Roofing

One of the earlier design principles was that the walls should be protected from the sun as much as possible through generous eaves.  This is possible through 2 steps

1. A steep pitch of roof allowing a deeper drop of the eaves
2. The roof covering ALL sides of the house.  There are quite a few houses where 2 sides are exposed to the sun. 

The 1st pic (Sketchup) shows a conventional roof in many houses.   The shadows shows much of the ground floor wall exposed.

The 2nd pic shows the improved design (now more common) with a roof covering on all 4 sides.  You can see now that part of the side of the ground floor is sheltered.


Another important design requirement was ventilation.  This meant the addition of gables and/or dormers on the roof with louvered windows for constant circulation of air.

Hence the best roof design (from my perspective) is in the 3rd pic (without a dormer-too much a hassle to draw lah).

The little window allows for constant ventilation.  A ventilator fan is even better.  Look at this product - Solar Powered Gable Mounted Attic Fan

Finally there remains to determine the material for the roof.  It appears that there are no totally satisfactory solution.  Tiles will eventually deteriorate and it has been found to be leaky as well.  Spandek (zincalume) metal roofing is ok until the rubber ring around the nails deteriorate and water leaks in.  In addition it requires more insulation due to transfer of heat.  In the end we decided on Kliplok where no puncture of the roof is required and hence waterproofing is better.  They have a patented system of clipping the roofing under the overlapping roof sheets without puncturing the metal.  It was emphasised on us that metal truss would be required to minimise warping of the roofing (and leaking).  I am not sure why.