The Nail Schedule Most Framers Never Read

Table 9.23.3.4. is the quietest page in the Ontario Building Code and the one that lands in more inspection reports than any span table. A framed wall transfers a roof load through nails, not through lumber — so when a connection is undersized, the whole load path is undersized. Here is what is actually behind the numbers, from a carpenter who has had the tape pulled on every one of these joints.

Pennyweight, metric, and what "3-1/4″" really means

The numbers on the side of a nail box go back to pre-industrial England — one hundred 10d nails cost ten pennies, one hundred 16d nails cost sixteen pence, and that is literally where the "d" comes from (Roman denarius). It survived because it is short. Modern Canadian suppliers sell nails by length in millimetres, but the pennyweight label has not died. Memorize four of them: 8d = 63 mm (2-1/2″), 10d = 76 mm (3″), 10d long = 82 mm (3-1/4″), 16d = 89 mm (3-1/2″). The OBC writes every row in Table 9.23.3.4. in pure millimetres — 51, 57, 63, 76, 82, 101 — so when the code says "82 mm" and the yard ticket says "3-1/4″ spiral," they are the same nail. Then there is the type: common nails have a full smooth shank and a fat head — cheap, and they pull out under withdrawal load. Spiral (Ardox) nails twist as they drive and hold about 40 percent better, which is why every coil nail you buy in Canada is a spiral. Sinkers are coated commons with a checkered head for hand-driving. Box nails are thinner than commons, which is why OBC 9.23.3.1.(2) cross-references Table 9.23.3.1. for minimum diameter — an 82 mm box nail does not meet the code, but an 82 mm common or spiral does.

Why fastener schedules exist — the load path no one sees

Imagine 1.1 kPa of snow sitting on a 24-foot roof above a bedroom. That load travels down every rafter into every top plate. From the top plate it crosses into the studs. From the studs it drops into the sole plate, through the rim joist, into the floor joists, and finally into the foundation. The lumber does almost no work — everything is pin-connected wood, and the only thing transferring load across each joint is the nails. The whole load path is a chain of withdrawal-and-shear demands, and every chain is as strong as its weakest link. Strip one connection and the whole path fails. That is why rafter-to-plate gets three 82 mm toe nails under Table 9.23.3.4., not two — this joint sees uplift from wind as well as gravity from snow, and the code gives it an extra nail to account for the uplift withdrawal demand. Short-change a single connection and you have built a beautiful house that cannot handle the load case the engineer assumed.

Toe-nail, end-nail, face-nail — when each is allowed

The OBC never says "drive it however you want." Each row in the table specifies the technique. A toe nail enters the face of one member at roughly 30 degrees and exits into the face of the second. It is the weakest of the three in pure withdrawal — the nail only has a diagonal bite into the main member — and the code compensates by requiring more nails (three for a rafter-to-plate, four for a stud-to-plate toe connection). Drive toe nails on opposite faces alternately to keep the joint from rolling, and start the nail with a light tap before you swing full power, or the head will skate off the face. An end nail goes through one member into the endgrain of another — for example, through a plate into the top of a stud. Withdrawal capacity in endgrain is officially zero in the code-of-practice literature, so end nails count only for shear, and that is why stud-to-plate end-nailing is permitted with only two 82 mm nails when the plate is still accessible from above before the next level goes up. A face nail goes perpendicular through the face of one member into the face of another — the strongest of the three, which is why 150 mm and 300 mm o.c. spacings live on this row. Mix up the techniques and you will build a house that passes inspection on Monday and creaks in a January wind on Tuesday.

Corrosion and treated lumber — OBC 9.23.2.4.

The moment the fastener touches ACQ-, CA-B-, or MCA-treated lumber — every green deck joist, every sole plate bearing on concrete, every ground-contact sill — the corrosion clock starts. OBC 9.23.2.4. requires hot-dipped galvanized to ASTM A153 (class D or better) or stainless steel. Bright-steel and electroplated-zinc nails fail in two to five years in modern copper-based treatment chemistry. I have pulled three-year-old deck ledgers where the bright nails were black dust and the wood was held on by friction. Aluminum is not a substitute — the copper attacks aluminum even faster than it attacks bare steel. The one modern exception: zinc-borate (SBX) treated interior lumber is approved for uncoated carbon-steel fasteners per 9.23.2.4.(3). For everything else exposed to moisture or PT wood, buy the HDG nails. The box costs three dollars more and the deck lasts three decades longer.

Pneumatic nails — clipped head, full round, and screw equivalents

The clipped-head versus full-round-head fight is the oldest argument on a framing crew. Clipped heads let coil nailers stack 30 percent tighter but give up bearing area and withdrawal resistance. OBC 9.23.3.1.(1) requires nails to conform to ASTM F1667 or CSA B111 — both cover full-round and D-head nails for structural framing. Most Ontario inspectors pass a clipped-head gun on general framing and fail it on sheathing schedules where withdrawal controls — match the nail type to the table row and stay out of a rework. Ardox spiral is universally accepted and is the standard coil a Canadian framer runs. Screw equivalents trade in increasingly: a #10 × 82 mm structural wood screw substitutes for an 82 mm common under 9.23.3.1.(3) provided it is listed to ASME B18.6.1. GRK RSS or Simpson SDWS with ESR reports are accepted 1:1 for sheathing. Never substitute a drywall screw — brittle Phillips heads shear long before shear capacity.

Structural connectors — when the table is not enough

Prescriptive nailing covers the ordinary case. When it does not — coastal Great Lakes wind, Shield-country snow loads, a retrofit where you cannot swing a hammer inside an existing wall — listed connectors do the work. The short list every Ontario framer should know: Simpson H1 and H2.5A hurricane ties at rafter-to-plate, LSU / LUS28 joist hangers at beam-to-joist, HTT hold-downs at braced-wall ends for shear or seismic work. OBC 9.4.1. permits any connector whose published capacity meets the code-prescribed load path — the connector replaces Table 9.23.3.4. for that joint. A five-dollar H2.5 and eight Simpson nails beat pulling a soffit apart to toe-nail three 82s. Read the connector fastener spec like a nail-schedule row: every hole, every nail, at the stated diameter. Leave one out and the connector is decoration, not structure.