The two 2×4×14 temporary diagonals · Oct 2, 2026 · source: Ridge_Bracing.md
JCS reference: p.28, Step 7: once the rafters are plumb, “nail temporary bracing from the top of the ridge at a 45 degree angle to a block on the floor. The temporary bracing cannot stick up above the rafters.” They hold the rafters plumb (stop the frame racking north–south) until the deck is on. We use screws instead of nails.
Side view along the ridge from the east side, looking west (south on the left), to scale. The south brace (solid) is screwed to the ridge's east face; the north brace (dashed) to its west face, so they cross without touching. Both pass well below the collar ties and the RR-R connectors.
Layout
Brace
Ridge face
Top end
Foot
South brace
East face
Plumb cut at station 8″ (between R1 and R2); top corner ~1/2″ below the ridge top
On the floor at about 114–119″ from the south end
North brace
West face
Plumb cut about 8″ in from the north end (station ~136″)
On the floor at about 25–30″ from the south end
45°: about 111″ of drop from the top corner to the floor, and the same run. Each brace is about 157″ along its long edge, so cut about 11″ off a 14′ board: plumb cut at the top, level cut at the foot. Easiest: tack the top, then mark the foot against the floor.
Clearances: at R2 the brace's top edge is already ~16″ below the collar ties. The brace tops start 8″ in, clear of the ridge props.
Fastening
Top: 3 × 2-1/2″ screws through the brace into the ridge only, in the small triangle where the brace overlaps the ridge face (stations ~8–14″), at least 1″ from the brace end. Not 3″ screws: brace plus ridge is only 3″ thick.
Foot: an anchor block (2×4 scrap, 12–16″) flat on the floor right at the foot, on the side away from the brace top, screwed through the floor plywood into a joist (joists are every 16″). Then screw the brace foot to the block with 2–3 screws.
Screws: the #9 × 2-1/2″ exterior screws on hand, or any 2-1/2″ construction screw. No hand-driven nails needed.
Sequence
Ridge on the props, end rafters on, ridge level and straight.
Plumb the end rafter pairs (sight them, or a level on the gable end).
Tack each brace at the top, re-check plumb, fix the foot block and screw the foot.
Fill in the remaining pairs, re-check plumb, then fasten fully.
Leave them until the deck is nailed off. The deck takes over; then unscrew them and fill the floor screw holes along with the other brace-foot holes (Floor Prep).