Challenges in remediation

This Issue This is a part of the Weathertightness feature

By - , Build 110

Maintaining the architectural integrity of a building while improving its performance is just one of the challenges of weathertightness remediation.

What differentiates a ‘leaky building’ from a building that happens to leak? A leaky building is where the cladding system, including roofs, decks and windows, is inherently unsound. Hence, the remediation process has to address both the leaks and the inadequacy of the cladding system. Typically for monolithic clad buildings, this means adding a drained and vented cavity.

There are many challenges with remediation, such as the design of repairs to configurations and designs that should have been avoided. Maintaining the architectural integrity of a building while improving its performance and helping its owners can be most satisfying.

Redesign, demolish or sell as is?

The primary goal with any repair is for the owner (present or future) to have confidence that the building will perform adequately into the future. To achieve this, knowledgeable and experienced people are needed to design and repair the building.

Owners want value for money, while achieving the required outcomes. Repairs can become uneconomical, and sometimes it may be better to demolish and rebuild, or to sell ‘as is’.

Even after being repaired, buildings that look like leaky buildings, or use materials associated with them, may suffer a loss of value through the stigma attached to leaky buildings, so a degree of redesign is usually sensible.

At Prendos, we have always recommended repairing buildings first, so that people can get on with their lives. This approach provides the best evidence of cause and cost of repair. We also favour a team approach of client, consultant and contractor, all working together to fulfil their tasks and responsibilities.

The legal side

Legal requirements govern behaviours in the remediation field. These can be in the form of statutes like the Building Act and our performance-based Building Code. The Weathertight Homes Resolution Service Act effectively allows legal action to begin at little cost to the owner. Unfortunately, the latter has become the bane of many within the industry.

The Contractual Remedies Act covers misrepresentation. A vendor is responsible for reinstating the building to the standard that it was represented to be, even if the misrepresentation was made innocently and in good faith by them or their agent.

Another trap for the unwary is the warranty provisions within a standard sales and purchase agreement. Effectively, a vendor guarantees that the building meets the Building Code. If it is a ‘leaky building’, there can be severe ramifications for the vendor.

Technical aspects straightforward

The technical aspects of leaky buildings are more straightforward. Weathertightness principles such as the four Ds, pressure equalisation and risk assessment come to the fore.

It must be remembered that E2/AS1 solutions were developed around buildings with treated framing. Remediation of buildings that contain untreated framing requires extra care and diligence, as these buildings are inherently less durable. While treating the exposed faces of framing with chemicals helps, decay can easily remain hidden, either behind or within timber.

We have already seen the first instances of so-called remediated buildings failing, as those involved in the repair did not appreciate what they were seeing and working with. Knowledge of durability issues, such as corrosion, timber decay and mould growth, is essential. So is knowledge of brown rots, their identification and behaviour. With many buildings constructed of untreated Pinus radiata, this is a key to understanding remediation.

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