Decking roof

[Marc]

Thank you guys for so many replies. I have a veranda at home that is all polycarbonate and initially it was tinted and it was sort of cool. The tinting faded away in a couple of years, (had 10 years warranty, yea right) and it is now an oven in summer.
So I think I will alternate one colorbond sheet with one polycarbonate.

I will get 4 of those roof extenders and sit an 8x2 beam to hod up the 6x2 skillion joist...(or are they still called rafters on a skillion roof?)


Yes I must sit them on the wall frame just to be on the safe side as per above picture.
Still the question remains, how much gap should I leave between the (new) rafters and the tiles? How close should I come to the tiles with my new roof sheets?
Just to clarify, my rafters will sit on top of the beam, not hanging like in the above picture, so I will go a bit further and meet the tiles further up, (I need the head-space remember?) Can cut the rafter at an angle and sit a last batten right on the end, and extend the sheets even further so that all timber is protected.

[Barry_White]

Just to clarify, my rafters will sit on top of the beam, not hanging like in the above picture, so I will go a bit further and meet the tiles further up, (I need the head-space remember?) Can cut the rafter at an angle and sit a last batten right on the end, and extend the sheets even further so that all timber is protected.

The size of the gap equals the amount of rain you want blowing in all over the furniture under your decking roof. If you don't think it will blow in ask me about the roofs I've redesigned to overcome the problem.

[Marc]

The size of the gap equals the amount of rain you want blowing in all over the furniture under your decking roof. If you don't think it will blow in ask me about the roofs I've redesigned to overcome the problem.

Yes, I can imagine , perhaps I should have asked, how close to the tiles can i go without it becoming a problem ... thinking in debris clogging up the 'gap' may be? although that wouldn't be any different then stuff in the gutter...since you have done considerable work in this area, tell me if the colorbond sheet will irradiate heat and if there is a practical way to hang some insulation under it.

[Barry_White]

Yes, I can imagine , perhaps I should have asked, how close to the tiles can i go without it becoming a problem ... thinking in debris clogging up the 'gap' may be? although that wouldn't be any different then stuff in the gutter...since you have done considerable work in this area, tell me if the colorbond sheet will irradiate heat and if there is a practical way to hang some insulation under it.

Marc.

I would think that you would need to leave about 50mm to ensure the leaves and rubbish doesn't get caught but bear in mind you are talking about sitting your rafters on top of your beam and this is going to allow wind driven rain to enter between the battens and the beam.

Here is a post that I made last year showing the Solar gain with the various types of materials. You have to click on the picture to see it. There is also a bit of information in the post also.

https://www.woodworkforums.com/showpo...1&postcount=10

With the Spanline Roofing and the Lysaght Flatdek you only need a fall of 25mm to the metre so with a three metre span your roof sheet is only going to fall 75mm so with a 2300 eaves height you are going to have 2225mm under your sheeting at the front of your roof. Also remember using this method you will save on all your cost of the support structure because these roof sheetings will span the three metres without any internal supports.

Why not get a supply only price from Spanline or Lysaght, either of them would design it up for you.