I am trying to find out about installing a whirlybird onto a decramastic roof.
This sort of roof is a pressed metal sheet that looks like a tile but is made of sheets about the size of four tiles.
It is then sprayed over the top with some sort of rubber and glue.
The instructions say put it under the top beam of metal, but it is stuck down with the rubber and glue so I suppose you just cut it and slide it under?
Installing a Whirlybird onto a decramastic roof?
(7 posts) (6 voices)-
mvstorey
MemberPosted Wednesday 30 Nov 2011 @ 8:09:53 am from IP # -
cool at home
MemberI can't answer your technical question about the roof, but I wouldn't suggest installing a Whirlybird anywhere... and I've done it myself, so speak from bitter experience. They are not effective unless you have an awful lot of them, and then they are not so cheap. The volume of air one (or 2) moves - particularly on a still day - is relatively low and won't be enough to address the rate of heat build up in the air that is replacing it. While you sometimes hear of people who have found their WBs 'great', in most instances this is because their insulation is insufficient, and money would have been better spent on that. There's a lot of scientific information around... easy enough to Google, or even search these forums.
There are also issues about when in the day attic air should be vented and replaced - I'd say overnight, not during the daytime unless you have a significantly cooler air source consistently available to replace it during the day.
Motorised vents are far more likely to give you the relief from heat that you are wanting... unless of course your reason for installing the Whirlybird is moisture venting, when I take back everything I've just said.
Posted Thursday 1 Dec 2011 @ 2:56:03 am from IP # -
Lance
Key MasterI second that, whirlybirds are just not effective at cooling a roof cavity, use either a mains powered fan vent or a solar powered one, forced air cooling is the only way. Remember, to keep ahead of the heat you have to change all the air in the roof every 5-10 mins!
Posted Thursday 1 Dec 2011 @ 4:03:08 am from IP # -
fireflies
MemberI think the best - only? use for the oft mentioned seldom used low scale earth-tubes would be ceiling ventilation where air temperature alone is of importance rather than air quality which has to take into consideration fungal spores, humidity etc.
Posted Saturday 3 Dec 2011 @ 12:21:50 am from IP # -
mvstorey
MemberWell thanks for all your advice it is great to get some objective and experienced input into a problem.
I really like the idea of the earth tube air as I too was wondering about the quality of that sort of air.
Can you provide me with any technical data or link to find out about them?
I have an area near my roof that I was thinking of buring in about 1-2m of fill and leveling out. I was going to put some tubes under the ground and collect the cool air from it, but was not sure how much length would be effective or the size of the pipe.It may be worth doing to put the air into the roof cavity and then install the wirly bird?
Yes I do understand the limitations of wirlybirds, but I did find it effective in a previous house to remove the heat enough to justify the expense and effort, at least it seemed to be effective as I did not do any proper measurements of temperature before and after. It did have effective insulation, as does my present home.
It appeared to cut the average temp by about 5 degrees in the house, or perhas it just made me feel better that I had done something? Installing it was a pain (knuckles) but that is another story!
Posted Saturday 3 Dec 2011 @ 7:03:17 pm from IP # -
jimbo22
MemberYep whirly birds don't seem to be effective enough for what they're made to do. I think the price point being low is the main reason people find themselves purchasing them.
As I pointed out on a few other posts - http://www.roofventilationblog.com.au/roof-ventilation-alternatives-chart/207/
So you can make your own decision
Posted Wednesday 12 Feb 2014 @ 11:09:27 pm from IP #
