Should I block suicide and gable vents in garage?

Discussion in 'General Home Improvement Discussion' started by fastsvo, Jun 18, 2018.

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  1. Jun 18, 2018 #1

    fastsvo

    fastsvo

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    I am in the middle of insulating/air sealing and my garage including drywall as well. The attic space will have it's own O'hagin intake vents and a solar fan for exhaust.

    Climate = sunny and dry (LA), yet will remain an unconditioned space.
    Utilities = Two gas appliances (water heater and HVAC), each have their own vent pipe to the roof.
    Purpose = Will remain a garage where I will store cars and use for hobbies.

    The home was built in the 60's and has two foundation, aka suicide vents on the bottom and a single gable vent up top (below the new ceiling).

    My original plan was to seal these three vents, in order to keep the heat/cold out. Kinda pointless to insulate the garage if I keep these vents open.

    I understand that these might no longer be required by LADBS but now the garage is air sealed and "tight", would it still be in my best interest to close these up? Perhaps just leave the gable vent open? What about the fresh air needed for the gas appliances?

    Sorry for all the questions, but need to make a fast decision as we are currently in the midst of this renovation.
     

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  2. Jun 18, 2018 #2

    nealtw

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    What will you be doing with the ceiling?
    Yes you want fire air for the appliances, Does the furnace feed the house or just the garage,?
     
  3. Jun 18, 2018 #3

    fastsvo

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    The ceiling will be closed up with drywall and insulation. And yes the HVAC supplies house but not the garage
     
  4. Jun 18, 2018 #4

    fastsvo

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    I was hoping to get away with blocking the foundation vents and keeping on the Gable in order to keep the dust to a minimum inside the garage.
     
  5. Jun 18, 2018 #5

    Snoonyb

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    !. Under floor access in raised foundation construction, in S. CA., is accomplished in two methods, Either in the floor of a closet, or by 1 or more 18"sq. screened access portals.

    If they are blocked and you have a sub floor plumbing or electrical problem, IT WILL BE EXPENSIVE.

    Houses built on a slab foundation are not required to have under floor access.

    2. Your fuel gas appliances, If installed, permitted and inspected, met the required combustion air requirements by virtue of the existing ventilation in the garage at the time of the install.

    You altering that then requires you to provide those requirements, by another method, and I'd strongly advise you to obtain a permit.

    The gable vent, in conjunction with the eve vents, provide ventilation for attic spaces at the rate of 1/150.
     
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  6. Jun 18, 2018 #6

    fastsvo

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  7. Jun 18, 2018 #7

    Snoonyb

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    Those are just "dress-up".

    Both your overhead and any pedestrian door will leak air.

    You can run dedicated ducting, individually, for both appliances, too provide combustion air.
     
  8. Jun 18, 2018 #8

    fastsvo

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    Yes they are. I can't imagine it restricting flow over the current open net design and perhaps it will keep out some of the crap from coming in.
     
  9. Jun 18, 2018 #9

    nealtw

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    The furnace and water tank should be in a closet with an exterior door that would prevent auto off gasses from getting to the house and gasoline fumes from getting into the fire in either.
    Fire air can be a 6" round vent and if you are worried about dust near the ground move it up on the wall.
    The attic should have soffit vents and air chutes to let air into the attic and box vent or ridge vents at or near the peak and the gable vents can be closed.
     
  10. Jun 19, 2018 #10

    Snoonyb

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    They have a finer screen mesh then the existing foundation vents, usually fiberglass and will require vacuuming over time.
     
  11. Jun 19, 2018 #11

    maxdad118

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    Get a cheap furnace filter and cut it to fit the vent openings around the garage. That will keep dust out. Cut it a little big to wedge it in there. Your appliances have plenty of combustion and ventilation air without them. Make sure they both are drafting well when in operation. Most furnaces have inducer motors for pushing exhausts out the flue.
     
  12. Jun 19, 2018 #12

    Snoonyb

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    And change and/or clean them, how often?
     
  13. Jun 19, 2018 #13

    fastsvo

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    My furnace does indeed have the inducer motor for the exhaust but nothing for the water heater. Wouldn't the filter cut down on the existing air flow coming in from those foundation vents?
     
  14. Jun 20, 2018 #14

    maxdad118

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    I thought you wanted to keep dust out? If it was me, I’d sheet rock over them.
     
  15. Jun 20, 2018 #15

    fastsvo

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  16. Jun 20, 2018 #16

    maxdad118

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    If you aren’t parking a car in there, not keeping any flammables(solvents, gasoline, etc) and gas appliances are venting there shouldn’t be an issue. Gas appliances are inside homes all the time in CA. In confined closets, yes, they have CVA openings BUT it’s mainly to provide combustion air! The garage has PLENTY of air for a water heater and FAF. Put a CO detector in the garage and soap check your gas fittings. I do this for a living. I, personally, would not be worried doing it if you are smart about things.
     
  17. Jun 20, 2018 #17

    Snoonyb

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    Read post #1, or for that matter the whole thred.
     
  18. Jun 20, 2018 #18

    fastsvo

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    I am going to store a car in there and use it as a general garage instead of a living space. Of course looking around the garage I do agree it seems to have a lot of air to be used for combustion. One item I haven't been able to scientifically nail down is given my use of the garage and the way it's being built out right now could I potentially block the lower foundation vents yet keep the existing single gable vent? The only reason I bring this up is that it might serve as a good happy medium?
     
  19. Jun 20, 2018 #19

    Snoonyb

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    Gable vents are generally an exhaust Item and for each exhaust/exit you need and intake/supply.

    If you are finishing the ceiling, only eve vents, those above the ceiling line are the intake/supply.

    As mentioned before, your pedestrian and overhead doors will leak, however they, because they can effectively gasketed, are not considered in the combustion air calculation, only the foundation vents and/or dedicated combustion air ducting.
     
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  20. Jun 20, 2018 #20

    nealtw

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