Weathertight Remediation: An introduction for builders


This is the seventh article in a series based on a number of workshops on weathertight remediation for builders which the Ministry of Business, Innovation and Employment – Building and Housing group has been running at centres all over New Zealand.

In previous articles, we have mostly looked at pre-start considerations. In this article we will be looking at some of what builders need to think about when we are underway on site. Re-cladding projects are like renovations on steroids — there are very few aspects of the house that won’t be affected.
It is a very stressful time for the home owner. All they typically get at the end of it is the house they thought they bought in the first place, and all they have to show for it is usually a bigger mortgage.

It is not just the home owner who is effectively the client. Their funder has a vested interest in restoring value in their collateral. The territorial authority, along with the Government, may also be contributing if the client is participating in the Financial Assistance Package scheme.
On multi-unit sites, a body corporate will be involved, and usually an elected building committee will represent all of the owners.

Whether the building occupants are going or staying can make a significant difference to the operation and efficiency of a project.
Some owners may not have the desire or the means to vacate their home. If they are vacating, will they be taking their chattels, too, as there may be insurance implications for them remaining?

It is also much more efficient if household items don’t have to be moved or protected during the repair process.

Second generation repairs
As has already been seen in Canada, where they have been dealing with a similar problem for 20 years, we are already carrying out second generation repairs in New Zealand.
As we all know, we builders carry significant latent liability for our work. Therefore it is critical to minimise any risks and consequences of future failures. Getting the repair done right is simply the best way to achieve this.

Working with suitably experienced professionals is critical. A builder should expect a designer to
provide details that are timely, that work and are appropriate.
The law is getting much clearer on this. If the builder comes up with his own detail or builds something that is on the plans that they know will possibly fail, who is liable if it does?

Builders, myself included, are not exactly well known for their paperwork, but good record keeping helps variation management, and really helps resolve current or future potential disputes.
In addition, documenting all the damage discovered with location-specific photographs builds a historical record of what was found. Quality control systems and good site supervision can assist in catching even minor errors or omissions in the rebuild process that could otherwise accumulate and contribute to future building failures.

Discovering as much damage as early as possible allows budgetary implications and design clarifications to be dealt with right at the start. This is especially important if the damage is worse than initially assessed.
On every project I have been involved with, there is at least some degree of non-compliant work discovered in the original structure. How is this dealt with?
Other things to consider include the temporary bracing that may be required as the removal of bracing (either external or internal) or removal of cladding to allow for concrete nib installation may affect the integrity of the structure.

A fundamental question for most remediation projects is what timber to leave in, treat insitu or replace. There are many types of timber rot and ways of testing for them. Visual and strand tests, for example, have their uses but also their limitations.

The only way to be absolutely certain of its type and history is a lab test.
Some rots are visually hard to detect, and timber sampling of what appears to be sound wood (even if only as a datum) can help prevent the consequences of leaving structurally unsound timber behind.

Having suitably qualified and experienced experts to interpret and instruct not only helps with compliance, but could also potentially help narrow a builder’s related latent risks.
If builders have doubts about what has been instructed they can simply get testing carried out themselves as an inexpensive form of insurance.
As with risks on any type of project, understanding the risk is key to managing it.

Wrap Up:
Our penultimate article goes back to basic first principles of weathertight design to get a better remediation solution.

Suggested follow up areas for more information:
• Building and Housing web site:
• The Building and Housing publications
• Guide to Remediation Design
• Guide to the Diagnosis of Leaky Buildings
• Dealing with Timber in Leaky Buildings
• Code Watch Issue 1: October 2011

• The author: Harry Dillon has been involved with the repair of more than 300 homes as a builder over the past 10 years. This article represents Harry’s views which may not necessarily be the same as the Department’s.