gable vent ...AND ridge vent?

landngarageNovember 6, 2012

My new construction, brick, galvalume roof, story and a half home, has three gable ends. Ridge vents will run along the roof, with perforated hardy board soffets. We have three standard vinyl round gable vents ready to install also. My builder suggests that we use them as purely decorative (no hole to make them functional).

I live on the gulf coast, hurricane country,...one friend said gable vents can let in water during heavy winds. But these vents are new and hopefully engineered to stop wind driven rain,....I'd like some extra ventilation.... thoughts?

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Beth Parsons

I'd love to see answers/opinions on this, too. Our plan calls for 4 vents on either side of the roof but with ridge vents, 2 powered roof vents and a huge attic I wonder if we can save the $$...

    Bookmark   November 6, 2012 at 9:09AM
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Sophie Wheeler

Ridge vents work in conjunction with eave vents. Doing anything else is counter productive for roof ventilation. No gable vents. No power vents. The aire flow is from the unobstructed eaves (with insulation chutes to maintain clearance) through the underside of the roof and out the ridge.

However, in warm climates, having a sealed attic with zero venting would be the best choice for the home. Especially if you have ducting planned for the attics.

    Bookmark   November 6, 2012 at 9:44AM
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landngarage

I think we are past having a "sealed attic" at this point. And this being a story and a half, the "attic" is a rather small area at the very peak of the roof. Roof trusses are 2x8's... the cross ties that define the small attic are 2x8's also. We will have insulation chutes/spacers between the roof and the fiberglass. A silver galvalume roof will be used.

    Bookmark   November 6, 2012 at 9:55AM
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energy_rater_la

baffles in rafter bays dedicate pathways for
cooler air to enter soffit ventilation areas.

why builders mix ventilation strategies in
attics, I'll never know or understand.

there are three methods of venting
attics, each are stand alone methods.
not mix and match.

gable end venting.

soffit and ridge venting

soffit and passive vents

some areas are outlawing pav's, with good
reason. Georgia is the latest to do so..see
article below.
as pav's pull hot air out of attic, they also
pull cool air from duct leaks & from holes in
floor of attic from conditioned space below.
do they cool off the attic..you bet ya. by
robbing conditioned air that you pay to cool.

pav's..never a good idea for the person who lives
in the house & pays the bills.

undoubtably unvented attics benefit hurricane areas
more thatn vented attics. putting insulation on the
roofline puts ducts & equipment in semiconditioned
space, and minimizes problems caused by holes in
air barrier at attic floor.

but for those who don't go that route, proper attic
ventilation is important. just as important is sealing
holes in attic floor. ICAT recessed cans, sealed supply
boxes that penetrate attic floor, sealing oversized
cuts at bath vent fans and so on.
insulation doesn't work when air moves through it.
creating an air tight barrier between attic and living
space is crucial.

Georgia Pulls the Attic-Ventilator Plug
"The state residential code allows only solar-powered versions; plug-in powered attic ventilators will no longer be allowed
Posted on Aug 31 2011 by Richard Defendorf

Building science target. The money that would have been spent purchasing and installing one of these attic fans could pay for a more cost-effective upgrade, which would include more ceiling insulation and proper air sealing.
Attic ventilator fans have taken a whupping in the court of building science, played starring roles on useless-products lists, and gotten roughed up in the comments sections of blogs. Now they�re gadget non grata in Georgia�s supplement to the 2009 International Energy Conservation Code.
Actually, as energy consultant and Energy Vanguard blogger Allison Bailes points out, that particular part of Georgia's code supplement contains a loophole. In its list of mandatory "Systems" requirements, Georgia allows solar-powered attic ventilators, but attic ventilators designed to use grid power "shall not be connected to the electric grid." In other words, you can have one, as long as it's not plugged in.
Dealing with the heat
Despite the compromise, the rap on attic ventilators is now anchored in code. Promoters of these machines say the devices help cool attics by exhausting hot air to the outside. However, attic-fan critics say the fans often draw makeup air from a home's interior. During the summer, there's obviously a major energy penalty if your attic fan is pulling air-conditioned indoor air from the living space into the attic through leaks in the ceiling.
Frequently cited research results from a study conducted in 1993 and one conducted by the Florida Solar Energy Center show that attic exhaust fans also can depressurize the living area to the extent they create potentially hazardous backdrafting conditions, particularly in homes with atmospherically vented gas appliances.
Energy consultants like Bailes and building scientists from FSEC and the Building Science Corporation suggest that, for most homes, the most cost-effective and safe approach to address high heat in attics is to perform air-sealing work at the ceiling and to insulate deeply. "

best of luck.

    Bookmark   November 6, 2012 at 11:49AM
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landngarage

I have called my builder. The gable vents will be installed as decorations only. I will redouble my caulking and insulation efforts between my little attic and the AC'd living space. Thank you!

    Bookmark   November 6, 2012 at 12:10PM
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athensmomof3

Ha. Just built in Georgia with power vents. Passed code. Not solar power. I understand the thought process behind no power vents (but didn't read them until after they were installed and we moved in). However, we moved in in late July. Our upstairs heat pump never kept up. Went on for several months and was troubleshooted (or troubleshot;)). I was in the attic and noticed the roof vents were never hooked up to electricity. They were hooked up, a/c immediately cooled and worked much less, bill went down 350.00.

Wonder why? Temperatures were consistent. We do have quite a bit of attic insulation but only blown in cellulose (a lot of it though). Perhaps that sealed any holes where air could be sucked in.

It was not the result I was expecting but am very glad for it.

    Bookmark   November 7, 2012 at 11:55AM
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energy_rater_la

atricle is recent. would not have been in effect
in july.

good for you landngarage.
make sure that a/c supply boxes are sealed to sheetrock
ceilings, oversized cuts at bath fans are sealed
and recessed lights are ICAT and not just IC.

best of luck.

    Bookmark   November 7, 2012 at 1:33PM
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