Determinations issued
To date, 20 Determinations have been issued this year, all on weathertightness matters. The following are summaries of two Determinations issue recently. To read Determinations in full, see the register.
Determination 2004/81
House 64, Issued 22 December 2004
In this case the owner disputed the TA’s decision not to issue a building consent and applied for a determination. The application was referred to the Chief Executive of the Department of Building and Housing to determine whether monolithic cladding without a cavity on the proposed house would comply with the external moisture requirements (E2) and durability requirements (B2) of the Building Code.
House Design
The proposed building is a single-storey house in a medium wind zone with a relatively complex shape. The exterior will be fibre-cement weatherboard and monolithic cladding, with no junctions between the 2 types of cladding. This house is a low-risk building.
Submissions/Reports
Submissions were received from the TA and the owner. Extensive information on the polystyrene-backed cladding was provided by the manufacturer who consequently later became the owner’s agent. The information received showed that the proposed house has:
- eaves overhangs of at least 600 mm to most of the walls so that significant areas of wall have some effective shielding from rain
- external timber decks attached to the external framing, but not built over habitable space
- three valley gutters
- several wall/roof intersections
- some face-fixed fibre-cement weatherboard cladding with no drainage cavity
- some face-fixed polystyrene sheet cladding incorporating drainage grooves on the rear face of the sheets
- external walls that are constructed from timber treated to the equivalent of H1.2, which provides some initial protection from decay should it absorb and retain moisture
- been designed and documented in detail which assists in assessing the building for consent purposes and provides some assurance that it can be built to comply with the Building Code.
Decision
The Chief Executive found that the house was carefully designed and, if built in accordance with the documents submitted with the application for building consent, will comply with the requirements of clauses B2 and E2 of the building code as an alternative solution. The territorial authority’s decision to refuse to issue a building consent was reversed.
Determination 2005/14
House 12, Issued 11 February 2005
The owner of the property disputed the TA’s decision not to issue a code compliance certificate and applied for a determination. The application was referred to the Chief Executive of the Department of Building and Housing to determine whether monolithic cladding on the house would comply with the external moisture requirements (E2) and durability requirements (B2) of the Building Code.
House Design
The building is a 4-year-old two-storey house in a high wind zone. The house is a fairly complex shape with roofs at two main levels having hip and valley junctions. A large balcony has been constructed over living areas in addition to two other upper level balconies. Apart from the bay window projection where the fascia is fixed directly to the cladding, the house has 600 mm wide eaves. All external walls are monolithic clad. The house is a low- to medium-risk building.
Submissions/Reports
Submissions were received from the TA and the owner. An independent expert was commissioned to report on the cladding. The expert did not find any elevated moisture readings at the property, however defects were evident in some areas of the house which, if not remedied, will eventually allow the ingress of moisture behind the cladding. These were the:
- lack of vertical or horizontal control joints as required by the manufacturer’s instructions
- lack of a 5 mm gap required between the window and door sill flashings and the cladding
- lack of drip moulds on the cladding above the raking window heads along the north elevation
- insufficient ground clearance at some locations to the base of the cladding above the first-floor level balcony decks
- timber fascia above the bay windows being installed directly against the cladding and buried into the plaster
- downpipes discharging onto the decks in a way that channels water onto the cladding.
Compensating factors were found to assist the performance of the cladding. They were:
- generally, the cladding appears to have been installed according to good trade practice
- the exterior windows and doors have effective flashings
- there is no moisture evident in the external wall cavities.
Decision
The house was found to be weathertight and therefore compliant with clause E2. Due to the number of defects to be remedied, the Chief Executive could not be sure that the house will remain weathertight, and therefore will not meet the durability requirements of clause B2 of the Building Code.
The territorial authority’s decision to refuse to issue the code compliance certificate was confirmed.