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The Refletix radiant barrier that is available here is mylar & aluminum. On normal construction it is stapled in place (make sure to use staples that will last, like monel) (and of course on our weird house, staples and some interesting clips were uses.... there are times when having wood is nice.... like, when you want to attach things...)
Kathy, cutting larger vents or removing the frieze blocks, vs drilling the 'bird holes' vents are fairly similar in time & skill. We enlarges most of our 'bird hole' vents in our ohana. You can buy the larger rectangular vent covers in the same aisle & location as the little 'bird hole' vent covers... the increase in ventilation is well worth it!
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quote:
Originally posted by EightFingers
I'm assuming a ridge vent/soffit vent combo is not do-able in Hawaii?
Killegrew in Kona carriers the soffet vent in rolls. They are about 4" maybe wide.
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[quote]Originally posted by DanielP
Kathy,
If you have 10 ft. ceilings, then it is inside that needs ventilating. The hot air rises by convection to your ceiling, then heats downward radiantly. Install a couple of operable windows (awning style) at the ceiling level to allow that hot air to escape.
I'll make this as clear as I can: what hot air are we talking about that rises by convection? If the air inside is hotter than the ambient temperature (as it is in most homes), you must ask yourself why. People breathing and appliances generate some heat but very little. The air indoors is hot because the radiant heat of the sun comes through the roof, through fiberglass insulation and through anything that is not either sufficiently dense or reflective. That heat, when it hits objects that are dense, like the floor, the walls, the ceiling, the furniture, your head, heats up those objects. Those warm objects then transfer that heat to the air circulating around them. That is why you have hot air near the ceiling in a house.
(A side note: The reason the shade of a tree is cool is because the trees, being filled with water, are sufficiently dense to absorb the radiant heat of the sun and not allow it to pass through and heat up the ground below or you if you are lucky enough to be under one.)
The best solution is to keep out this radiant heat in the first place. Installing a radiant barrier is also the cheapest and easiest solution.
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Kathy, you would only need 3-4 rolls of the Reflectix material, so that would be somewhere around $200. The barrier is fairly easy to install (skinny hubby did much of our low roof area in the WOOD framed (I know, most of you think that that is normal framing, but not at our house!) ohana lying down, some sitting & kneeling was involved. You may be able to find a general handyperson or a construction student at HCC to do this... make sure they use non-corroding staple in the staple gun!
Have you looked at the larger vent covers? Even the long narrow vent would be much better than the 'bird holes' for venting your attic.
And for those that haven't foamed your cross braces at the corrugations of the roof, there are vented closure strips that support the roof at the cross braces.(of course these are not readily available here, limit the venting that the corrugations supply and add a cost to your roofing, more than the side vents cost)
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Kathy,
hotinhawaii is talking about how to reduce the heat coming through the roof. I am talking about letting the heat that is in the attic out. These are both effective and either or both can be used. Just different approaches.
With the ventilation, hot air must be let to escape and cooler air must be allowed to enter. Gable end vents (often undersized and set too low) allow the hot air to escape. With not even bird hole vents and the corrugation sealed up there is no way for the cooler air to enter the attic, therefore the hot air will not escape. It just sits there getting hotter and hotter. You need to create "cool air intake" somewhere into the bottom of the attic. this is usually done with "rafter vents". These go in where the blocks between the rafters are above the top of the wall. Assuming that there are no soffits. Estimated cost for material: $40. Labor: 4 hrs.
Dan
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Technically, Purlins are structural members (usually beams) that are parallel to the ridge of a gable roof. Rafters are structural members (usually 2x6,2x8, etc.) which are perpendicular to the ridge and extend from the ridge to the top of a wall that is parallel with the ridge, and extending to create an overhang or eave . The frieze blocks are between the rafters where they sit atop the wall.
In Hawaii I have often heard the term purlin misused in reference to skip sheeting, the 2x4's atop the rafters which the metal roofing is screwed to.
Are we getting any clearer, or is that just confusing?
Dan
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Where are the bird holes going?
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Ha ha ha! Those are the frieze blocks! The 2x4 between the rafters.
Shaking head.
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"hotinhawaii is talking about how to reduce the heat coming through the roof. I am talking about letting the heat that is in the attic out. These are both effective and either or both can be used. Just different approaches."
This misconception has lingered for too long. Attic vents, no matter how large, will not make nearly the difference in cooling a house that installing a radiant barrier or cool roof will. Not even close!
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quote:
Originally posted by DanielP
In Hawaii I have often heard the term purlin misused in reference to skip sheeting, the 2x4's atop the rafters which the metal roofing is screwed to.
Dan
Skip sheathing (not "sheeting") is a specific type of purlin. Purlin is a more general term for horizontal roof members.
