Determination in Respect of Building Design - An application made under s 160A of the Building Act 1993 for a determination that the design of the roof drainage system for the Unit - 2 (Class 1a), wherein, the sump overflow from the box gutter system discharging into a 'faux' rainhead and the spreaders discharging storm water from upper roof on to the lower tiled roof that has not been provided with a sarking medium underneath the roof tiles, and also the rainhead installed at the front and rear of the garage including the downpipes complies with the Performance Requirements P2.2.1 and P2.2.2 of the BCA.

APPLICANTS Jefta Ongkodiputra and Kumala Sumarni (Subject Land owners)

INTERESTED PARTY Castle Kane Group Building Surveyors Pty Ltd (ACN 634 101 063) (relevant building surveyor)

BEFORE Members J Shaw (panel chair) and L Varveris, B Williams

CITATION In the matter of 15 Jessup Close, Mulgrave [2025] VBAB 55

Having considered all the submissions and information placed before it, and having regard to the Performance Requirements P2.2.1 and P2.2.2 of the Building Code of Australia 2019 - Volume Two (BCA), pursuant to s 161 of the Building Act 1993, the Building Appeals Board determines that:

1. In relation to Application 1, there is compliance with the Performance Requirements P2.2.1 and P2.2.2 of the BCA.
2. In relation to Application 2, there is compliance with the Performance Requirements P2.2.1 and P2.2.2 of the BCA.

_______________________ ________________________

APPEARANCES AT THE E-HEARING DATED 8 NOVEMBER 2024

For the Interested Party Mr S Maloney, representative

APPEARANCES AT THE E-HEARING DATED 4 MARCH 2025

For the Interested Party Mr S Maloney, representative

1. The Applicants own the land at 15 Jessup Close, Mulgrave (Subject Land).
2. They are having two dwellings constructed on the Subject Land (Building Work), and the dwellings are referred to as 'Unit 1' and 'Unit 2' (or, together, the Units). Both Unit 1 and Unit 2 are Class 1a dwellings pursuant to the Building Code of Australia 2019, Volume Two (BCA).
3. The Interested Party, Castle Kane Group Building Surveyors Pty Ltd, is the relevant building surveyor (RBS) appointed in respect of the Building Work.
4. A hearing was held on 4 March 2025, where the following three proceedings were heard concurrently:

a) Proceeding 455800, which is an appeal made under s 138(1)(a) of the Building Act 1993 (Act) against the refusal or deemed refusal of the RBS to issue an occupancy permit in respect of the Building Work; > > b) Proceeding 455998, which concerns two applications, one for each unit, made under s 160A of the Act for a determination that a plumbing performance solution in respect of the roof drainage systems for each Unit complies with the Performance Requirements P2.2.1 and P2.2.2 of the BCA; and > > c) Proceeding 456378, which concern two applications, one for each Unit, made under s 160(2)(b) of the Act to modify Performance Requirements P2.2.1 and P2.2.2 of the BCA to allow the as-constructed roof drainage systems to remain instead of requiring the construction of the roof drainage systems indicated on the drawings forming part of the building permit for the Building Work.

5. The applications made in proceeding 456378 in paragraph (c) above is made as an alternative to the applications made in proceeding 455998 in paragraph (b) above.
6. This determination is made in respect of the applications made under s 160A of the Act in proceeding 455998 and also in respect of the alternative applications made under s 160(2)(b) of the Act in proceeding 456378.

1. The RBS issued a building permit dated 30 March 2021 for the Building Work (Building Permit). The Building Permit identifies that the 2019 version (presumably Volume Two) of the BCA applies to the Building Work (BCA 2019).
2. The drawings that formed part of the Building Permit required the roof drainage system of the Units to be carried out in accordance with the Deemed-to-Satisfy (DtS) requirements of the BCA 2019.
3. After the Building Permit had been issued, the Building Work was carried out. In early September 2023, the RBS was requested to carry out a final inspection of the Building Work, which he did on 11 September 2023.
4. In the inspection the RBS identified, inter alia, that the roof drainage system had not, in a number of respects, been constructed as required by the Building Permit and did not comply with the DtS requirements of the BCA 2019.
5. As a consequence, the Applicants have had performance solutions prepared for the Units, and they seek a determination of the BAB that the performance solutions comply with the relevant performance requirements of the BCA 2019.
6. The performance solution for the roof drainage system for Unit 1 is set out in a report prepared by Robert Woolley dated 10 May 2024 titled 'Roof Drainage Alternate Overflow Measures Performance Solution', together with an addendum dated 27 July 2024 titled 'Addendum to Performance Solution for Unit 1-15 Jessup Close Mulgrave' and a second addendum dated 29 November 2024 (Unit 1 Performance Solution).
7. Mr Woolley is, amongst other things, an experienced plumber.
8. In the hearing, Mr Woolley confirmed that he had inspected the Building Work, and that the Unit 1 Performance Solution reflected the as-constructed roof drainage system. Mr Woolley carried out calculations to determine that the Performance Requirement P2.2.1 of the BCA 2019 have been met by the roof drainage system set out in the Unit 1 Performance Solution. He also considered the use of a product called 'Deks Fast Flash', which is fixed according to the manufacturer's recommendations to the surface of the roof tiles, instead of sarking, in the vicinity of roof drainage spreaders discharging onto a roof, and concluded that, as a result of his expert opinion and consideration of the suitability of the product, it complies with the Performance Requirement P2.2.1 of the BCA 2019. In the second addendum dated 29 November 2024, Mr Woolley includes a table that sets out the issues that the Unit 1 Performance Solution addresses, and confirms that it meets the Performance Requirements P2.2.1 and P2.2.2 of the BCA 2019. The Unit 1 Performance Solution is stated to be subject to the following conditions in respect of the section of guttering behind the entrance roof:

a) the spreader behind the entrance roof should not be installed to discharge above the vertical overflow, and in addition access should be provided for maintenance; > > b) the other end of the gutter should discharge adjacent to the tiles, and the current tiles need to be removed and replaced with a suitable small gutter more than 100mm wide and 40mm deep that discharges to the eaves gutter; > > c) the flexible flashing material installed and placed over the base of the gutter needs to be removed; and > > d) liquid rubber, or a suitable alternative, needs to be applied to the bottom of the tile ride capping in order to waterproof the connection of the roofing and gutter components.

9. The performance solution for the roof drainage system for Unit 2 is set out in a report prepared by Robert Woolley dated 3 May 2024 titled 'Roof Drainage Alternate Overflow Measures Performance Solution', together with an addendum dated 9 August 2024 titled 'Addendum to Performance Solution for Unit 2 15 Jessup Close Mulgrave' and a second addendum dated 29 November 2024 (Unit 2 Performance Solution).
10. In the hearing, Mr Woolley confirmed that he had inspected the Building Work, and that the Unit 2 Performance Solution reflected the as-constructed roof drainage system. Mr Woolley carried out calculations to determine that the Performance Requirement P2.2.1 of the BCA have been met by the roof drainage system set out in the Unit 2 Performance Solution. He also considered the use of a product called 'Deks Fast Flash', which is fixed according to the manufacturer's recommendations to the surface of the roof tiles, instead of sarking, in the vicinity of roof drainage spreaders discharging onto a roof, and concluded that, as a result of his expert opinion and consideration of the suitability of the product, it complies with the Performance Requirement P2.2.1 of the BCA 2019. In the second addendum dated 29 November 2024, Mr Woolley includes a table that sets out the issues that the Unit 2 Performance Solution addresses, and confirms that it meets the Performance Requirements P2.2.1 and P2.2.2 of the BCA 2019.
11. The Applicants also engaged Mr David Robinson of Robinson Engineering Consultants to provide a peer review of the Unit 1 Performance Solution and the Unit 2 Performance Solution, and that review is dated 7 January 2025 (Robinson Review).
12. Mr Robinson is a registered professional engineer with more than 40 years' experience in building services engineering, with considerable experience in roof drainage systems.
13. Mr Robinson inspected the roof drainage systems of units 1 and 2, and reviewed the performance solutions prepared by Mr Woolley. As a result of his review, Mr Robinson concludes that both performance solutions prepared by Mr Woolley comply with the relevant performance requirements of the BCA 2019.
14. In addition to the Unit 1 Performance Solution, the Unit 2 Performance Solution and the Robinson Review, the Applicants have also filed two Compliance Certificates dated 12 July 2024 and 15 November 2024 respectively made under s 221ZH of the Act (Compliance Certificates). In the Compliance Certificates, the certifying plumber certifies that the work carried out 'as per the performance solutions provided by Robert Wooley [sic] - Plumbing Performance Solutions' was carried out by him, and that it complies with the plumbing laws as defined in Part 12A of the Act.
15. Having considered the documents that form the Unit 1 Performance Solution and the Unit 2 Performance solution, together with the Robinson Review, we find that the design of the roof drainage systems set out in the Unit 1 Performance Solution and the Unit 2 Performance Solution comply with the Performance Requirements P2.2.1 and P2.2.2 of the BCA 2019. We are further fortified in our conclusion by the existence of the Compliance Certificates in respect of the work carried out. Consequently, the application made under s 160A of the Act succeeds.
16. Given this conclusion, the application made under s 160(2)(b) is refused, as no modification is required.