A flyover patio cover is one where the new patio roof goes over the existing gutter on the house and is fixed to a new beam above the existing roof sheets or tiles, (similar to the picture below). The beam is connected to brackets which in turn go through the roof sheets/tiles and are fixed to the rafters and the top of the timber wall plate of the house, this gives a good solid tie down connection, which is desirable when storm season arrives on the Gold Coast and tries to lift your patio roof off.
There are various ways to achieve this connection, you can use a specifically designed adjustable bracket or you can fabricate your own. If you choose to fabricate your own make sure to get some input from a professional. From the new beam above the existing roof, the sheets or panels then go to a beam and posts on the edge of patio area or deck.
The main reason for choosing this method of construction is to get the underside of the roof higher, to give a more comfortable feeling of space or to raise the outside beam higher, you might have a view you don't want to loose from inside the house and in these cases a flyover would be the best option.
Depending how much room there is between the ground/floor and the bottom of the fascia board (the thing the gutter hangs off) you may not have enough height to be comfortable or legal if you use a fascia fixed patio cover, this is one where the patio cover is fixed to the fascia under the gutter Like in the picture below.
When you factor in the fall of the new patio cover (it can be as low as two degrees) over the run of the roof to the outside beam or posts you may find it's too low for comfort or basketballers.
When doing a flyover roof the underside of the roof sheet will generally be 450-600mm above the height of the existing gutter, which means the outside beam will be that much higher than a fascia fixed roof as well, for when you don't want to lose a view for instance.
So if your patio area is 5m from the wall of your house to the outside edge, using a minimum fall of 2 degrees (some products may require more fall) the roof sheet will need to fall 175mm, so wherever the roof sheet starts at the top, after 5m it needs to have fallen 175mm (for every metre of run, it will fall 35mm. ie. 5M x 35mm = 175mm = 2 degrees fall). If your fascia is only 2200mm above the ground level/floor level then it will be too low at the outside beam. There are other factors that may influence your decision as well, how tall are your family and do you have access to the garden walking under the outside beam.
There are a couple of downsides to a flyover and one is that as a result of the roof being higher the weather can penetrate further under, onto your patio area, not only rain but sun as well and two, that when we have the torrential rains that we occasionally have here on the Gold Coast the house gutters will overflow and seeing as they are under the patio roof, they then overflow onto your covered patio area and three, they do cost a little bit more.
So in summary, if you are a family of basketballers or the ground level on the patio is a bit high or you wish to see more of that view from under the patio cover or feel a bit more airflow is required, then a flyover is probably for you, cheers Peter.