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  1. #1
    Join Date
    Apr 2012
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    60

    Hip Ridge Vent or not

    M hip roof attic, 1200 sq feet, has about 12 feet of ridge; on which I have 10 feet of Shingle Vent II. That's not enough -- the attic hits 135 on sunny days in June (Maryland). And my ductwork is in the attic.

    So I am thinking of installing Hip Ridge Vent (say, 8 feet down each of the four 25 feet long hip ridges).

    The question is whether this would help. There seems to be disagreement about the effectiveness of hip vent (eg; does it undermine the soffit to ridge stack effect?

    Any experience or advice?


    BTW: There is a pre-existing roof fan also that I have shut down, per the advice of "never use both". I wonder if I should just give up on the ridge vent and go with a powered solution. Would rather not.

    BTW2: I have about 85 sq feet of slotted soffit, spread over front and back soffits -- would more soffit ventilation (say, on the sides of the house) help (or hurt?)


    Link to hip ridge vent for those curious: http://www.airvent.com/professional/...hipridge.shtml

  2. #2
    Join Date
    Mar 2006
    Location
    The South
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    2,189
    I believe your thread is better suited to another forum.

    Perhaps roofing.com where experts there could advise you.

    IMO
    Good Luck!

  3. #3
    Join Date
    Jan 2009
    Location
    Keokuk, IA
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    5,520
    I got hte impression that on hip roofs there was a tendency for ridge vents ot short circuti themselves and not work efectively. I think the best solution is conventional vents near the peak and good soffit vents.

    Or, if you have limited or no venting now, you might consider sealign the attic and spray foaming the underside of the roof deck. That's what I eneded up doing on a 1925 home that was already a unvented attic. MY attic only gest to aroudn 80-85F on a sunny day. But it's a more expensive solution.

    More soffit venting never hurts and can help a lot. Just like on a HVAC system you really can't have too much return air.

  4. #4
    Join Date
    Apr 2012
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    60
    Quote Originally Posted by tigerdunes View Post
    I believe your thread is better suited to another forum.

    Perhaps roofing.com where experts there could advise you.

    IMO
    Good Luck!
    Well, this does effect HVAC efficiency (ductwork in attic), and this topic has been discussed in the past on hvac-talk. That said ... thanks for the tip -- I will check out roofing.com.

  5. #5
    Join Date
    Sep 2009
    Location
    Arnold mo
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    3,966
    Quote Originally Posted by danielh View Post
    Well, this does effect HVAC efficiency (ductwork in attic), and this topic has been discussed in the past on hvac-talk. That said ... thanks for the tip -- I will check out roofing.com.
    Another alternative is exterior insulation on the roof, rather than spray foaming beneath it. Having the ductwork in the attic does make the argument for bringing the attic into the conditioned space.
    An answer without a question is meaningless.
    Information without understanding is useless.
    You can lead a horse to water............
    http://www.mohomeenergyaudits.com

  6. #6
    Join Date
    Apr 2012
    Posts
    60
    Quote Originally Posted by tipsrfine View Post
    Another alternative is exterior insulation on the roof, rather than spray foaming beneath it. Having the ductwork in the attic does make the argument for bringing the attic into the conditioned space.
    Ugh, I just spend $3k or so sealing the attic and blowing in 12" of cellulose (not to mention the costs of the soffit and ridge vent). It seems like overkill to foam it.

  7. #7
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,170
    I wouldn't go pav, causes more problems than they solve.

    1 square foot of total net free area per 150 square feet of attic
    is what I've always heard for venting attics.
    this is divided between ridge and soffit.

    the product looks like it would work, basically just
    like ridge vent only for hips.
    it actually it looks pretty nice.

    shingle install would have to be experienced to make
    it come out right imo.

    and if the rain is being whipped around by wind
    you would now have more areas for it to enter.

    I have no experience with this product.
    and only know what I read on their site.

    best of luck.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  8. #8
    Join Date
    Sep 2002
    Location
    Northeast Ohio
    Posts
    4,842
    Power venting will be the most cost effective given the limited design possibilities. I've never found hip venting to be effective.
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  9. #9
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,170
    op do a search of this site for threads on pavs.

    heat rises and will exit at highest point.

    best of luck.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  10. #10
    Join Date
    Apr 2012
    Posts
    60
    Quote Originally Posted by energy_rater_La View Post
    op do a search of this site for threads on pavs.

    heat rises and will exit at highest point.

    best of luck.
    It appears I have several uncertain choices: go PAV and seal up the current ridge vent, or install hip ridge vents, or power intake, or just live with it. I don't think I could get a clear "majority vote" on any of them!

  11. #11
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,170
    the problem with pav's is that they draw conditioned air
    through leaks in ductwork, equipement & plenum connections
    and conditioned space below.

    140 degree attics are common. its just the time of year.

    rather than put pav's putting a passive turbine is another
    option.
    have you determined your ventilation needs with the forumla
    I posted?

    what type of air sealing for 3K did you do in the attic?

    best of luck.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  12. #12
    Join Date
    Sep 2002
    Location
    Northeast Ohio
    Posts
    4,842
    PAVs would cause problems with improperly sealed attic ducts if soffit vents were inadaquate, not so much if they are. cfm air in = cfm air out = no negative pressure = lower attic temps = less duct loss.
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  13. #13
    Join Date
    Sep 2009
    Location
    Arnold mo
    Posts
    3,966
    There was an HVAC pro on this site who once mentioned he has been air sealing and then spray foaming the duct systems in attic. The R-value needed would be climate specific, but the concept seems sound in theory. Another approach I've heard of is to encase the ductwork in drywall and then air seal & insulate that to bring the ductwork into the conditioned area. I believe a 1/2" of drywall alone between the ducts and the conditioned area did not create any condensation issues because the 1/2" of drywall has no big r-value. Obviously I have not done a lot of research on these ideas, but thought I'd throw them out here for thought.
    Getting the duct system better insulated would pretty much do away with any need to address better attic ventilation.
    An answer without a question is meaningless.
    Information without understanding is useless.
    You can lead a horse to water............
    http://www.mohomeenergyaudits.com

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