Fascia-style gutters causing water to run into the building
Guttering can be a hidden leaky building danger in many ‘low-risk’ homes
The perfect storm that culminated in the ‘leaky home’ fiasco was caused by a number of products and processes being introduced into the NZ housing market with totally inadequate testing, validation or approval.
Untreated timber, no cavities, untested leaky cladding systems, leaking windows, complex designs, reliance on sealants… the list goes on.
However one of the biggest and least well known contributors was the fascia-style guttering known as Taylor or Klass fascia which was hugely popular due to the sleek stylish appearance. If you drive around many of the houses constructed in this era, a large number still have this system.
Fascia-style (hidden) guttering systems have a high risk of allowing leaks to come into building walls and cause rot and leaky building syndrome. Because of their design and construction, small defects of installation, or blockages can cause overflows directly into the walls.
Fundamentally, the problem is that the internal lip of the gutter is usually lower than the external lip so that when it overflows, the water can run accross the soffit (if there is one), and into the wall and ceilings.
Often, where a valley in the roof runs into the gutter, the internal edge is notched even lower which becomes the first overflow point. If there are any blockages, excess rainwater during heavy rain will overflow back into the house, often without the owner being aware.
This is a particular problems for owners of plaster clad houses built from 1992 to 2004 where there is unlikely to be a cavity allowing the water to drain away, and the timber is likely to be untreated or undertreated.
We have seen virtually the entire internal framing of the back wall of a house rotted away behind the gib because of persistent overflows of the gutter. Many people aren’t aware that the decaying leaves which block gutters and downpipes often house particularly agressive decay fungi which can cause accelerated rot when overflows wash it into the house.
In traditional externally-mounted guttering systems, these are designed that if there is a blockage somewhere, water will overflow away from the building. This does no harm to the building, and will alert the owner to a problem.