Have you ever been told on site that you "need a non-combustible material" or that "semi-non-combustible will do" and been unsure what to actually buy? Non-combustible, semi-non-combustible and flame-retardant are not simply degrees of "burns or doesn't burn". Korean building and fire codes define different test criteria and different mandatory zones for each. Choose wrongly and you risk failing handover inspection, or legal liability in a fire.
The three definitions
| Non-combustible | A material that does not burn. It does not combust even when exposed to flame or high heat. Concrete, stone, metal, Cerakwool, silica and glasswool — inorganic materials. |
| Semi-non-combustible | Close to non-combustible but short of the standard. It does not burn for a defined period and releases only limited harmful gas. |
| Flame-retardant | A material treated to resist burning. It will ignite, but it self-extinguishes and suppresses flame spread. |
KS test criteria — how is it judged?
Korean criteria are based on the Enforcement Decree of the Building Act together with KS F ISO 1182 (non-combustibility), KS F 2271 (gas toxicity) and KS F ISO 5660 (cone calorimeter).
| Non-combustible (KS F ISO 1182 + KS F 2271) | A 20-minute furnace test at about 750°C — peak furnace temperature must rise no more than 20 K above the final equilibrium temperature, mass loss must be 30% or less, and the gas toxicity test must be passed |
| Semi-non-combustible (KS F ISO 5660-1 + KS F 2271) | Total heat release of 8 MJ/m² or less over 10 minutes of cone calorimeter heating, with peak heat release rate not exceeding 200 kW/m² for 10 seconds or more continuously, plus the gas toxicity test |
| Flame-retardant (KS F ISO 5660-1 + KS F 2271) | Total heat release of 8 MJ/m² or less over 5 minutes of cone calorimeter heating, with peak heat release rate not exceeding 200 kW/m² for 10 seconds or more continuously, plus the gas toxicity test |
✅The key difference between semi-non-combustible and flame-retardant is the test duration. In the same cone calorimeter test, semi-non-combustible must hold total heat release below 8 MJ/m² for 10 minutes, flame-retardant for 5 minutes. Semi-non-combustible is therefore the higher grade, lasting twice as long.
Insulation materials by grade
| Glasswool (glass fiber) | 🟢 Non-combustible — inorganic, certified to KS L 9102 |
| Mineral wool (rock wool) | 🟢 Non-combustible — inorganic, usable in fire compartments |
| Cerakwool (ceramic fiber) | 🟢 Non-combustible — for service above 800°C |
| Silica materials | 🟢 Non-combustible — heat resistant above 1000°C |
| Aerogel (inorganic based) | 🟢 Non-combustible to 🟡 semi-non-combustible — varies by product, check the certificate |
| PIR urethane (flame-retardant treated) | 🟡 Semi-non-combustible to 🔴 flame-retardant — KS-certified products can be semi-non-combustible |
| PUR urethane (standard) | 🔴 Flame-retardant — the grade depends on whether it is treated |
| Rubber foam (NBR/EPDM) | 🔴 Flame-retardant to ❌ none — a treated product must be specified |
| EPS (expanded polystyrene) | ❌ Combustible — legally restricted in many zones |
Where non-combustible material is mandatory under the Building Act
Under the Rules on Evacuation and Fire Protection Structures of Buildings (Ministry of Land, Infrastructure and Transport), non-combustible or semi-non-combustible insulation must be used in the following zones.
- Fire compartment boundary walls, floors and ceilings — non-combustible required
- Interior finishes in basements and windowless floors — non-combustible or semi-non-combustible
- External wall insulation on apartment buildings — semi-non-combustible or better (tightened from 2022)
- Piloti ceilings and structures — non-combustible
- Retail, medical and educational facilities — semi-non-combustible or better
- Hazardous material handling areas in factories — non-combustible recommended
Choosing on an industrial site
- General industrial pipe insulation: glasswool or mineral wool, non-combustible — minimising fire risk
- Fire compartment penetrations: non-combustible material plus a certified penetration seal, without exception
- Hot plant (300°C+): mineral wool or Cerakwool, non-combustible — there is no alternative
- Cold piping (chilled and refrigeration): if using urethane, confirm a semi-non-combustible certified product
- External wall insulation: semi-non-combustible or better is mandatory — choose glasswool or mineral wool board
- Cleanrooms and semiconductor plants: non-combustible is essential, to eliminate gas release risk
Checking certificates
When buying insulation, always request a test report or KS certificate from an accredited laboratory (KCL, FITI, KOTITI and others). "I was told it's non-combustible" is not legal proof. Sebang Provision supplies KS certificates and test reports with the products we quote.
⚠️Insulation in fire compartments, external walls and escape routes must be a certified non-combustible or semi-non-combustible product. Using uncertified material can mean failing handover inspection and legal liability in the event of a fire. If you need certificates, contact us: +82 10-4266-9745
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