Designing to encourage maintenance

This Issue This is a part of the Claddings feature

By - , Build 109

Maintenance-free buildings are a misnomer – all buildings need maintenance to remain functional. To support this, designers should design buildings that allow inspection and regular maintenance, ideally without the need for specialist equipment.

Having areas of wall and window that can’t be reached by washdown brushes makes washing claddings for maintenance difficult.

The mythical building that requires no maintenance does not actually exist. All buildings will need parts replaced periodically, but the replacement period for some elements is longer than for others. Regular inspections are needed to detect any elements that need attention, but some designs make this extremely difficult.

Legislation refers to maintenance

The Building Act 2004 includes, as a principle, taking account of ‘the importance of ensuring that each building is durable for its intended purpose’ and, for household units:

  • ‘the need to ensure that maintenance requirements of household units are reasonable’
  • ‘the desirability of ensuring that owners…are aware of the maintenance requirements’.

The Act also directs us to take account of the whole-of-life ‘costs of a building (including maintenance)’.

This principle is expressed through regulation and the durability provisions of the Building Code, which require that, ‘building elements must, with only normal maintenance, continue’ to comply with the Building Code. What constitutes ‘normal maintenance’ is not defined in the regulations.

So what is normal maintenance?

Manufacturers and suppliers of building elements should provide technical literature describing the maintenance regime required for their product to perform to expectations. It is generally understood that the maintenance regime described by the manufacturer is considered to be normal for that particular product.

As part of the consenting process, the Building Consent Authority must agree that the level of care recommended by the manufacturer and the access on site to undertake maintenance is reasonable.

Having areas of wall and window that can’t be reached by washdown brushes makes washing claddings for maintenance difficult.

Why is maintenance necessary?

Problems can arise when an owner fails to undertake the recommended maintenance. Assessments undertaken by the Weathertight Homes Resolution Service show that some leaks have been caused, or exacerbated, by a lack of maintenance. Making the owner aware of the on-going maintenance requirements at the design stage allows different options to be assessed. The owner can then make a commitment to these costs.

But often the building owner doesn’t read through the detail of the building consent and doesn’t understand what maintenance is required. Subsequent owners are even more remote from the consenting process. It is therefore recommended that a maintenance manual is compiled for the initial owner of the building and passed on to subsequent owners.

How long must building elements last?

Building Code Clause B2 Durability provides for building elements to achieve not less than 5, 15 or 50 years satisfactory performance with only normal maintenance. The category each element falls into is decided by:

  • the ease of detecting failure during normal use and maintenance
  • the ease of access to the element to replace it if it does fail
  • whether or not the element provides structural stability to the building.

The Building Code performance requirements are a minimum standard. Often the durability requirements of the Building Code fall short of the owner’s expectations of serviceable life.

Typically, roof and wall claddings need to achieve a durability of not less than 15 years, but owners won’t expect to replace the cladding in this timeframe. Public expectation is that buildings will be sustainable, the emphasis being on retention of materials with high embodied energy. It therefore makes sense for building designs to faciliate replacing building elements as they reach the end of their serviceable life, or to modernise their appearance.

Designing claddings for maintenance

Designers need to address maintenance issues that may be created by the building itself. For example, complicated roof forms incorporate more roof plane junctions, such as valley gutters, that may require additional maintenance – is it feasible and safe to inspect and clean out gutters? Small wall sections between roof planes can be difficult to build and even more difficult to access for maintenance.

Regular washing is important to maintaining the cladding of buildings – can all the wall and window areas be reached with commonly available washdown brushes? With wider eaves to deflect water from the cladding surfaces, access is especially important to manually wash areas not adequately washed by rain.

In deciding the appropriate durability of an individual element, designers should consider ease of access to inspect, maintain and replace elements. For example, designing a sealant joint with a sealant that has a short life is permissible as long as the sealant can be seen at close range and can be readily removed and replaced periodically.

It will not satisfy the Building Code if it is on a part of the building that needs specialist scaffolding to access, as may be the case for taller buildings, or for buildings on steep sites. Neither will it satisfy the Code if it is shielded from view and failure cannot be detected, such as when placed behind a joinery flange, or a weathertight cladding joint that is overlaid with a decorative screening wall. Can the bolts connecting the spandrel panel to the frame be inspected for condition without removing some of the internal lining?

Many cladding systems will need recoating throughout the life of the building to meet the durability provision – does the design allow this recoating to be carried out? Many newer houses can be difficult to scaffold for recoating as they have upper wall faces that are inset from the floor below and a roof cladding that is not designed for maintenance traffic.

Waterproof membranes to decks can be problematic to recoat at the wall and balustrade upstands. Can the membrane be inspected and maintained where tiles are overlaid?

Designers pass information to owners

To effectively maintain the claddings of their building, owners need to know the specific products that are used and the manufacturer’s recommendations for inspection and maintenance. Including any warranties and details of those involved in the initial installation of the product can be helpful.

Buildings must be designed to allow maintenance to be effectively carried out. Products should be durable and have realistic levels of maintenance. Owners need to be aware of the maintenance requirements and be diligent in carrying out that maintenance. If this is done, well-maintained buildings will last longer and look better.

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Having areas of wall and window that can’t be reached by washdown brushes makes washing claddings for maintenance difficult.