Colourbond Roofs- Placement of Whirlybirds - Cosmetic considerations

Greetings

I was wondering what peoples opinions were on where whirlybirds should be positioned. I understand they must be as high as possible near the ridge capping to vent all possible air. (Halfway down may still result in the ridges corroding ??)

But cosmetically where would you place them?
I assume on the back (non street facing) sections of your roof? so as to only see a nice flat expanse of sheeting and valleys from the street.

Do any homeowners or roofing tradies have opinions on what theyve done or would do?

Cheers
Dale

Hi Dale

I know from experience that halfway down the roof on the side sheltered from the prevailing wind doesn't work (rarely spins). I would place them on the back of the house for purely cosmetic reasons. I would also place them sufficiently high that they just show above the ridge.

From recollection there is some guidance that comes with the product in the installation directions.

I think that the direction of the wind could be a significant factor.

Fred.

Dale

As Fred says they need to be as near to the ridge as possible to catch the wind. They certainly need eaves vents to work efficiently.

They can be bought in all the colorbond colours to match the roof and in the end who looks up at a roof and says "Those ventilators look terrible on the roof" Just doesn't happen and they would add to the value of the house because it would be one more thing that people wouldn't have to buy if the house was for sale.

Don't understand your comment about the ridge corroding.

If you do a search on the forum whirly birds have been discussed pretty extensively.

If you are using more than 1, I would put them on alternating sides of the ridge cap.

Hi Dale,

I always put the whirly bird up the top of the roof and slide the flashing under the ridge capping. That reduces the risk of it leeking in the future plus the whirly bird works at its full potential as it isnt blocked by any wind disturbance.

Thanks...Mark

I put multiple 'birds in. They don't need any breeze to work, they just use convection to remove heat from the roof cavity. They do work better if you have a cavity in the wall (like a double bricked house) as they suck they warm air up past the walls and drag cool air into the cavity. I have them at the rear of the house near the ridge capping.

Note though, that you need to be able to stop them in winter, you actually dont want any air movement in your walls or roof over winter.

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Originally Posted by namtrak

Note though, that you need to be able to stop them in winter, you actually dont want any air movement in your walls or roof over winter.

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Had a neighbour who used to put a plastic bag over his - got any better ideas?

Scooter,

You can buy caps for them. You unscrew the whirlybird and replace it with a metal cap which seals the hole. Can be a problem however if you have a few whirlybirds as they have to be marked well to make sure that the right ones goes back on the right hole.

Hi there

Thanks for the suggestions, I believe right near the ridgeline but on the non street side is the best combination cosmetically and functionally.

However what about using these ridgecap vents which of course are less obtrusive and I assume it would be possible to place them along nearly all of the ridge lines if you wanted to? Does anyone know of any data that proves which system is more effective?

I suppose that it's a matter of taste, but I'd rather look at a whirlybird than have that thing on my ridge.

Roll cap looks nice, and even nicer when it's pop riveted instead of screwed down with those big obtrusive roofing screws.

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Originally Posted by pawnhead

...............Roll cap looks nice, and even nicer when it's pop riveted instead of screwed down with those big obtrusive roofing screws.

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Have to screw them down if you're in a cyclonic area, and you have to use screws with 3/8" heads, not 5/16" or even smaller as is often used down south.

Mick

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Originally Posted by pawnhead

I suppose that it's a matter of taste, but I'd rather look at a whirlybird than have that thing on my ridge.

Roll cap looks nice, and even nicer when it's pop riveted instead of screwed down with those big obtrusive roofing screws.

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At the end of the day who looks up at a roof and says "Those screws look terrible why didn't they use a nice pop rivet"

I think you would find that when standing on the ground looking up at the screws and they were colour matched you wouldn't even notice them and that would be deviating from good building practice.

As Mick says it is a requirement in cyclonic areas in fact I think pop rivets would be challenged by any council inspector.

One of the areas looked at after Cyclone Tracey was the most susceptible areas on a roof during high winds was the cappings and flashings. This was the first area to go on a roof because of inadequate fixing, this then opened the roof up to the ingress of wind and the rest of the roof followed the flashing and cappings blowing into the neighbours back yard.

When you look at AS1170 on Wind Forces the highest pressures on a roof in high winds is at the ridge and the edges so this is where your best fixing should be.

Don't know how it's done elsewhere, but up here the screws that hold down the ridgecap go down through the top of the roofing sheet and into the top batten. They're a tie down requirement, usually 12 gauge type 17 screws, 50mm long for custom orb, 65mm for trimdek.

Mick

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Originally Posted by journeyman Mick

Don't know how it's done elsewhere, but up here the screws that hold down the ridgecap go down through the top of the roofing sheet and into the top batten. They're a tie down requirement, usually 12 gauge type 17 screws, 50mm long for custom orb, 65mm for trimdek.

Mick

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12 gauge are standard everywhere but from my experience with Lysaght was that 14 gauge were required in cyclone areas.

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Originally Posted by Barry_White

At the end of the day who looks up at a roof and says "Those screws look terrible why didn't they use a nice pop rivet"

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I do. :D

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Originally Posted by Barry_White

As Mick says it is a requirement in cyclonic areas in fact I think pop rivets would be challenged by any council inspector.

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Well I haven't built anything north of the border, and I haven't been picked up for not installing cyclone bolts here in Sydney either.
A roofing mob that used to do our metal roofing always used pop rivets on capping and all the jobs passed inspection, and they looked good to me. I don't know if he was being dodgy or not, but he did it for the looks, not for time or money saved.
As to whether they're required by the code or not, I couldn't say. As for good building practice, you could put your screws in every orb of every batten and that would be excellent building practice as far as cyclones go. Just depends on how much work and money you want to spend I suppose.