What are those 3 number standard for in FRR?

Hi Mary,

Thank you for your question.

Fire resistance rating (FRR) means the period of time that a building element is capable of resisting the action of fire when tested in accordance with ISO 834, BS 476: Parts 20 to 24 or equivalent. Fire resistance ratings are designated by three terms, to represent the make up of the element of construction, i.e. X/Y/Z, where:
• X - Stability fire resistance rating (minutes)
• Y - Integrity fire resistance rating (minutes)
• Z - Insulation fire resistance rating (minutes)
see the enclose figure one

Please let us know if you have any further questions.

Cheers,
Tania