roof vent installation on private house

[MrJ]

Hi all,

 

considering to install roof installation on my single story house in order to cool down the temperature mostly during day time - saw some of this shining self spinning vents on top of the roof (about 3.800 THB incl. installation)

 

Any experience about the benefits of such system? how many such vents i Would need (may 2 on top of lr with 45sqm and 1 on top of mbr with 20sqm?), are there additional indoor vents necessary to help to get warm air to the roof? additional insulation recommended - though don't wan to spend 200k for the foam spray.

 

At the moment i Have about identical temperature in and outside of the house during daytime - I would be happy to be able to reduce the inside by about 2 degrees.

 

Thanks for your input.

[r136dg]

I recently installed a whirlybird fan in my roof. B3,500 for the fan/vent & B2,000 for installation (new construction so didn't op for the install part). They're big & some might say they're horrific looking (not that I care). We had a section of roof to install it in that can't be seen. It's always spinning, even when there doesn't seem to be any breeze. I'm glad I put it in but can't give you solid results since our attic isn't sealed up yet. I can tell you of a friends (very smart man) knowledge on the subject. He has temp sensors in his attic & installed 2 or 3 whirlybirds & said attic temps went down a bit with each install.

If you have the standard cement tile roof it's vented all the way around at the bottom of the first course and those tiles are far from air tight. Otherwise I would have vented our eves. 

I don't know about the whole insulation argument. I would think it could slow heats entrance but retain the heat once it's in there.

Will not pertain to you but I think the biggest impact on keeping attic temps down for us will be the tiles we chose. The lightest color SCG's.

 

[MrJ]

thanks - any idea about additional went/whole in interior  ceilings?

[eyecatcher]

 You can buy the standard ceiling extract fans at any store, but rather than vent them into the roof void, just spend a tad more and flexiduct them to the outside. you can do this via a gable wall or even an eaves soffit.

 

As an alternative to the whirlygig you can use ridge vents. These are a proprietory ridge tile component which you build along the roof line and you could set them up one every metre or in tranches of 1m lengths.

Best place to look at these wold be SCG building solutions, they tend to push western building products for the more astute customers.

 

Loft insulation I have noticed here is pretty poor generally available in 2" or 3" thick, pathetic at best. The R values  are marginally better than laying some old cardboard boxes in the roof.

 

However I have found a 6" insualtion sold at Home pro recently. Suncool extra cool  its R37 so as expected a lot better than any other product. Only 359bt reduced from 590bt for a 4m roll. Its foil wrapped so safe enough to lay .

 

I have built another roof on top of my roof (Thai style) and left most of my 8m ridge completely open. so its open from the top row of tiles each side, about 300mm. with a secondary roof over the top it also acts as an insulative barrier and of course hot air build up can dissipate up and out.

to expediate this though,the general accepted principle would be to have eaves soffit vents and gable vents to facilitate cross flow.

 

If you can incorporate everything above into your roof, its certainly gonna be a cooler roof but it doesnt stop heat coming in via walls and windows.