Box gutter design for Sydney simplified 

How much do you know BOX GUTTERS?
There are two types of gutters on most houses.
The normal EAVES gutters around the perimeter of most roofs - and the gutter that is hidden from a ground-level observer. This is the box gutter.
And while you can neglect eaves gutters (most rural roofs don't even have gutters!), and suffer no ill effects inside the house - box gutters have the ability to destroy a home inside...
And that is why there is a lot more effort put into the design of box gutters. Just to make sure that catastrophic leakage has a very remote chance from happening.
The main problem with all the box gutters that have been installed on Sydney roofs is a matter of perception. Most builders and Sydney roofers do not know about the dangers of box gutters - nor do they know about complex box gutter design that form the basis of The Australian Building Code for box gutters.
The big divide between theory (that also includes regulations and codes) and practice with BOX GUTTERS is caused by a lack of UNDERSTANDING. It is just too HARD to figure out why box gutters have to be so complicated to execute on a building site.
Make things easy and it is easy to apply.
This is my attempt to make box gutter design a little bit simpler to understand. Both for roofers and homeowners.
With this understanding, there will be a lot less problem box gutters around...