Week 9: Roof chat

Hello all! Another busy week on the reno, with lots of bits & pieces in preparation for the insulation, sarking, fitting the windows and re-cladding. No massive changes but will put up some piccies below for comparison to previous weeks.

Our deck got roof trusses! After this, the scaffolding has gone back on to allow the roofers access to the deck.

Upstairs has been a big focus this week with lots of work on more demolition and finishing up the framing before the house can be re-clad. You can see the difference between the photos above and below - this space is where the glass stacker door will go.

Internally, the 'cut-out' above the staircase was cut and framed up, and some beams placed to make up for removal of nib walls. More plumbing and electrical work has happened, as it's easier to run everything now than when the outside walls are back on!

This week I have been researching roof materials, namely Colorbond and Zincalume, both products of BlueScope steel. Not only do we want a metal roof, but town planning restrictions dictate that we must have one. So what's the difference between the two products? They are both steel dipped in a zinc-based product to give a protective coating. The main difference is that colour is 'baked' and bonded to the Zincalume to make Colorbond. Both are well suited to harsh Australian conditions, Zincalume may be slightly cheaper than Colorbond depending on the supplier, and there may be restrictions on the use of Zincalume (due to its reflectivity) depending on which council you are under.

Colorbond - available in various colours

Zincalume - silver only

Currently, we have some not so attractive pressed steel tiles in a heritage red colour (see some of the deck photos above). Inside the roof, currently it consists of pressed metal, trusses, battens and the ceiling. No waterproofing and no insulation, so this is our opportunity to get a roofing blanket put in (consisting of a foil-backed insulation) as well as a roof which will hopefully last us 20 years plus.

The question I wanted to answer was - what is better for deflecting heat, Colorbond or Zincalume? Thermal data for the Colorbond colours is relatively easy to find after a quick Google - see link here. Funnily enough, light colours absorb less solar radiation than dark colours, but what surprised me was by what degree. Night Sky for example absorbs 3 times as much solar radiation as Surfmist.

When it comes to Zincalume, this data is surprisingly difficult to find, as it behaves differently to a painted surface due to its reflective nature. The best resource I could find was from Bluescope's Southern Africa website - see pdf link here. This basically sums up that Zincalume performs somewhat like a mid-range Colorbond colour (see last page of the document).

Well that's enough roof chat for today! Thanks for reading, and comments welcomed as usual!