Fade to white: the gradation of the multi-coloured roof

Putting on the roof

Andrew Kerrby author page

4 comments Construction

Wednesday September 30 / Thursday October 8

Falling water

For water supply 60k House will rely on rainwater from the roof to run into the gutters and be collected in a water tank. The length of the roof is nearly 16m meaning there needs to be two downpipes on each side of the building (4 in total). The first job of the morning for Ian the roofer was to set up the brackets to hold the guttering. Unfortunately each length of guttering arrived onsite with a ding in the middle – it had been damaged in transport or when it was loaded or unloaded. We have to wait a couple of weeks for some more. Fear not – we had roof sheeting to put on.

 

Installing the gutter brackets

Installing the gutter brackets

Sunny side up?

Sisalation is a brand name for reflective foil insulation installed beneath the roof sheeting. The sisalation is only installed to the enclosed roof space – not over the verandah. In colder climates (such as Tasmania) the sisalation (sometimes referred to as sarking) is installed shiny side down to reflect the heat back into the building; in warmer climates the shiny side faces up to reflect the heat away from the building. The sisalation comes in a roll and is cut to length before being held in place with foil tacks or staples. The roof sheeting is then installed on top.

 

Sisalation installed under the roof sheeting

Sisalation installed under the roof sheeting

Built for comfort

The roof over the verandah is ‘Laserlite’ (polycarbonate). I selected the colour from the brochure based on a balance between the performance values: light transmission and heat reduction. It was a shock to see the roof sheets onsite – I had thought that ‘Opal’ would be far more translucent. But as the sheets were installed the diffuse light filtered across the building. Later in the day when the sun got hot it was pleasant to shelter in the shade. Installing the lightest shade of grey (Surfmist – nearly white) next to the polycarbonate looked like a good match. My initial surprise and doubt at the colour was dispelled by the results. The moral of this story: always select materials for their quality (thermal performance, durability, appropriateness for the function) instead of for their looks.

 

First sheet of roofing up!

First sheet of roofing up!

 

Ian trimming the sheets of polycarb before installation

Ian trimming the sheets of polycarb before installation

 

By adding an extra purlin near the end span for the polycarb roof sheeting I was able to avoid needing to install safety mesh beneath the roof sheeting.

 

Selected for performance: the 'Opal' colour polycarb provides diffuse light while reducing heat transmission and cuts out UV

Selected for performance: the ‘Opal’ colour polycarb provides diffuse light while reducing heat transmission and cuts out UV

 

The ends of the purlins are taper cut to reduce exposure to the weather. The end grain is also oiled to minimise weathering and water penetration

The ends of the purlins are taper cut to reduce exposure to the weather. The end grain is also oiled to minimise weathering and water penetration

5(0) shades of grey

There are a few big moments in any building project – putting the roof on is one of them. Personally this was the most nervous stage – not because of the task, but because of the appearance.

 

What does a roof need to do? Basically a roof has to keep the weather out (and catch rainwater in this instance). A roof can be a prominent element of a building and define a project – think of the Sydney Opera House. Most roofs, and components including guttering, flashings and ridge capping, are usually the same colour – but they don’t need to be.

 

60k House is about designing for needs (not wants) and to test ideas. I was able to source ‘seconds’ roof sheeting from a mate who works at a roofing manufacturer. This saved about half the price – over $500. I told them I wasn’t that fussed about the exact colours – as long as they were within a designated ‘colour range’. Maybe I wasn’t specific enough – the invoice arrived before the roofing and there were 10 different colours! The only way I could tell from the invoice about the different colours was the roofing screws were colour matched for each of the roof sheets. The night before the roof was due to be installed I spent some time on my computer trying to figure out how to ‘blend’ all of these different colours – I couldn’t. I went to bed anxious…

 

Out in the open: the range of colours supplied, laid out on the grass

Out in the open: the range of colours supplied, laid out on the grass

Truth laid bare

Sometimes it’s best to figure things out on the ground, as you build. This was certainly the case with arranging the roof colours. Once all of the sheets had been laid out it became apparent that some of them just didn’t belong – single sheets and different colours wouldn’t be able to ‘blend in’ or sit comfortably next to the other colours. I know performance is more important than appearance but I still wanted the overall building to look alright. Painting the roof all the one colour was a backup option but something I didn’t want to do if I could avoid it.

 

End of roofing day 1: half of the roof in place

End of roofing day 1: half of the roof in place

 

We only had enough time that day to install half of the roof anyway. I decided to limit the colour palette to five shades of grey and swap the remaining sheets later. I then decided to arrange the colours, or shades, as a gradation – moving from light at the open end of the building to dark at the other, more solid end. The number of roof sheets in each colour was also random but the idea was to arrange the colours in swathes rather than stripes. The end result could have looked like a camouflaged battleship (and maybe some people think that it does) but the general response has been: oh, yeah – that’s alright. At the end of the day (actually after two days, separated by a week of indifferent weather) 60k House had a roof – a multi-coloured roof that keeps the weather out. And that’s the most important thing.

 

This is known as 'weathering' and prevents water being blown up the valley beneath the ridge capping

This is known as ‘weathering’ and prevents water being blown up the valley beneath the ridge capping

 

Good weather for it

 

TIP: Dunlop Volleys are the shoe of choice for roofers – not because of the fashion or affordable price tag but for their non-slip sole.

 

Sense of enclosure: the roof on

Sense of enclosure: the roof on

 

Looking over the roof to the apple orchard and valley beyond

Looking over the roof to the apple orchard and valley beyond

 

Costs: sisalation – $132; Laserlite polycarbonate – $630; Colorbond steel roofing (seconds) – $740; ridge capping – $146; gutter brackets – $112; screws, rivets, delivery, etc – $340; roofer – $1,000

 

Disclaimer: Any advice contained within this blog is of a general nature only and cannot be relied upon. Details provided are in good faith and relate specifically to this project. Any author will not be held responsible for advice or information presented.

4 Comments

  1. I absolutely adore the roof and think it blends beautifully with the outlook over the forest. I think there should be more ‘ombre’ in our sheet metal 🙂

    1. Andrew Kerr

      Thanks for your comment Olivia.
      The decision to accept different colours for the roof and try to blend them into the landscape was one of the more nervous design decisions but am happy with the end result. Glad you like it

  2. You can lay the sheets upside down, the under side color is called ‘wash coat’ very similar to the colorbond color ‘shale grey’ it has the exactly the same paint application prosses in the factory as the top color,

    1. Andrew Kerr

      Thanks for your comment Sasha.
      I had heard the same thing about installing roof sheets ‘upside down’ but prior to installation of the roof I was advised that the underside does not enjoy the same durability. After receiving your comment I posed the question again to the sales representative from whom I sourced the sheets. He referred this onto a product technical representative at Bluescope. The official answer:
      “The backing coat is applied in the same way as the top colour, but is only 10um thick as oppose to 25um on the top coat.
      Backing Coat- a thin coating applied to the reverse surface of the prepainted coil. It also gives additional durability to the reverse surface during the service life of the product, but for aesthetic reasons is not recommended for exposure to sunlight. Performance Requirements are generally not applicable to backing coats. Where specific Performance Requirements are deemed necessary for the reverse surface coating, a “double sided” product should be specified, in which case a topcoat of full nominal thickness will be applied.”
      So yes – you can install the sheets upside down but because the paint thickness is thinner they are not expected to last as long, and the product warranty will likely be void (because it’s not installed to the manufacturer’s specifications).

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