What is a pictogram?

A pictogram is a simplified graphic symbol that conveys a message without words. In construction you meet them everywhere: on site as safety signs, in buildings as escape route and fire safety signage, on packaging of building chemicals as hazard symbols, and on drawings as symbols for services components.

Standardised shapes and colours

Safety signs are set out in EN ISO 7010, which builds on the design rules of ISO 3864. Shape and colour carry the meaning before you even read the image:

• Red circle with a diagonal bar — prohibition (no smoking, no entry).
• Blue circle — mandatory action (wear a helmet, eye protection required).
• Yellow triangle with a black border — warning (trip hazard, high voltage, falling objects).
• Green square or rectangle — safe condition and escape route (emergency exit, first aid, assembly point).
• Red square — fire-fighting equipment (extinguisher, hose reel, call point).

Hazardous substances use a separate system: the CLP hazard pictograms, a red-bordered diamond on white. These appear on paint, sealant, cleaners, cement and resin.

Use on site

• At the entrance, a board showing the personal protective equipment required: helmet, safety footwear, hi-vis and where needed eye and hearing protection.
• At specific hazards, a warning at the spot itself: floor openings, crane operating zone, cutting equipment, asbestos work.
• Escape route and assembly point clearly marked, even though the site layout changes weekly — that is precisely when things go wrong.
• Fire-fighting equipment always marked with a pictogram, at eye level and visible from the walking route.

Practical tips

• Pick the right size. For escape route signage, EN 1838 gives a workable rule of thumb: the viewing distance is around one hundred times the sign height for externally illuminated signs and two hundred times for internally illuminated ones. A sign 20 cm high therefore works up to roughly 20 metres.
• Use standardised symbols only. Home-made images are not recognised and carry no legal status.
• Do not overdo it. Nobody reads a wall covered in signs; only post what genuinely applies at that spot.
• Maintain them. Dirty, faded or half-detached pictograms stop working; photoluminescent versions also need enough light to charge.

Related terms

• Site set-up
• Safety plan
• Personal protective equipment
• Escape route
• Fire detector

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