Building Easement and Open Space Definition

Property Development Challenges

During our terraced housing development project, our team faced a common question which is “Does the easement area of a building, marked for a proposed soakage system and directly adjoining the building, require a fire rating?” Although the initial assessment seemed straightforward, a deeper examination added layers of complexity to the query.

The NZ Building Code and FRR

The NZ Building Code highlights specific criteria about external fire spread and fire resistance rating (FRR). C/AS1 5.1.1 clarifies the conditions under which external walls should have an FRR, especially when there's no sprinkler system in place. One of the significant points during our research was determining the definition of 'open space' within the Building Code, leading us to evaluate if the proposed soak pit falls under the 'building' category.

Understanding the Definition of 'Building'

The Building Code provides an in-depth description of what can be categorized as a 'building', from temporary structures to systems linked to the primary structure. Our analysis suggests that the term “attached” indicates a direct connection to the building. Since the soak pit is placed underground without any direct attachment, it doesn't seem to fit this classification. Moreover, the soak pit doesn't align with a Network Utility Operator (NUO) system, but provision (9)(c)(ii) insinuates it might be likened to “other similar stand-alone machinery systems.”

Conclusions and Recommendations

After thorough research, we determined that the soakage system doesn't align with the standard 'building' definition. Recognizing it as an underground structure, distinct from the descriptions in the Building Act, it's apparent that the easement area can be labelled as an 'open space'. This offers clarity on guidelines concerning external fire spread risks. For complex situations like this, seeking insights from expert teams like THE DESIGNFIRE can be a wise option.