There is one and only one good idea for an outdoor patio cover low pitched roof that won’t cost you big bucks in the future – that is to make sure that the unsupported span is no more than 1.2 metres.
However in saying that there are companies that span their product unsupported for very large distances to top that off they also use very thin roof sheeting. The problem with this is it cannot be walked on. You may say you want a patio cover to entertain under not to walk on, well when the patio cover may become a problem and you need a roofer to fix it, it is going to be a real big problem and may be unfixable.
One problem that really stands out is that they bring the patio cover in under the house gutter and weather proof between the gutter and patio cover with polystyrene blocks, this polystyrene does not last that long. Long enough for them to be out of the woods, however then you have a really big problem, it could be leaking profusely you need to repair between the gutter and patio cover. This is not any easy job when you cannot walk on the roof, sometimes almost impossible and can cost you a lot of money.
So a little bit of advice from a roofer with 50 years experience, they may look nice from underneath but a long span patio cover roof could eventually cost you big bucks.
I would suggest that you have battons on support rafters with a kliplok roof deck with a minimum 0.48 base metal thickness that you could jump on. Then I would look at having a weathered flashing from the gutter at least 350mil across the roofing and notched into the ribs of the roofing.
Even better than that if it is at all possible get rid of the gutter, bring the roofing up to the height of the fascia board on the existing house, then have an apron flashing, flashing up under the tiles or colorbond of the house coming across the top of the roof sheeting at least 350mil being notched into the roof sheeting. Then you will have the water from the house roof evacuating over the patio roof. See Blog on this site “Pergola Guttering”.
That means you will never have a problem in that area and if you do you can walk on the roof and can easily fix any problem. I have lost count how many times I have come across these ridiculous structures with problems in that area.
So I say unto you it may look nice but buyer beware – poor choice can be hard to live with, sometimes you don’t get what you pay for.
I hope this information has been useful for you, we like to share our experience of 50 years in the roofing industry.