- June 13, 2014
Remedial works to concrete podium slab including re-membraning, landscaping, and concrete spalling repairs of approximately 500m2 by Strata Engineering Solutions in 2014. Strata property at New South Head Road, Double Bay NSW.
PROBLEMS
The existing podium slab, located towards the front of the building, was leaking significantly into the car park area below. Water was cascading down from the construction and movement joints. The temporary measures to divert the water ingress, such as gutters and pipes, had also failed. Concrete spalling and severe corrosion of the reinforcement was evident at the underside of the slab. Some areas of the exposed membrane above were deteriorated.
SOLUTIONS
Strata Engineering Solutions were the design engineers who prepared the specification for remedial works. SES prepared the tender documentation and the contract between the preferred contractor and the owners. SES was then engaged to project-manage the remedial works, and execute the contract.
Initial visual assessments by SES engineers indicated that the most likely cause of the water ingress and associated problems was a failed waterproofing membrane below. However, before preparing a specification for the works, SES conducted intrusive investigations to confirm the original assessment and to determine the extent of the work required. It was confirmed that the membrane had failed in numerous locations. Not only was the membrane itself distressed, but the detailing around the movement and construction joints had failed also. SES then developed design documentation and specification for the remedial works. The scope of works was tendered for pricing from 3 specialist remedial contractors. SES reviewed the tenders submitted and provided recommendations to the owners.
The remedial works included the full removal of the landscaping and vegetation above. SES removed the existing distressed membrane back to the bare slab. SES then carried out concrete repairs both to the top and bottom of the concrete slab. All the joints were detailed and the podium slab re-membraned in 2 stages using a 2 layer anti-root torch on the membrane. Drainage cells and sand layers were incorporated in the design for the new landscaping on top. Newly tiled areas for the three ground floor units were also carried out. The garages below were all repainted and new turf and mulch were installed.
RESULTS
On completion, the building owners were able to enjoy a beautifully finished landscape podium deck that is more usable, a concrete roof slab that does not leak into the car park below, and the peace-of-mind provided by the reinstatement of the structural integrity of the reinforced concrete podium slab.
- Concrete Defects
- Water Damage
