The evidence of the experts
47The evidence given by Mr Brent Guest was as follows :
Inspection and Comments
A site inspection of the existing timber framed mezzanine structure was carried out on Tuesday 21 st September, 2010, in the presence of Mr Graham Scheffers of GRS Building Reports Pty Ltd (Building code of Australia (BCA) consultant), Ms Karlie Bombardier of Bombardier Real Estate, Mr Dale Martinuzzo of Warringah Council, and the existing tenants.
The existing timber framed mezzanine (Photo No. 1) has been checked and we advise that the existing timber joists (190 x 45 Oregon spaced at 450mm centres) are structurally adequate to support a live load of approximately 5 kPa (500 kg per square metre) which is equivalent to a storage loading as detailed in the SAA Loading Code AS1170.1. However, the supporting timber bearers (190 x 45 Oregon) are only adequate to support a live load of 1.5 kPa (150 kg per square metre) which is equivalent to the loading for a domestic floor as detailed in the SAA Loading Code AS 1170.1. Should the timber mezzanine be retained and used for storage then the existing timber bearers will need to be strengthened or replaced and upgraded to larger member sizes to suit any storage loadings greater than 1.5 kPa (150kg per square metre).
The connection of the existing timber wall plates (supporting the timber floor joists) into the masonry walls could not be accurately determined on site. As such, we would recommend the installation of new connections - M12 masonry anchors installed at approximately 500mm centres with 80 mm minimum embedment. This will ensure all timber wall plates are structurally adequate to support the required floor loadings of between 1.5 and 5 kPa.
The existing timber framed mezzanine structure in its current state does not have a fire resistance level (FRL). The BCA Consultant would need to confirm the required fire resistance level of the mezzanine to satisfy the provisions of the BCA. If an FRL of 60/-/- for the columns and 60/60/60 to the underside of the mezzanine was specified, then the timber columns and underside of the mezzanine floor would need to be clad with a suitable proprietary fire rated cladding that meets the specified FRLs.
The existing mezzanine balustrade (Photo No. 2) was measured by the BCA Consultant and found to be less than 1 metre in height. We also checked the existing upper level balustrade and found it to be poorly constructed and structurally unsound. We advise that the existing balustrade needs to be removed and replaced with new either a new BCA (Building Code of Australia) compliant balustrade or a full height timber stud wall connected to the existing ceiling structure. This work needs to be carried out in order for the mezzanine to be considered structurally adequate.
Conclusion
The existing timber framed mezzanine is considered structurally adequate to support a superimposed Live Load of only 150 kg per square metre. If heavier loads are required to be imposed upon the structure, then the existing timber bearers need to be replaced and upgraded.
The existing mezzanine balustrade is structurally unsound and needs to be replaced with a BCA complaint balustrade in order for the mezzanine to be considered structurally adequate.
The installation of proprietary fire rated cladding is required in order to achieve a fire resistance level (FCL) to satisfy the provisions of the BCA. This will ensure the mezzanine is structurally adequate and complies with the fire provisions of the BCA.
48The evidence of Mr Graham Scheffers was as follows:
3. Options
3.1 The Orders requires actions in relation to the use of the subject premises in addition to the demolition of the subject mezzanine and removal of the kitchen facilities. The primarily purpose of this Statement is to provide comments and assessment in relation to the construction of the Mezzanine as I understand that the removal of kitchen facilities and use of the premises are being dealt with separately by the parties involved.
3.2 In relation to demolition of the subject mezzanine, I consider that an alternative option is to use the provisions of Section 149A to 149E of the Environmental Planning & Assessment Act, 1979 (NSW). These provisions enable the owner to lodge an application for a Building Certificate and for Council to issue a Building Certificate for the mezzanine. The effect of a Building Certificate as stated in Section 149E is that:
(1)A building certificate operates to prevent the council:
(a)From making an order (or taking proceedings for the making of an order or injunction) under this Act or the Local Government Act 1993 requiring the building to be repaired, demolished, altered, added to or rebuilt",
3.3 The provisions of Section 149A to 149E allow for the mezzanine to be accepted by Council, subject to any upgrading that may be required. I am of the opinion that this is an appropriate alternative action to the mezzanine being demolished. On that basis, in July 2010, I requested that a joint meeting be arranged on site with Council's Development Compliance Officer (Dale Martinuzzo), the owners representative (Karlie Bombardier), a structural engineer (Brent Guest) and BCA Consultant (Graham Scheffers) to enable a detailed inspection of the mezzanine for the purposes of determining if it was feasible for the mezzanine structure to be retained and a Building Certificate issued.
4. BCA Compliance
4.1 I carried out an inspection of the mezzanine, the subject of Council's order on 21 September 2010 to enable an assessment of the structure against the relevant provisions of the Building Code of Australia.
4.2 A photograph of the mezzanine that was identified by Council's Development Compliance officer is included as Figure 1 below. I took this photograph of the mezzanine at the time of the inspection on 21 September 2010.
4.3 I am of the opinion that if the following items at paragraphs 4.4 to 4.7 are addressed, the timber mezzanine would be acceptable to remain, subject to a Building Certificate being issued by Warringah Council.
4.4 To address the BCA Part B (Structural Adequacy) provisions a separate report is to be provided from Brent Guest (Structural Engineer) to confirm the structural adequacy of the existing mezzanine and provide recommendations where necessary on upgrading works that may be necessary. Once upgrading works are complete a follow-up inspection and verification must then be obtained to confirm the structural adequacy of the mezzanine structure.
4.5 To satisfy the provision of BCA Part C for Fire Resistance Level (FRL), the mezzanine is required to be provided with the following FRL's to satisfy Table 3 of the BCA Specification C1.1:
Columns - FRL of 240/-/-, and
Floor - FRL of 240/240/240.
Notwithstanding this, the provisions Clause 2.6 of Specification C1.1 of the BCA provides a concession to small mezzanines that are less than 1/3 of the floor area of the room in which it is located, subject to the walls and columns within 6m of the mezzanine achieving an FRL of 240/240/240. The concession is to enable the mezzanine and its supports so that they need not have an FRL or be non-combustible. I offer the following comments in consideration of the FRL's.
4.5.1 The purpose of these provisions of the BCA is to increase the FRL's surrounding a mezzanine that is combustible to recognize the increase in the fire load that may exist within both the mezzanine and storey as a whole. The structural walls adjoining the subject mezzanine, are of masonry construction and were required to be provided with a 4 hour Fire Resistance Rating as a result of Condition 15 of the Building Approval No 3199/86 dated 15 December 1986 that states that:
"The building being constructed in Type 1 construction in accordance with the provisions of Part 16.7 of Ordinance 70".
This equates to the current FRL of 240/240/240. the construction of the existing walls to achieve the Fire Resistance Rating required at the time of construction has been assumed only and has not been verified.
4.5.2 The timber mezzanine has a floor area of approximately 16m and the room in which the mezzanine is located has a floor area of approximately 160m . On the basis that the mezzanine is approximately 1/10 the floor area of the room it is located, which is substantially less than 1/3, the mezzanine is unlikely to significantly contribute to the fuel load of the space.
4.5.3 In order to minimise this impact and having regard to the surrounding wall construction being masonry, I considered it is reasonable for the mezzanine to remain subject to the columns and underside of the flooring being provided with an FRL of 60/-- and 60/60/60 respectively. This will result in the critical elements of the mezzanine structure to not contribute to the fire load for at least a period of 60 minutes that is equivalent to the current provisions of BCA Specification C1.1, Clause 3.7 for walls and columns located in the storey below the roof where the building has a rise in storeys of more than 3.
4.6 To satisfy the BCA Part D (Balustrade Construction) provisions, a floor must have a balustrade at least 1.0m in height. The existing balustrades have a height of approximately 960/ 970mm above floor level. I consider it appropriate that the height of the balustrades be increased to at least 1.0m to satisfy the provisions of BCA Clause D2.16. The existing balustrade has a solid plywood balustrade so that there are no gaps and this satisfies the provisions of BCA Part D - Balustrade construction.
4.7 To satisfy the BCA Part F (Ceiling Height) provisions, the mezzanine must have a ceiling height of at least 2.4m if used as an office or workspace and at least 2.1m if used for storage. The mezzanine has a ceiling height ranging from approximately 2.33m to 2.38m to the ceiling above and approximately 2.5m to the underside of the mezzanine. I consider that the area below the mezzanine satisfies the provisions of BCA part F (Ceiling Height). Subject to the floor of the mezzanine being used for storage only, this satisfies the ceiling height provisions of BCA Clause F3.1.
5. Conclusion
5.1 I am of the opinion that an alternative option to demolition of the timber mezzanine is for the structure to remain subject to the actions in paragraphs 5.2.1 to 5.2.5 being carried out to satisfy the relevant provision of BCA in relation to structure adequacy, minimising the risk of falls, providing an FRL to the degree necessary and permit ceiling heights suitable for the use of the space concerned.
5.2 The lodgement of the application for a Building Certificate will seek to address the status of the mezzanine as an unlawful structure and seek to have the mezzanine retained. The other issues in Council's Order dated 3 June 2010 in relation to the kitchen and use of the premises with the exception of paragraph 5.2.5 below has not been included in this statement as I understand these issues are being dealt with separately. Actions to be undertaken are:
5.2.1 Lodge a Building Certificate (S149A) application with Warringah Council to seek to have the timber mezzanine retained and the Order rescinded.
5.2.2 Obtain a separate report from a Structural Engineer to confirm the structural adequacy of the existing timber mezzanine and provide recommendations where necessary on upgrading works that may be necessary. Once upgrading works are complete a follow-up inspection and verification must then be obtained to confirm the structural adequacy of the mezzanine structure.
5.2.3 The columns and underside of the flooring being provided with an FRL of 60/-/- and 60/60/60 respectively.
5.2.4 The height of the mezzanine balustrade must be increased to at least 1.0m. The existing balustrade infill panels are to be retained and if modified must satisfy the requirements of BCA Clause D2.16 in relation to any gaps.
5.2.5 The floor of the mezzanine being used for storage only. The Building Certificate is to specify this as a limitation on the use of the space.
This report is limited to addressing the existing timber mezzanine only and is not intended to provide a BCA assessment of Unit 10 or the remainder of the building.
49Somewhat curiously the defendant did not take the Court in detail to these reports but left it for the Court to understand matters of some complexity.
50I was left by both reports with the view that notwithstanding the reports, there could not be said to be a certainty that the mezzanine would not have had to be torn down anyway. This is clear from Mr Scheffer's evidence, that the primary order was for demolition and to avoid this result required an application for a building certificate. The granting of this certificate was by no means a certainty.