Insurance Claim: Project Managment and Replacement of Large Storm Damaged Tensile Structure.

This project involved the sudden failure of a large tensile membrane during a storm event in October 2016.

The project consisted of a large tensile structure covering an amphitheatre in the grounds of a sporting facility owned by a local Government authority.

The structure was approximately 20 years of age and constructed in an architectural vinyl type fabric with a surface area of 900 sqm meters and was supported by 22 mm perimeter edge cable and attached to 6 perimeter posts.

The project was insured under a broader policy held by the client.

Screenshot of ABC NEWS Twitter page showing damage soon after storm failure.
View of structure after removal

Storm Event and Cause of Damage

The area was struck by a storm event on the day of failure and witness accounts state that the fabric began to tear in one corner which quickly spread to the rest of the membrane surface area which caused the sail to flap in a dangerous and uncontrolled manner within the amphitheatre courtyard.

The area was sealed off by SES and clients staff and the insurer was notified of the situation.

Emergency Removal

Due to the fact the failure occurred on a public holiday the clients on call staff were alerted and attended site to assess the emergency situation.

Due to the size of the structure and the fact it was flapping in the wind the SES sealed of the area from the public and advised the insurer of the issue that required urgent removal by experts.

The insurer immediately contact their specialist shade sail consultants Mainsailz to advise of the issue and seek advice on best method of make safe.

After studying news footage and Twitter feeds of the scene and also Google Earth images of the structure Mainsailz were able to contact a local preferred panel supplier contractor that had the experience and equipment to attend site to remove the sail.

Due to the public holiday closures and the need for specialised access equipment to reach the top of support posts Mainsailz had to engage after hours hire companies to attend site and all of this was completed within 2 hours of receiving the original advice from the insurer.

View of site during removal of the damaged sail structure

First Report

A report from site was then relayed to the insurance case manager who then approved immediate emergency removal of the structure and this work was completed within 1 hour. The insurer then requested a first report and cost estimate from Mainsailz for the replacement of the sail with the claim being accepted under the policy.

The sail was destroyed and required total replacement however due to the size and complexity of the project there were only a handful of specialised contractors capable of undertaking the replacement of the sail and a tender request including detailed specification was sent to two approved contractors within 1 week of the date of loss.

Tender Process and Contract Award

Tenders received were competitive with both using a high quality tensile fabric with completion date of Mid February 2017. After consideration the tender deemed to be confirming was accepted by the insurer with Mainsailz project managing the contract on behalf of the insurer.

Site Survey

The successful contractor was able to travel to site within 2 weeks of receiving the order and engaged a surveyor to fully measure the total project to ensure accuracy when modelling new sail. This information is then loaded into a specialised software program that models and patens the new sail to ensure it fits exactly when installed.

Drone view during site survey

New Sail Modelling and Design

Due to the fabrication timeline running into the Christmas holiday period it was decided to order the fabric and complete all the computer patenting required to fabricate the new sail prior to Christmas with fabrication of the new sail commencing immediately after the Christmas break. The Council was constantly updated on progress and timelines for completion.


The sail was fabricated in a specialised membrane manufacturing facility using Formfinder software and HF fabric welding machines. The mode of fabrication consisted of each roll of fabric being inspected for faults then placed on a fabric cutting bench to allow each individual panel to be cut to size using the CAD software modelling program.

These panels are then numbered and welded together to form on large membrane. The edge pockets are then welded and the corners finished. Due to the size of the sail several staff were needed to move it within the fabric welding machines and when packing.

Fabrication was completed ahead of time and carefully packed before being loaded into a custom designed shipping container that is then locked and delivered directly to site to avoid any damage that can occur with general freighting options.

Packing and Freight To Site

After manufacture the sail is carefully folded to an exact plan to allow easy installation on site. It is the wrapped in heavy duty packing fabric and stored into a special shipping container that is locked and delivered direct to site. This method ensures that there is no damage during freight.

Weather Forecast Modelling

With any tensile membrane of this size it is important to only install when the weather is calm so the installation crew began to look at long range forecasts several days out to allow for installation to occur in ideal conditions.

The area is prone to weather fronts passing through every few days and installation was times to occur in between these weather fronts.

Wind Graph

Site Set Up

The installation process was undertaken 1 week sooner than expected and was completed in two days using 2 x cranes and 4 x scissor lifts.

A mobile workshop fitted out with the various speciality components required to carry out these type of complex installations was delivered to site and specialised riggers were contracted to assist with the project installation.

The site was fenced off to stop public access to the work area and a large groundsheet was firstly laid out to protect the new fabric which was then positioned above the job area using cranes.

Sail Installation

Works to install the sail commenced at 5 am to take advantage of the low winds speeds that normally occur early in the day. Using a combination of cranes and knuckle booms each corner was lifted into position and attached to their respective post attachment point. Once each point was attached final tensioning of the pocket cables were completed with each corner then being locked off.

Completed Project

The new sail fitted exactly and Council officers were extremely pleased with the way the claim was handled from start to finish and also impressed with the quality of the replacement product.

A final on site inspection and handover was undertaken by Mainsailz staff on behalf of the insurer and a detailed inspection report was included.

Fabric warranty ( 20 year ) documents were signed off on by the manufactures and included in the complete project portfolio that was delivered to council for their records.