Safety in practice
EN 1177 and impact attenuating surfacing: fall height, depth and the impact area
EN 1177 is the test; EN 1176-1 sets the requirement. Where surfacing is needed, how deep loose fill has to be, how far the impact area reaches.
Short answer
EN 1177 is the test method that gives a surface its critical fall height; the requirement to have impact attenuating surfacing is in EN 1176-1. It applies where the free height of fall is above 600 mm and, whatever the height, under equipment that forces movement, such as a swing. Loose fill needs 200 mm up to a 2 m fall and 300 mm up to 3 m, plus 100 mm for displacement. The impact area reaches two thirds of the fall height plus 0.5 m, and never less than 1.5 m.
After EN 1176 itself, EN 1177 is the number that comes up next in this market's searches, and it is the one most often misread. It is not the playground equipment standard, and it does not say how deep the sand should be. It is a test. This guide sorts out which standard says what, and then gives the numbers an owner actually needs: the height at which surfacing becomes necessary, the depths for loose fill, the size of the impact area, and what the two figures on a supplier's datasheet mean.
EN 1177 is a test, EN 1176-1 sets the requirement
EN 1177 describes how impact attenuating surfacing is tested: a headform is dropped on it from increasing heights and its deceleration is measured. The result is the surface's critical fall height, the greatest height from which the test stays within the limits. EN 1176-1 is where the requirement lives: it says where surfacing is needed, what the largest free height of fall is, and, for loose fill, how deep the material has to be for a given fall height. When a supplier quotes a depth «from EN 1177», the number may be right but the reference is not, and that is worth knowing when you compare two offers.
Two numbers from the drop test: HIC 1000 and 200 g
The test measures two things at once. The peak deceleration of the headform has to stay at or below 200 g, and the Head Injury Criterion, HIC, a value computed from the whole deceleration curve, has to stay at or below 1000. A surface passes at a given height only if both hold, and the critical fall height is the greatest height at which they do. For manufactured surfaces, rubber tiles, poured rubber, artificial turf over a pad, that height is what the datasheet states, and it is the number to keep with the site's records.
For you as the owner that turns into one rule: the critical fall height of the surface has to be at least as high as the free height of fall of the equipment above it. Tiles rated to 1.5 m under a climbing frame with a 2.2 m fall are too weak, however neat they look.
Where surfacing is needed: 600 mm, and forced movement
The rule in EN 1176-1 has two parts, and the second is the one that gets forgotten. Impact attenuating surfacing is needed across the whole impact area wherever the free height of fall is above 600 mm, and also under any equipment that forces movement on the child, a swing, a cableway, a carousel, whatever the height. A toddler swing with a seat 400 mm off the ground still needs it, because the child leaves the seat moving. The other limit is absolute: the largest free height of fall the standard allows is 3000 mm.
Free height of fall and the impact area
The free height of fall is the greatest vertical distance from where the child's weight rests on the equipment down to the surface below: the platform they stand on, the seat they sit on, and for equipment they hang from, the hand support less one metre. The impact area is the ground that has to be covered around it, and the rule of thumb for how far it reaches is two thirds of the free height of fall plus 0.5 m, never less than 1.5 m.
For equipment with forced movement the areas are larger and shaped differently, because the child leaves the equipment while moving. A swing needs clear ground in front of and behind it along the direction of swing; a nest swing rotates as well, so the clear ground goes all the way round. Where two pieces of equipment have overlapping impact areas, it is the outer edges that count.
Loose fill: how deep, and the 100 mm that disappears
The extra 100 millimetres are not a safety margin; they are a precondition. Loose material is displaced in use: sand is kicked out from under the swing, chips are pushed away at the foot of the slide. Lay only the nominal depth and the surface is already too thin in its first season. The material matters too. Sand should be washed and free of fines, because ordinary fill sand compacts and stops absorbing anything; wood chips and bark need the particle sizes EN 1176-1 lists for them, which the supplier should be able to document, and they are replaced once they have broken down into compost.
The words in your language
CEN publishes the standard in English, French and German, but most people who look after a playground learned the subject in their own language. These are the three terms that come up first, in five of the market's languages.
| Language | Impact attenuating surfacing | Free height of fall | Critical fall height |
|---|---|---|---|
| Dutch | Valondergrond | Vrije valhoogte | Kritische valhoogte |
| French | Sol amortissant | Hauteur de chute libre | Hauteur de chute critique |
| Italian | Pavimentazione antitrauma | Altezza di caduta libera | Altezza di caduta critica |
| Polish | Nawierzchnia amortyzująca | Wysokość swobodnego upadku (WSU) | Krytyczna wysokość upadku |
| Spanish | Superficie amortiguadora de impactos | Altura de caída libre | Altura de caída crítica |
Faults you can find on your own round
When the Czech Trade Inspection Authority inspected 170 playground facilities in 2017 and found shortcomings at 28, poor impact-absorbing material was at the top of its list. Surfacing is the part of a playground that decays fastest and is noticed least, because it goes a little at a time. These are the faults an operational inspection catches.
- The hollow under the swing. Where children brake, the surface goes first. Measure there, not at the edge.
- Chips pushed away at the foot of the slide. The same fault, a different place, just as common.
- Compacted material. Bark trodden flat or frozen solid absorbs impact about as well as asphalt.
- Exposed foundations. When the fill is carried away, the concrete appears, often with an edge.
- An edging now higher than the surface. The kerb meant to hold the fill in has become a hard object to land on.
- Water and ice. No drainage means standing water in autumn and ice in winter.
- Bark that smells of soil. Then it is soil, and soil is not impact attenuating surfacing.
Measure, do not look
Push a stick or a folding rule in at several points in the impact area and measure to firm ground, not to the fluffy top layer. Write the number down. Then you have two things at once: a surface you know absorbs impact, and a series of numbers that shows how fast the material is going and therefore when the next top-up falls due. Put the measurement in as a fixed point on the operational inspection; see the checklist.
Questions and answers
What is EN 1177?
The European test method for impact attenuating surfacing. A headform is dropped on the surface and its deceleration is measured; the surface passes at a height if the peak deceleration stays at or below 200 g and the HIC value at or below 1000, and the greatest such height is its critical fall height. It is not the equipment standard and gives no depths: those are in EN 1176-1.
How deep should playground surfacing be?
For loose fill such as sand, wood chips, bark and gravel, EN 1176-1 gives 200 mm for fall heights up to 2 m and 300 mm up to 3 m, plus 100 mm because loose material is displaced in use: 300 mm and 400 mm as laid. Measure to firm ground where children land.
What is critical fall height?
The greatest fall height a surface has been tested for under EN 1177 with both limits held: peak deceleration at or below 200 g and HIC at or below 1000. The critical fall height of your surface has to be at least as high as the free height of fall of the equipment standing on it.
Does grass count as impact attenuating surfacing?
Up to a point, and the point is about a metre. EN 1176-1 lists well-kept grass and topsoil as usable for a free height of fall up to 1000 mm without testing. Above that a surface with a documented critical fall height is needed. Grass also loses what it has when it dries out, compacts or is worn to bare soil under a well-used piece of equipment.
Does the extra 100 mm apply to rubber tiles as well?
No. The allowance is for loose materials, which are displaced in use. A tile stays where it is laid and is documented instead by its critical fall height, which has to be at least as high as the free height of fall of the equipment above it.
Sources
- EN 1176 and EN 1177 – CEN/TC 136 Sports, playground and other recreational facilities and equipment (CEN-CENELEC)
- CEN-CENELEC: European Standards, and how members adopt them nationally
- ČOI: Kontroly dětských hřišť a jejich zařízení (Česká obchodní inspekce)
This article is written by August and gives a practical account of the requirements. It does not reproduce the standards EN 1176 and EN 1177, and it does not replace the annual main inspection by a competent person. If you are unsure what applies to your playground, ask a competent person or the relevant authority in your own country.
Less fuss. Lekko remembers.
Ready-made checklists built from EN 1176 and EN 1177, a reminder before every inspection, and a report you can hand over in one click.