Horizontal safety nets, S system – border rope according to EN 1263-1
System S represents the most common form of safety netting encountered on construction sites: a large, horizontal safety net suspended beneath the working level, bounded by a heavy-duty border rope (perimeter rope) and tied directly to the building structure. Its purpose is to arrest a falling person rather than fence them off from an edge. This allows workers to move freely across the entire protected net area without harnesses or lanyards restricting their range of movement. It is a key component of temporary Collective Protection Equipment (CPE) used during the erection of commercial buildings, industrial hall roofs, and precast concrete floor slab assembly. Below, we detail exactly what System S entails under the EN 1263-1 standard, its minimum allowable dimensions, how fall height and catch width are calculated, the required clear fall space underneath, and the required strength ratings for ropes and anchorage points.
What the S system is, and what sets it apart from the other EN 1263-1 systems
EN 1263-1 standard distinguishes four safety net systems. Whether a net is classified as System S depends on one defining element: the border rope. This is a heavy-duty rope that passing through every perimeter mesh of the net, defining its external dimensions. It is the border rope that transfers the impact load from the netting to the building structure, and it is tied directly to anchorage points—never individual mesh strands. The netting mesh itself features square or diamond openings measuring under 100 mm, with mesh strands manufactured from High-Tenacity (HT) polyamide or polypropylene. The minimum energy absorption capacity of the netting is 2.3 kJ. The dynamic impact test for System S safety nets involves dropping a smooth 100 kg steel sphere twice onto the net from a height delivering 7 kJ of kinetic energy — corresponding approximately to seven meters. The three remaining netting systems address different situations and we covered on dedicated pages:
- System T – a net fixed to horizontal cantilever brackets, installed storey by storey along the façade. Read more under system T safety nets.
- System V – a net with border rope on gallows-type brackets, suspended vertically along slab edges. Read more under system V safety nets.
- System U – A vertical safety net attached to a supporting framework, used as a protective wall during roofing, scaffolding, or open edge work. This is how our edge barrier system works, as described under hall and roof edge protection.
Minimum required size: 35 m² and shorter side 5 m
System S has a mandatory minimum size requirement, which is its most significant practical limitation. A System S safety net must have a surface area of at least 35m2, with its shortest side measuring at least 5.0 meters (Clause 5.1 of EN 1263-2). Below these dimensions, the netting simply cannot deflect sufficiently to absorb dynamic fall energy. During a person fall, small nets lack adequate deflection in it, resulting in a sharp, dangerous surge in impact force transmitted to both the human body and the structural anchorage points. Nets smaller than 35 m2 are outside the scope of the EN 1263 standard—the standard does not prohibit them; it simply does not cover them. Since there are no standard requirements to evaluate them against, there is no legal basis to issue an EN 1263 Declaration of Conformity for small nets in System S. If a supplier offers you a small net claimed to be “certified under EN 1263”, it is worth to request the actual document and check what it specifically covers. In practice, this means System S is not the appropriate solution for securing small openings—such as roof skylights, elevator shafts, or individual floor voids. For skylight fall protection, dedicated systems are required, which we cover on our page for skylight protection.
Fall height and catch width
Safety netting must be installed as close below the working level as possible. Fall height is defined as the vertical distance between the protected working edge and the point of impact on the net. The standard limits fall height to two threshold values: no more than 6 m under normal conditions, and no more than 3 m within the edge zone (defined as the perimeter belt within 2 m of the net border). These requirements derive directly from the energy absorption capacity of the netting.
Catch width – the horizontal distance between the outer edge of the work area and the outer edge of the safety net—depends directly on the vertical fall height:
| Fall Height (He) | ≤ 1,0 m | ≤ 3,0 m | ≤ 6,0 m |
|---|---|---|---|
| Min. Catch Width (b) | ≥ 2,0 m | ≥ 2,5 m | ≥ 3,0 m |
Values according to EN 1263. On working surfaces inclined by more than 20° the catch width is at least 3.0 m.
A specific condition applies to sloped work surfaces exceeding a 20° pitch: the catch width must be at least 3 m, and the distance between the farthest working point and the lowest point along the net edge must not exceed 3m.
Required fall clearance under the net
Safety netting arrests a fall by deflecting. Therefore, sufficient clear space must remain underneath so that a falling worker does not strike any rigid obstacles or ground surfaces as the net deforms. Dynamic deflection depends on the shorter side length of the net and the fall height. The standard defines this through two key formulas: initial deflection should not exceed one-tenth of the shorter side length, and the total vertical distance including initial deflection must not exceed 6 m. Furthermore, if traffic routes or lower working levels exist beneath the net, an additional safety margin must be kept—ensuring clear distance remains greater than zero even at maximum dynamic deflection. This critical clearance dimension is often overlooked during site planning and frequently determines whether horizontal netting can be installed at a given location.
Net suspension: ropes, anchorage points and structural loads
System S safety nets are secured to the host structure via the border rope, using tie ropes*, carabiners, shackles, or bracket hooks. The distance between individual attachment points must not exceed 2,5 m, and each suspension point must be engineered to withstand a characteristic load of at least 6 kN. The force distribution along the net border is non-uniform: load at corner anchors is zero, rising toward the span center in a characteristic sequence—4 kN, 6 kN, 4 kN.
*with a breaking strength of 30 kN for a single-branch rope, or 15 kN for a two-branch rope
Below you will find the required strengths of the individual components in a table:
| Component | Required strength |
|---|---|
| Border rope | above 30 kN (safety factor 2) |
| Tie rope – single-branch suspension | at least 30 kN |
| Tie rope – two-branch suspension | at least 15 kN |
| Coupling rope (joining nets) | at least 7,5 kN |
| Individual attachment point | at least 6 kN |
| Spacing of attachment points | maximum 2,5 m |
| Galvanised steel cables | above 50 kN |
| Galvanised carabiners with safety nut | above 20 kN |
| Minimum energy absorption of the net | 2,3 kJ |
Values from EN 1263-1 and from the instructions for use supplied with the product.
Two separate safety nets are joined by means of a certified coupling rope (Type O, min. 7,5 kN breaking strength) woven mesh by mesh through both net panels and tied at opposite corners. Any gap created between connected net borders must not exceed 100 mm. Alternatively, net panels may overlap by a minimum width of 2 m.
When securing large floor slab openings—such as atriums, lightwells, or shafts—the border rope is threaded through cast-in or drilled rebar hooks spaced every 50 cm along the slab edge. Hooks are made of Ø8mm ribbed rebar anchored into Ø20 mm holes to a minimum depth of 15 cm and positioned at least 10 cm back from the slab edge.
Applications of System S safety nets in construction
Horizontal type S safety netting serves as core collective fall protection across key construction sector:
- Steel and Precast Concrete Hall Roofs: Securing open roof bays during trapezoidal sheeting, sandwich panel laying, skylight fitting, and flat roof insulation. Combined with perimeter edge protection system such as RAND+, they deliver complete fall protection during height works.
- Large slab openings and shafts: Securing atrium voids, elevator shafts, service openings, and mezzanines on commercial building sites.
- Bridge construction: Underslung fall arrest protection for crews performing formwork and rebar assembly below bridge decks. Specialized civil engineering setups are covered under bridge and viaduct protection.
- Fixed and movable nets systems: Across expansive industrial halls, System S nets can be fixed permanently beneath the entire roof structure or suspended from steel messenger cables with pulleys/travelling carabiners, moving progressively alongside installation works.
Fine Debris Overlay: Where work above a System S net generates falling mortar, concrete chips, or involves small hand tools, a fine debris mesh is overlaid onto the primary net.
Labelling, test mesh and mandatory annual inspection
Under EN 1263-1, every safety net must carry a permanently sewn-in factory label specifying: manufacturer name, manufacture date, net classification (system and mesh size), precise product description, minimum energy absorption capacity, mesh breaking strength, and the mark of an accredited independent inspection body authorised to inspect nets. The absence of any of these items is a critical a warning sign.
Attached to the net perimeter are loose fibre tests meshes bearing the exact same serial number as the main label. This is the only valid method to verify that a test mesh belongs to that specific net. Synthetic fibres (polypropylene and polyamide) undergo gradual strength loss due to solar UV radiation. To extend the certified operational validity of a safety net for an additional 12 months, one test mesh is cut prior to the end of the 1-year period and submitted to the manufacturer’s testing laboratory to verify tensile breaking strength. A passing test result re-certifies the safety net for another year of active service.
A safety net must be removed from service immediately if it has arrested a person fall or heavy object impact (unless re-tested), if its energy absorption capacity is no longer guaranteed, or if visible damage appear: severe abrasion, severed mesh strands, or damaged border ropes and loops. Storage conditions directly dictate whether a safety net passes its annual test. Nets must be stored in dry, well-ventilated areas, away from direct heat sources and sunlight, and completely separated from aggressive chemicals such as acids, alkalis, solvents, or oils.
FAQ – frequently asked questions about type S safety nets
What is the minimum required size for System S safety net?
A minimum surface area of at least 35 m² with a short side measuring no less than 5 meters. This is a strict requirement under Clause 5.1 of EN 1263-2, not merely a manufacturer recommendation. Nets smaller than those dimensions fall outside the scope of EN 1263—they are not forbidden, but because no standard criteria exist for them, no valid EN Declaration of Conformity can be issued for a System S net below these dimensions.
What is the required breaking strength for the border rope on a System S net?
The border rope (passing through every perimeter mesh) must have a tensile breaking strength exceeding 30 kN, incorporating a safety factor of 2. It is made of high-tenacity polyamide and tested in full compliance with EN 1263-1.
Which ropes are used to install System S nets and what are their required strengths?
The tie rope is used to attach the border rope of a type S net to the supporting structure. It has the same strength as the border rope itself — above 30 kN — when suspended on a single branch (single tie rope); on a two-branch suspension 15 kN is sufficient (double tie rope). Coupling ropes (type O) are used to join adjacent net panels to one another. They must have a strength a minimum breaking strength of 7.5 kN.
Can a System S safety net be anchored to timber structures?
The EN standard does not restrict the building material itself, but specifies the structural load each anchor point must sustain: at least 6 kN, with anchor spacing not exceeding 2.5 m. Thus, feasibility depends on the structural load capacity of the specific member rather than its material. On concrete slabs, rebar hooks are anchored into slab edges; on steel halls, tie ropes loop around structural members. On timber structures, anchorage method is evaluated individually based on engineering drawings, as timber grade and cross-section dictate load capacity. Send us your structural drawings and our team will verify anchorage points prior to quoting.
What is the maximum allowable fall height onto a System S safety net?
The maximum vertical fall distance from the working surface onto the net is 6 m. However, within a 2 m perimeter belt along the anchored net edge, the fall height must not exceed 3 m. Best safety practice dictates suspending the net as close below the working level as possible.
Do you need a type S netting for a specific project?
Are you planning industrial hall roofing, precast concrete slab installation, or floor void protection? Contact our engineering team today.
System S is just one of four safety net configurations defined under the EN 1263 standard. If you are not sure which of them best fits your building, explore our complete guide: a comparison of all safety net arrangements: S, T, U and V.