Fascia-style gutters causing water to run into the building
Guttering can be a hidden leaky building danger in many ‘low-risk’ homes
Fascia-style (hidden) guttering systems pose risks of causing leaks to come into building walls and cause rot and leaky building syndrome. Because of their design and construction, small defects of installation or blocked drainpipes can cause overflows into the building. For example the back edge of the internally-mounted plastic guttering system may be cut too low and this becomes the first overflow point. Similarly over time the plastic can warp, causing low points along the wall. Excess rainwater from a blockage during heavy rain will overflow at low-points first. Then it will track where the surrounding materials guide it. If the surrounding soffit has even a slight tilt towards the house, this directs substantial amounts of roof water run-off into the walls and ceilings, causing leaks and encouraging rot. Unless the owner is aware of this happening, it could continue for years unnoticed.
An example where the fascia-style guttering has overflowed or leaked causing moisture to build up on the soffit liner. It is unclear whether water has entered the building walls. Mold can be seen growing on the soffit liner at the multiple locations where the gutters leak
Compare this design approach to traditional externally-mounted guttering systems. These are usually designed as ‘fail-safe’ in 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.