SettingsSettings for this calculationUS
The total length of the rooftop travel path requiring fall protection.
Measure the full length of the route workers will travel across the roof, such as along a walk pad to rooftop equipment.
The maximum spacing between fall protection anchor points along the path.
Anchor spacing is set by the fall protection system manufacturer and must satisfy the applicable safety code for the fall arrest or restraint system in use.
Anchor points needed
8 anchor points
Anchor spacing and configuration must follow the specific fall protection system manufacturer's engineering and OSHA/local safety code requirements — this is a general layout estimate, not a substitute for a certified fall protection plan.
- Bays along the path
- 7
- Anchor centres along the path
- 18.57 ft
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Roof Fall Protection Anchor Spacing Calculator: 8 anchor points — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Anchor count = ceil(path length ÷ anchor spacing) + 1, the standard layout method for spacing fall protection anchor points along a rooftop travel path (commonly 6m/20ft spacing per system manufacturer guidance)
Inputs used
- Walk Path Length
- 130 ft
- Anchor Spacing (Manufacturer-Specified)
- 19.5 ft
Intermediate steps
- Bays along the path
- 7
- Anchor centres along the path
- 18.57 ft
Confidence note: Anchor spacing and configuration must follow the specific fall protection system manufacturer's engineering and OSHA/local safety code requirements — this is a general layout estimate, not a substitute for a certified fall protection plan.
What this calculation does not cover
- Counts anchor positions and says nothing about what each one is bolted to. An anchorage for fall arrest has to hold 22.2 kN (5,000 lb) per attached worker, or be designed to twice the arrest force under a qualified person, and that load has to reach the structural deck, joist or beam. An anchor fastened to steel deck flutes, to a wood nailer or through insulation is a fitting that will pull through, and it looks identical on the roof to one that will not.
- Every anchor is a hole in the roof. Each is a penetration that has to be flashed to a detail the membrane manufacturer accepts, and on a warranted roof an anchor installed to the anchor supplier's detail rather than the roofing system's can void the warranty across the whole field — which is why anchor positions belong on the roofing drawings rather than being added after the roof is on.
- Spacing along a line does not by itself give a worker a safe fall. Someone working off to the side of the anchor line swings on arrest, and the arc carries them across the roof and into whatever is in it, while near an edge the clearance below the anchor has to cover lanyard, deceleration, harness stretch and margin — which on a two-storey building is more fall distance than the building has.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-06 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations1
- Anchor count = ceil(path length ÷ anchor spacing) + 1, the standard layout method for spacing fall protection anchor points along a rooftop travel path (commonly 6m/20ft spacing per system manufacturer guidance)
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