Understanding 'defendable space'

Defendable space is a term used in planning to describe a perimeter around a dwelling which contains vegetation 'managed' to a specific standard.

‘Managed vegetation’ is vegetation which is modified and managed on-going to ensure it mitigates the bushfire as it approaches the dwelling.

The larger the area of defendable space, the lower the construction standard required, with relation to bushfire resistance.

The classification of the closest hazard (unmanaged vegetation) will influence the required amount of defendable space, ie. Forest, as a high classification will require greater defendable space than shrubland.

The slope of the land also plays a role as fire travels quicker uphill than downhill.

Managed vegetation

Vegetation within the defendable space must be managed in accordance with the following requirements:

1. Grass must be short cropped and maintained during the declared fire danger period.

   
   

2. All leaves and vegetation debris must be removed at regular intervals during the declared fire danger period.

   
   

3. Within 10 metres of a building, flammable objects must not be located close to the vulnerable parts of the building.

   
   

4. Plants greater than 10 centimetres in height must not be placed within 3 metres of a window or glass feature of the building.

5. Shrubs must not be located under the canopy of trees.

6. Individual and clumps of shrubs must not exceed 5 square metres in area and must be separated by at least 5 metres.

7. Trees must not overhang or touch any elements of the building.

   
   

8. The canopy of trees must be separated by at least 5 metres. (or 2m if stipulated in a Schedule to the BMO)

   
   

9. There must be a clearance of at least 2 metres between the lowest tree branches and ground level.

These requirements are on-going and become a planning permit obligation under the Victorian planning scheme.

Do you need greater clarity on this? Please contact us at Morrahan Services, we'd be delighted to assist.