Modern homes have a much shorter lifespan than many of their owners appreciate, construction law expert Tanya Wood says.

New home owners have little idea that construction materials such as cladding and windows are only required to last for 15 years, Wood says.

Builders, designers and developers are grappling with planned changes to the Building Act over the lifespan of materials, builder qualifications, and liability when things go wrong.

Wood says the construction scene is an "industry of disputes", based on cases she has dealt with in the courts about building materials and the way they were installed.

"When I commute to work and see all the new subdivisions on my way, I ask myself how many homeowners know they might be facing re-cladding and other replacements within 15 years.

"Compare modern homes with the materials and craftsmanship of a 100-year old villa - the modern home is built to last 50 years."

Wood says that in her experience, cladding and window joinery often don't meet even their required 15-year longevity, sometimes because of quality, and installation.

Wood says standard aluminium joinery companies mostly provide a five-year warranty.

But if window joinery fails and has to be replaced it often requires removal of the exterior cladding too.

A plywood-based cladding material called Shadowclad has been the subject of court disputes for more than five years. Complainants say it is not fit for purpose.

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