9.21.3.10.(1)

Objective

OS2 Structural Safety

Attribution

Intent

Intent 1:

To limit the probability that:

  • heat from a flue pipe will be conducted into unprotected chimney masonry, which could lead to damage to the masonry in the vicinity of the flue pipe connection,
  • rainwater will flow across the chimney cap and into the flue, which could lead to damage to the liner due to freeze-thaw stresses, which could lead to the ingress of condensed water vapour into the cavity between the chimney liner and the surrounding masonry, which could lead to damage to the masonry due to freeze-thaw stresses, or
  • mechanical or freeze-thaw damage to the extended portion of the liner will lead to blockage of the flue or subsequent freeze-thaw damage to the upper courses of surrounding masonry.

This is to limit the probability of the collapse of the chimney, which could lead to harm to persons.

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