty claim, and "we used the specified fastener" is not an answer, the model number is. The next crew to touch this deck reads the splice stations, because a splice they cannot see is the one they cut through adding a bump-out.

One run, including the stop that fired

Job: 20 foot by 12 foot attached deck. Joists span 12 feet clear from ledger to beam. Design beam is two 2x10 plies with posts at 0, 6 feet 8 inches, 13 feet 4 inches and 20 feet, giving three equal bays of 6 feet 8 inches.

Step 2 checked the delivery: the grade stamp matched the species and grade the beam table row was run on, so the layout stood. Step 5 laid out ply lengths to put both splices over posts, one ply as 13 feet 4 inches plus 6 feet 8 inches and the other as 6 feet 8 inches plus 13 feet 4 inches, so the two splices sit over the posts at 13 feet 4 inches and 6 feet 8 inches, one bay apart.

The stop fired here. The crew took the 16 foot stock as delivered and ran the first ply as 16 feet plus 4 feet, putting that splice at station 16 feet, 2 feet 8 inches past the post at 13 feet 4 inches and squarely in a span. The lead caught it before the plies were fastened together, and under the step 5 stop rule the splice was re-cut back to 13 feet 4 inches for one 4 foot offcut and about forty minutes. Plating over the splice is not in this procedure and is not a choice a carpenter makes on site.

Step 6 set the beam on post caps, and two of the four had one hole each left empty where the nailer could not swing, so both were hand driven with the specified nail before the lift crew stood down. Step 8 measured joist bearing at 1 1/2 inches at the beam and found two ledger-end hangers with a visible gap above the seat; both joists were dropped, re-seated tight and re-nailed. Step 9 measured diagonals 1/8 inch apart. The framing inspection cleared the next morning.

References

• IRC Section R507.4 and Section R507.5, deck posts and deck beams, including the beam span table and the post height table, in the edition your jurisdiction has adopted
• IRC Section R507.6, deck joists and joist spans, including minimum bearing
• IRC Section R317.1 and R317.3.1, preservative-treated wood in wet service and the corrosion-resistant fastener and connector requirement that goes with it
• AWPA Standard M4, field treatment of cuts and bores in preservative-treated wood, which governs step 4
• OSHA 29 CFR 1926.1153, respirable crystalline silica, and 29 CFR 1926.501(b)(13), residential construction fall protection at 6 feet
• See related: the ledger attachment and flashing standard, the footing layout and inspection readiness SOP, and the guardrail and stair code verification SOP