What is a separate building

Hi All, I have been presented with a question regarding if a building is separated or not. The building is close to another (but not touching). I have declarations from the Architect and the Structural engineers both confirming that the building is architecturally and structurally independent. A counter argument has been put forward saying that as it forms part of a range of buildings and they are connected by electricity etc, then they (the multiple buildings) should be considered as a single building. This is an old (and I thought dead argument) because even when I was at BIA/DBH/MBIE the advice was to treat a separate building as a separate firecell. That was also in consideration or “separate” simply meaning “not attached”… The “logic” was that certain building groups (hosiptals/Prisons/Marae/schools/farms/factory sites could be considered as a single building (so alarms or sprinklers in all buildings if only one building needed that particular system. Have things changed now? do we have to treat multiple buildings on a single site as a single building? Does anyone have any MBIE etc advice to help clarify this situation


Does the building fall under Section 8 (1) ©?
“includes any 2 or more buildings that, on completion of building work, are intended to be managed as one building with a common use and a common set of ownership arrangements”

Being connected electrically or even having a common main switchboard does not mean that they are being managed as one building, that’s just electrical infrastructure. If that logic was applied then all buildings attached to the electrical grid would be treated as one building. That would be absurd.

The distinction in Section 8 is if they are intended to be: managed as one building. For hospitals and prisons that’s usually the case. For other buildings/sites that is not certain.

Looking at Section 8-1-c of the Building Act where building is defined:

“includes any 2 or more buildings that, on completion of building work, are intended to be managed as one building with a common use and a common set of ownership arrangements”

The new building is new work, so complies in full. The existing building (which is part of the common use and ownership etc.) is by that definition also part of “the building”, would then be an “alteration” per S112. It needs to comply ANARP with means of escape, disability access and everything else to be no worse.

If for example, the new building is against e.g. an old age pensioners flat, then you will need to consider fire spread to the sleeping accommodation although it may well pass C/VM2 without them… If it is industrial buildings or offices, then it may depend if there is a fire alarm connecting the 2 buildings (so everyone knows there is a fire) and/or e.g the distance apart vs time to flashover. If it is far enough apart that it complies with radiation levels at or 1m past the boundary, then it will comply in full irrespective of being “one building” or not.

I would recommend that you make a decision in the context of the arrangement. If the two buildings are close to a boundary and the proposer is trying to play code lawyers and cut down on radiator size by claiming separate buildings then I would say no - we consider that it is a single building. I would look at the proximity of the buildings in a fire safety context. It would appear that section 8(1)© of the Building Act gives you that flexibility.

nothing to do with the radiation Robert. All of that is sorted out. There is no sleeping and no relevant boundaries to protect, as the new building is remote from all boundaries. The new building is facing an existing building. The new building complies to the AS (in full). The issue has been raised because the inclusion of separate buildings (as a single building) is being pushed to drag in C3.8…

If that is the case then large industrial sites (owned by a single legal entity) will be subject to C3.8 as a default. I ma not convinced that the interpretation of a separate building is being used appropriately.

Look at the intent of C3.8 and there’s your answer. If both buildings are going to be involved in a single fire event for C3.8 then I would consider them both to be a “building” under section 8(1)`Preformatted text© of the building act

I think it may be simpler than that:

Firecell is defined as "Any space including a group of contiguous spaces on the same or different levels within a building, which is enclosed by any combination of fire separations, external walls, roofs and floors.

The building (being enclosed by external walls and roof) is therefore a separate firecell, as per the definition. Therefore the Acceptable Solution deals with the building as a separate building (and separate firecell).

C3.8 states “Firecells located within 15m of a relevant boundary that are not protected by an automatic fire sprinkler system, and that contain a fire load greater than 20TJ or that have a floor area greater than 5,000m2 must be designed and constructed so that at the time that firefighters fist apply water to the fire, the maximum radiation flux at 1.5m above the floor is no greater than 4.5kW/m2 and the smoke layer is not less than 2m above the floor.”

Therefore as the new building is bounded by external walls and is not joined to the existing structures it is a separate firecell.

C3.8 deals with the firecell, not the range of buildings, and concerns itself with the independent building (being a separate firecell). C3.8 is not required to be tested as the building (as a firecell) I have been looking at as it is less than 5000m2.

Lastly it is also arguable that C3.8 is not a means of escape issue - so under s112 need not be used in any case for existing firecells (the other buildings combined).

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Assuming that the AS are in compliance with the NZBC, then NZBC C/ASX 5.2.1 states that so long as the buildings do not contain sleeping accommodation or exitways, then horizontal fire spread between buildings with a common owner on a single title does not need to be considered. I have endeavoured to apply this to a S112 project, but the BCA adamantly refused to accept it. No point in going for a determination, as the time frame will be too long.
Paul C

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