NR-18 Construction Perimeter

NR-18: Construction Site Perimeter & Boundary Fence

Under NR-18 (Working Conditions in the Construction Industry), every construction site has to be enclosed by a perimeter fence (tapume) that stands at least 2.20 m tall. For a rectangular lot you work out the total run of fencing with P = 2 × (width + length), then tack on something like 10–15% extra to cover gates, corners and overlaps.

The fence is only part of it. The site also has to show the mandatory construction sign required by Art. 12 of Federal Law 12.378/2010 (CAU/BR), which names the responsible architect or engineer along with the ART/RRT number and the building permit. Once you go past 20 workers, a PCMAT (Programa de Condições e Meio Ambiente de Trabalho) and a construction-industry CIPA come into play too, both anchored in Law 6.514/77.

Applications

Civil engineers and site managers lean on this to budget the tapume material (OSB, metal sheeting or wood), figure out where the vehicle gates go, size the fall-protection guardrails running along the perimeter, and put together the paperwork the labour inspector will ask for before mobilisation.

FAQ

Can the fence be lower than 2.20 m? No. Item 18.30 of NR-18 spells out 2.20 m as the floor, end of story. Some municipal codes (São Paulo and Rio de Janeiro, for instance) pile on more, like solid panels facing the sidewalk.

When is PCMAT mandatory? Once the site crosses more than 20 workers. A safety engineer has to sign it, and a copy stays in the site office so the labour auditor can pull it up.

Is fall protection required at the perimeter? Yes. Any opening higher than 2 m needs guardrails, toe boards and an intermediate rail. Per NBR 16489, the edge protection has to hold a horizontal load of 1.5 kN/m.