Scaffold Plank & Frame Takeoff
Planks and frames for a work platform by length and height, with the guardrail and toeboard lengths, the plank weight to haul, and the frame spacing the planks need.
A 36 in platform needs frames at 3 ft spacing, not 5: planks overhang 1 to 3 in and are restrained. Two planks on 5 ft frames is the 24 in platform everyone rents.
How the math works
- Planks: runs = length ÷ plank length, and the platform width decides planks per run: 24 in takes 2, 36 in takes 3, 48 in takes 4. Planks must be fully planked with no gaps over 1 in and an overhang of 1 to 3 in, restrained against displacement.
- Frames: bay spacing is 5 ft for a 2-plank platform, 3 ft for 3 and 4 planks; bays = length ÷ spacing + 1, two frames per bay, one lift per 5 ft of height.
- Guardrails: top rail at 38 to 45 in on a scaffold (42 in nominal) on all open sides, a midrail between top rail and platform, and guardrail on both sides of a run over 6 ft wide. Planks over 6 ft wide need a rail on the outboard side.
- Toeboards: 4 in minimum on all open sides and at the ends, and screens or panelling where people or equipment pass below.
- Base & ties: base jacks on every frame with a mud sill under each, plumb and pinned, ties at 4 ft o.c. of platform area (a 20 ft vertical spacing on the first lift, then every 20 ft up and 18 ft horizontally), and a ladder inside the frame width for access, never a cross-brace climb.
How many scaffold planks for a 40 foot run?
A 24 in platform with 7 ft planks: 40 ft ÷ 7 ft is 6 runs, 2 planks per run, so 12 planks. A 36 in platform takes 18 planks of 7 ft, and 12 ft planks cut the two plank run to 8 planks in 4 runs.
How high can a frame scaffold go?
Frame scaffolds stand to 125 ft without a design; above that a registered professional engineer signs it. Ties, plumb, base plates on mud sills, and a guardrail on every lift are what keep a 4 lift scaffold legal at 20 ft.
How many frames for a 40 foot, 20 foot scaffold?
On 5 ft spacing a 40 ft run is 9 bays, 18 frames per lift, and 4 lifts is 72 frames, plus 9 base jacks and 9 mud sills. Rent per bay per lift, not per frame, in most markets.