BAL- FZ

Extreme Risk.

  Direct exposure to flame front, as well asr adiant heat and ember attack.

The most stringent building requirements apply to this level

BAL- 19

Moderate Risk.

Ember attack risk increasing along with burning debris and radiant heat. 

Some specific design structures apply

BAL- 40

Very High Risk,

Likelihood of exposure to flames as well as increased levels of radiant heat and ember attack.

Specialised construction methods and materials required.

BAL- 12.5

Low Risk.

Low risk of ember attack, primary risk from radiant heat. Some extra measures required, such as sealing gaps

BAL- 29

High Risk.

Possible exposure to flames. Ember attack and radiant heat risk high.

More specific design structures apply

BAL- LOW

Insufficient Risk.

Not enough risk to warrant special building requirements