1. OS2
  2. OP2
  3. OH1
  4. OH4
  5. OS3
  6. OS1


OS1 Fire Safety


[F20,F21-OS1.2]Applies to assemblies required to provide fire resistance.


Intent 1:

To limit the probability of:

  • an excessively high cement/aggregate ratio, which could lead to poor workability, excessive compressive strength and attendant high shrinkage, which could lead to tensile stresses and the cracking of mortar or masonry units, or
  • an excessively low cement/aggregate ratio, which could lead to weak, porous mortar and inadequate bonding with masonry units.

Where masonry construction is required to provide fire resistance, this is to limit the probability of excessive deformation or cracking, which could lead to compromised fire resistance of the assembly, which could lead to harm to persons.

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