Which roofing solution to use for coolest house?

Hi all,

Hoping to get your advice on the best roofing solution to use please, to cool our house down.

We currently have an old corrugated iron roof, rusting in parts, which heats up like an oven in summer and cooks everyone and everything inside the house

What would be the best solution to make the house cooler in the warmer months? I have looked into reflective paint, ducts in the space just below the roof and/or replacing the whole roof with a new one (with different material?). I am now slightly confused by the options available and am hoping that some of you have had experience in this area and can shed some light?

Cost is not an issue if it means the house will be cooler (although would prefer to work with the existing roof rather than replacing it).

Thanks for your help!

Virginia.

Reflective foil laminate - RFL e.g. Sisalation under the roof will block out >99% of radiant heat transfer. It can reduce AC requirements by up to 20%.

I've noticed a few sustainable houses using colorbond. Also the marketing material claims the newer versions are more reflective than the old ones.

Although its hard to tell if its true or not

1. Light coloured paint on the outside of the roof.
2. Sisilation under the iron
3. Insulation batts on top of the ceiling (R 3.5)
4. Whirly bird roof ventilators installed
5. Vents on all sides of the house under the eaves.
6. Plant trees to shade the house from the west and northerly sun

Both our neighbours and ourselves have colourbond rooves with ceiling batts. Theirs is a dark colour, whereas we used Surfmist-the difference between the two houses temperature wise last Summer was significant! They had to use their A/C most days over 30c, whereas we ran ours for less than 2 hours for the entire Summer!

A lot of people do not realise how much hotter a house gets by using a dark coloured roof, your example given shows that point clearly. I had to remove some iron from a roof for access once for a client and the house had 2 different colours on the roof (Half way through re - roofing and they ran out of money, hence the 2 colours)
Whilst up their working under the lighter colour it was hot, but very bearable. When we had to move to the old dark side it was like walking under a furnace, VERY HOT.

I always shake my head when I drive past housing estates and look at the sea of BLACK roof's. They do not realise how much more energy they have to use to cool their house's. If I bought a house that ticked all the box's, and the roof was black I would replace it immediately, even if it was only just put on. A black roof could cost you tens of thousands of $$$ over the life of the home in extra power.

Interesting
I could not pull off a surfmist roof due to the darker brick colour, however I found this on the colorbond website:
http://www.colorbondcolours.com/index.c ... CA970272AA

I'm currently planning to have a Windspray coloured roof which is a medium, so its going to absorb some heat but not as much as darker colours....
I did notice most of my neighbours have chosen red bricks & dark blue or very dark colours for their roof, I wonder if that will mean their house will be hotter in summer...

Do you both have the R3.5 insulation in the roof? As that would also change the results

^^^Yes we do.

Re roof. If its rusting then its time to upgrade/repair. New color bond roof with sisilation and insulation in ceiling will make a big difference. It will be pretty costly though. any other fix/repair will just be wasting money though.



As mentioned above:

-Colorbond roofing
-Sisilation (foil) under the roofing sheets
-Batts or blow in on top of the plaster ceiling (blow in is cheaper and rates higher than its specified value)
-Vents through the roof as close to the peak of the roof. placement is key. Remember that heat rises so it rises to the peak. Color bond also conducts heats (as its metal) more that cement tiles. Get the heat out as quickly as possible by using variable speed powered vents (solar)
- Light colors if possible. If you have a raw (gal/zinc) color then you can probably get away with a lighter color and this will help.

If you want to really go the whole hog. Look at a whole house fan. Basically a massive fan that operates at low speed and draws air through the house. Open your windows and run the fan. It will draw the air from outside through the window through vents in the ceiling then out the roof. Also great for improving circulating air flow and getting fresh air in the home.



If its rusting, then its time to replace.

From personal experience in the same suburb,

House one has 9 ft. ceilings wool blown in insulation and blue colour bond roof with whirly birds

House two has 8 ft. ceilings no insulation, black concrete tiles and no whirly birds

House one is a lot hotter during the day, very noticeable difference it is very hot but after sunset it cools down very quickly

House two retains the heat into the night you can feel it coming from the roof however I do think this could be reduced with some insulation of some sort, batts, whirly birds etc.

So to summary choose when you want to be hot, apparently terracotta tiles is the best of both worlds which I have to agree as I live in a house that has them with no insulation but the cost now days of terracotta

ok here the same answer that i used for an earlier post

http://www.solarspan.com.au/solarspan/

disclaimer is I only know what i have read and have never roofed however i have my first build coming up and am doing the research.....

anybody know costs?? say of a traditional colorbond(+ sarking + ????) VS Solarspan????

regards

These experiments people have done are not very scientific. There are so many other variables here its not funny.

Interesting note: I was at another house the other day. I thought wow this house is so cool unbelievable. I took note of the brivis thermostat it read 22 degrees. I went to my house which I thought was hotter and to my surprise it had 21 degrees.

The other house maybe felt cooler because there wasn't as much natural light coming through.

And how much they save in winter.

We seem to get plenty of winter sun nowadays and the central heater isn't on at all after it is used first thing in the morning to warm the house up.

Last summer we used our split system a/c only a handful of times (we only had one 40 deg day) but as for that extremely hot summer 3 years ago, EVERYONE was using their split systems, black roof or not.

^^^Eager, our last two houses have had black rooves ( this one is Surfmist-so white) and this house is by far the warmest we have had in the winter-because we planned for the windows to catch as much of the low winter sun from sunrise to sunset as possible (passive solar). In the Summer when the sun's arc is higher is doesn't hit the glass as much but belts down on the roof instead-ergo the lighter roof works better then.

I guess it comes down to where in oz you live. PPL in Tas may want a warmer house where up in darwin it needs to be cooler. I just figure with a planet that is getting warmer each year it's better to have a cooler house.

Here is a link to a government paper after research into insulation effectiveness and total r-values of different roof/ceiling/insulation scenarios.
They don't cover light vs dark coloured roofs but you can probably dig those figures up somewhere. Maybe the Colorond site ?
From there all you have to do is weigh up the cost to benefit ratio
http://www.google.com.au/url?q=http://w ... cdOiDppd6w

Stewie