The house in Herculaneum is not mostly new construction, this is well documented and can be easily researched. This house was discovered mostly intact with furniture and cupboards filled with everyday fare. What you see of this house is mostly what was originally there. There was a very small amount of restoration done to keep it in fairly reasonable shape, but the vast majority of the structure dates to its construction some time after 68 AD. It is considered to be the only fully intact example of this style of building still in existence.

Still this is not entirely fair. The building was buried in ash with pockets of poisonous gasses, preserving it in a moment of time. It's not a testament to the longevity of the style -which even if it is not the same style Vitruvius calls Opus Craticium was still reserved only for the cheapest construction in Roman Italy (we deduce this by the fact that all of the finer buildings are made of stone and brick). If it were not in the perfect place at the perfect time, this building would likely have suffered the same fate as every other example of this the Romans ever built -it would have fallen down.