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  1. #1
    Join Date
    Nov 2011
    Location
    Sedona, Arizona
    Posts
    20

    Default House HVAC system also supplies workshop off garage?

    HI,

    I know that the house HVAC system cannot have supply or return registers inside the garage but what about a workshop that opens to the garage?

    I do not like the set up I saw at the last inspection yesterday, where this workshop had supply registers and a return duct from the house system, even though there was a self closing fire rated door between the workshop and the garage, and fire rated walls.

    What if someone is using solvents, flammable paints fumes or noxious glue fumes in the workshop? These fumes would enter the circulating system of the home. I will caution the buyer about this hazard and recommend that they consider disconnecting this section of the HVAC system.

    Does anybody know if there is any specif prohibition in the codes for this situation?

    Thanks
    JP

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  2. #2
    Join Date
    Mar 2007
    Location
    Fletcher, NC
    Posts
    28,032

    Default Re: House HVAC system also supplies workshop off garage?

    Quote Originally Posted by JP Lomeo View Post
    I know that the house HVAC system cannot have supply or return registers inside the garage but what about a workshop that opens to the garage?

    I do not like the set up I saw at the last inspection yesterday, where this workshop had supply registers and a return duct from the house system, even though there was a self closing fire rated door between the workshop and the garage, and fire rated walls.

    What if someone is using solvents, flammable paints fumes or noxious glue fumes in the workshop? These fumes would enter the circulating system of the home. I will caution the buyer about this hazard and recommend that they consider disconnecting this section of the HVAC system.
    First, are you sure those were "fire rated walls" and the door was a "fire rated door' - those words should not be used unless you know those items are "fire rated" as those words indicate a specific thing.

    "Separation" is all that is required between a garage and a dwelling, and those "separation" walls and doors are NOT "fire rated" (unless someone actually chooses to use the code option of a 20-minute fire resistance rated door (few elect that option as it costs more).

    Back to the essence of your question:

    1) A clearer description to make sure the scenario is received properly - there i, or is not, a door between the house and the "workshop" (a door is not required there, but common sense says you would want a door there); there is a door between the workshop and the garage (presuming the door meets separation requirements); the garage side of the workshop walls are covered with 1/2" gypsum board minimum; the garage separation continues either up the wall to the underside of the roof sheathing or as a ceiling over the garage - either option separating the garage from the living space and the workshop, which is 'part of' the living space as described.

    2) People use solvents inside the dwelling all the time for their hobbies - there is no prohibition against that either.

    Why would someone want to include a workshop in with the living area air conditioning system, which allows dust, sawdust, vapors, and everything done or worked on in the workshop to be exchanged with the living space air?

    It's allowed ... and "you can't fix stupid".

    The answer for the buyer is simple - if they don't want all those things in the house living space, disconnect and close off that supply and return ... if the buyer doesn't mind and prefers to have the workshop with air conditioning ... so be it.

    I would write it in the report noting that the workshop was part of the air conditioning system for the living space, and that can lead to (list the things it can lead to, such as 'saw dust as a condiment in the food' or whatever you think is not a good idea) ... then point out that the fix is simple - close off those ducts and seal them up.

    Then let the client decide what they want ... they may like saw dust on their burgers and the smell of lacquer thinner in the air (when I resprayed my car in the garage, there is no ductwork connection between the garage and the house ... but there was definitely a lacquer thinner smell in the air in the house for a day or two - that stuff dissipates and goes everywhere).

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  3. #3
    Join Date
    Nov 2011
    Location
    Sedona, Arizona
    Posts
    20

    Default Re: House HVAC system also supplies workshop off garage?

    "Saw dust as a condiment on your food" I love that!!! Thanks Jerry.

    JP


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