Determinations issued
Summaries of determinations 2005/119 and 2005/133. To read determinations in full, see the register.
Determination 2005/119
Fire alarm provisions in a two-unit dwelling
The application arises from a dispute about the provisions for emergency warning of fire required for compliance with Clause F6 of the Building Code (the First Schedule to the Building Regulations 1992) in the conversion of a house to a two-unit residential dwelling and whether the required system, if any, means that a compliance schedule is required.
The building
The building is a two-storey house on a sloping site. On the ground floor are an internal garage and a one-bedroom 'granny flat' that is being converted into a self-contained household unit separated from the garage.
After the conversion, the first floor will be a self-contained three-bedroom household unit with an internal stair to the garage. Fire separation between units will be 30/30/30, and each unit will have two escape routes, neither of which is shared with the other unit. There was no dispute that after the conversion the building would comply with the Building Code in all respects other than the provisions for early warning of fire.
Submissions/reports
The owner submitted a justification for the proposed smoke alarms in terms of C/AS1 together with correspondence with the territorial authority and a fire safety report by a firm of consulting engineers that had been submitted to the territorial authority for building consent purposes.
The territorial authority did not make a submission.
Discussion
For this building, C/AS1 does not require any fire alarms, but F7/AS1 requires each unit to have one or more domestic smoke alarms, which serve only that unit.Accordingly, the proposed battery-operated smoke alarms comply with the Acceptable Solution and therefore with the Building Code.
The Acceptable Solution (Paragraph 3.3 of F7/AS1) requires that smoke alarms shall be located on each level of each household unit on escape routes. As there is only one level, only one smoke alarm is required (within 3 metres of the sleeping space doors) unless the owner decides to locate alarms in each of the sleeping spaces rather than within 3 metres of every sleeping
space door.
As the building does not include any specified systems, it does not require a compliance schedule.
Decision
The proposed smoke alarms comply with the Building Code and the building does not require a compliance schedule.
Determination 2005/133
Refusal of a code compliance certificate for a house with a corrugated steel cladding system
The application arises from the refusal by the territorial authority to issue a code compliance certificate for a partially completed 6-month-old house unless changes are made to its corrugated steel cladding system, and whether the horizontal wall cladding on the new steel-framed external wall complies with the Building Code.
The building work
The building work consists of a detached proprietary single-storey house, situated on a sloping site in a high wind zone.
The house is of a fairly simple shape on plan with some complex features and has pitched roofs at two main levels that have wall-to-roof junctions. The exterior walls are of steel-frame construction built on timber-framed floors, supported by timber piles or poles. The external walls are sheathed with a corrugated steel cladding system, 'Zincalume'. There are no eaves or verge projections.
Submissions/reports
The owner provided plans and specifications, design documentation, warranties for the butyl-rubber membranes and written documentation rebutting the territorial authority's concerns.
The territorial authority noted that the cladding was installed without a cavity and, due to changed inspection procedures, it was unable to be satisfied on reasonable grounds that the cladding was Code compliant.
The expert's report
The expert noted that the cladding is generally straight and there are no surface undulations. The sheets have been fitted with care and generally the surface is sound. The shape of the wall framing girts and the battens to the horizontal cladding will tend to shed water to the exterior and the joint between the two is such as to prevent water moving onto the girts.
However, the expert noted that many of the cladding fixings are incorrectly installed and will initiate leaking.
The expert also had concerns regarding the corrosion of the steel wall framing that could be caused by electrolytic action or moisture ingress.
Discussion
As the horizontal cladding to the east elevation has been installed according to good trade practice, the partial cavity created between the wrap and the cladding can assist the building's compliance with weathertightness and durability provisions of the Building Code. This would remove any necessity to install a ventilated drainage cavity.
The Determination is limited to the assessment of the east elevation wall of the house. However, it should be noted that the expert found evidence of water ingress in each of the face-fixed vertically clad walls.
Decision
There is no evidence of moisture entering the house through the east elevation wall with the face-fixed horizontal cladding, therefore the cladding system on this wall of the building complies with Clause E2 of the Building Code.
However, as the cladding faults on the east elevation wall of the building are likely to allow the ingress of moisture in the future, the wall does not comply with the durability requirements of Clause B2 of the Building Code.
Although outside the scope of this Determination, it was noted that the remaining walls of the house clearly do not meet the requirements of either Clause B2 or E2 at this time.