A friend wanted to do repairs to his house and thought that since he was going to suffer the dust, he might as well make some extensions and additions to provide for his increasing needs. So, he asked if what he was going to do was ok.
There were no plans at that time apart from knowing that it will end up as an L-shaped on plan. The best shape feng shui ask for is a regular rectangular shape with all four corners intact. Empty corners at acceptable areas are still ok but minimize the oddity of the L-shape. That is, do not make it too pronounced.
His house sits in a general southwest-northeast orientation so the first suggestion would be to avoid having an empty corner at the north. Viewed from outside the front gates, the right corner of his house cannot have a recess. That means he cannot design a recess garage or porch or open store for his knick knacks and such there as it would weaken the potential vitality of his house. In fact, it would be harmful.
For the other eight directions, this simple sketch may be of help.
This book is a translation of a text by FengShui Master Jiang Da Hong (ca1640) with my explanations and comments. The root text is a section on yang dwellings from his book “5 Songs of the Heavenly Principles”.