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  1. #1
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    Default Fireplace flue too close to a window?

    Can someone look at the pictures and tell me if the this chimney flue is too close to these three master bedroom windows?

    Thanks, Jim Murphy

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    Default Re: Fireplace flue too close to a window?

    To reframe the question into another question: What distance is that vent supposed to be from a vertical wall?

    Windows or no windows.

    What are the two basic rules for chimneys and vents? (I'm not sure it meets any of the rules for vents.)

    Here is a start, the chimney rule is easier to remember: 3-2-10. (The chimney rule does not apply to that, this is just a 'jog memory' note on those two rules.)

    Jerry Peck
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    Default Re: Fireplace flue too close to a window?

    Added this for clarification:

    Is that a "fireplace" vent as stated in the title, and if so, is that a "gas fireplace" vent?

    It makes a difference because if that is a wood burning fireplace chimney, then to start with is the high wind gas vent cap is completely wrong.

    If it is a gas burning fireplace vent (instead of a chimney), then the gas vent heights still apply, except that a fireplace vent in larger in diameter and thus will have higher height requirements (but the same distance to a vertical wall applies, as I recall).

    Jerry Peck
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    Default Re: Fireplace flue too close to a window?

    Quote Originally Posted by Jerry Peck View Post
    Added this for clarification:

    Is that a "fireplace" vent as stated in the title, and if so, is that a "gas fireplace" vent?

    It makes a difference because if that is a wood burning fireplace chimney, then to start with is the high wind gas vent cap is completely wrong.

    If it is a gas burning fireplace vent (instead of a chimney), then the gas vent heights still apply, except that a fireplace vent in larger in diameter and thus will have higher height requirements (but the same distance to a vertical wall applies, as I recall).
    Thanks Jerry, it has been a while since I have been on this site. It is a gas burning fireplace vent so I believe part or most of the 3/2/10 rule apply.


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    Default Re: Fireplace flue too close to a window?

    Quote Originally Posted by JIM MURPHY View Post
    is a gas burning fireplace vent so I believe part or most of the 3/2/10 rule apply.
    Jim, the gas vent clearance would apply, not the chimney 3, 2-10 rule.

    I'm on my phone so I'm going from memory, but a gas vent needs to be 2 feet higher than a vertical surface within 8 feet, minimum height varies depending on the size of the vent and the slope of the roof (which doesn't matter with the vent within 8 feet of the wall).

    Jerry Peck
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    Default Re: Fireplace flue too close to a window?

    Jim,

    From the IRC: (bold and underlining are mine)

    G2427.6.4 (503.6.5)Gas vent terminations.
    - A gas vent shall terminate in accordance with one of the following:
    - - 1. Gas vents that are 12 inches (305 mm) or less in size and located not less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate above the roof in accordance with Figure G2427.6.4.
    - - 2. Gas vents that are over 12 inches (305 mm) in size or are located less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate not less than 2 feet (610 mm) above the highest point where they pass through the roof and not less than 2 feet (610 mm) above any portion of a building within 10 feet (3048 mm) horizontally.
    - - 3. As provided for direct-vent systems in Section G2427.2.1.
    - - 4. As provided for appliances with integral vents in Section G2427.2.2.
    - - 5. As provided for mechanical draft systems in Section G2427.3.3.

    In 2. above, that first "or" (which I made bold and underlined) is a critical word; also, the "and" (which I made bold and underlined) is also a critical word).

    Based on the above, and regardless of size of the vent, it reads like this "Gas vents that ... or are located less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate ... and not less than 2 feet (610 mm) above any portion of a building within 10 feet (3048 mm) horizontally"

    That gas vent rule is not as easy to remember as the 3, 2-10 chimney rule as there is a 'within 8 feet of a wall or similar obstruction' condition in it.

    Jerry Peck
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    Default Re: Fireplace flue too close to a window?

    Quote Originally Posted by Jerry Peck View Post
    Jim,

    From the IRC: (bold and underlining are mine)

    G2427.6.4 (503.6.5)Gas vent terminations.
    - A gas vent shall terminate in accordance with one of the following:
    - - 1. Gas vents that are 12 inches (305 mm) or less in size and located not less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate above the roof in accordance with Figure G2427.6.4.
    - - 2. Gas vents that are over 12 inches (305 mm) in size or are located less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate not less than 2 feet (610 mm) above the highest point where they pass through the roof and not less than 2 feet (610 mm) above any portion of a building within 10 feet (3048 mm) horizontally.
    - - 3. As provided for direct-vent systems in Section G2427.2.1.
    - - 4. As provided for appliances with integral vents in Section G2427.2.2.
    - - 5. As provided for mechanical draft systems in Section G2427.3.3.

    In 2. above, that first "or" (which I made bold and underlined) is a critical word; also, the "and" (which I made bold and underlined) is also a critical word).

    Based on the above, and regardless of size of the vent, it reads like this "Gas vents that ... or are located less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate ... and not less than 2 feet (610 mm) above any portion of a building within 10 feet (3048 mm) horizontally"

    That gas vent rule is not as easy to remember as the 3, 2-10 chimney rule as there is a 'within 8 feet of a wall or similar obstruction' condition in it.
    Again thanks Jerry!

    I have copied this and will kept it in my files to reference back to. Plus I have a reference when the builder tells me I do not know what I am talking about.

    Good corresponding with you again.

    Stay healthy!!!

    Jim Murphy


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    Default Re: Fireplace flue too close to a window?

    Jim,

    Some builders seem to need the assistance of a "secret decoder ring" in order to understand what the code says, this may help you 'break the code' for those builders:

    G2427.6.4 (503.6.5)Gas vent terminations.
    - A gas vent shall terminate in accordance with one of the following:

    - - means a gas vent for any gas appliance

    - - 1. Gas vents that are 12 inches (305 mm) or less in size and located not less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate above the roof in accordance with Figure G2427.6.4.

    - - - means that, for gas vents which are not larger than 12 inches in size
    - - - and
    - - - are located more than 8 feet from a wall or similar obstruction
    - - - the gas vent shall terminate as shown in the figure (also print that figure and its table) for minimum heights of the vent for various roof slopes

    - - 2. Gas vents that are over 12 inches (305 mm) in size or are located less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate not less than 2 feet (610 mm) above the highest point where they pass through the roof and not less than 2 feet (610 mm) above any portion of a building within 10 feet (3048 mm) horizontally.

    - - - means that, for gas vents which
    - - - are larger than 12 inches in size
    - - - or
    - - - are located 8 feet or less from a wall or similar obstruction
    - - - must be at least 2 feet higher, measured on the high side where it passes through the roof
    - - - than any part of a building (doesn't say "the" building, just "a" building, which could be another building)
    - - - i.e., 2 feet higher than any part of any building which is within 10 feet horizontally of the vent

    - - 3. As provided for direct-vent systems in Section G2427.2.1.

    - - - means basically per the manufacturer's installation instructions plus some other things may apply

    - - 4. As provided for appliances with integral vents in Section G2427.2.2.

    - - - means basically per the manufacturer's installation instructions plus some other things may apply

    - - 5. As provided for mechanical draft systems in Section G2427.3.3.

    - - - means basically per the manufacturer's installation instructions, plus some other things may apply

    Last edited by Jerry Peck; 10-20-2020 at 09:00 AM. Reason: Speelin'
    Jerry Peck
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  9. #9
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    Smile Re: Fireplace flue too close to a window?

    Quote Originally Posted by Jerry Peck View Post
    Jim,

    Some builders seem to need the assistance of a "secret decoder ring" in order to understand what the code says, this may help you 'break the code' for those builders:

    G2427.6.4 (503.6.5)Gas vent terminations.
    - A gas vent shall terminate in accordance with one of the following:

    - - means a gas vent for any gas appliance

    - - 1. Gas vents that are 12 inches (305 mm) or less in size and located not less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate above the roof in accordance with Figure G2427.6.4.

    - - - means that, for gas vents which are not larger than 12 inches in size
    - - - and
    - - - are located more than 8 feet from a wall or similar obstruction
    - - - the gas vent shall terminate as shown in the figure (also print that figure and its table) for minimum heights of the vent for various roof slopes

    - - 2. Gas vents that are over 12 inches (305 mm) in size or are located less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate not less than 2 feet (610 mm) above the highest point where they pass through the roof and not less than 2 feet (610 mm) above any portion of a building within 10 feet (3048 mm) horizontally.

    - - - means that, for gas vents which
    - - - are larger than 12 inches in size
    - - - or
    - - - are located 8 feet or less from a wall or similar obstruction
    - - - must be at least 2 feet higher, measured on the high side where it passes through the roof
    - - - than any part of a building (doesn't say "the" building, just "a" building, which could be another building)
    - - - i.e., 2 feet higher than any part of any building which is within 10 feet horizontally of the vent

    - - 3. As provided for direct-vent systems in Section G2427.2.1.

    - - - means basically per the manufacturer's installation instructions plus some other things may apply

    - - 4. As provided for appliances with integral vents in Section G2427.2.2.

    - - - means basically per the manufacturer's installation instructions plus some other things may apply

    - - 5. As provided for mechanical draft systems in Section G2427.3.3.

    - - - means basically per the manufacturer's installation instructions, plus some other things may apply
    Again as always, Thanks.

    I will print this out for my fuure references and builders!


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    Default Re: Fireplace flue too close to a window?

    As I've been saying since I joined in 2007, refer to the listed instructions for that appliance. The manual is part of the appliance listing.

    In this case, it appears to be Dura-Vent B-vent but could be their direct vent. It is NOT a "chimney". Most direct vents allow for very close clearances to openings, walls, and similar structures. Locate the appliance rating plate, pull up the manual online and you have your answer.

    Keep the fire in the fireplace.

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    Default Re: Fireplace flue too close to a window?

    Quote Originally Posted by Bob Harper View Post
    In this case, it appears to be Dura-Vent B-vent but could be their direct vent.
    Agreed, could be direct vent cap, but with a comparison between the two, the direct vent is 'taller and narrower' in appearance than the 'more square look" of the high wind B vent cap.

    Locate the appliance rating plate, pull up the manual online and you have your answer.
    I always seem to forget to include that part of the answer, albeit that is included in the code section, item 3. I think it was ... but that is a key aspect to document for every vented gas appliance.

    Jerry Peck
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    Default Re: Fireplace flue too close to a window?

    Quote Originally Posted by Jerry Peck View Post
    Some builders seem to need the assistance of a "secret decoder ring" in order to understand what the code says, this may help you 'break the code' for those builders:
    A really handy version of the "secret decoder rings" are the CodeCheck flip books. They are affordable and have nifty little pictures of the way things should be. CCPM5 - 117b - B Vent Termination.jpg

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    Default Re: Fireplace flue too close to a window?

    Quote Originally Posted by Gunnar Alquist View Post
    A really handy version of the "secret decoder rings" are the CodeCheck flip books. They are affordable and have nifty little pictures of the way things should be.
    At a quick glance at that drawing, I saw at least two errors.

    Jerry Peck
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    Default Re: Fireplace flue too close to a window?

    Gunnar,

    I looked at that drawing on my phone, so I didn't want to commit to more than the two I saw for sure, here is an annotated drawing showing what I was referring to, and adding in the one I wasn't sure about. One of the two is shown wrong in one part of the drawing, then shown correctly in another part of the drawing - see my annotations.

    Minor aspects? Depends on "how close" one is measuring, but based on the code wording, accuracy is important.

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    Default Re: Fireplace flue too close to a window?

    Jerry,

    I'll pass your diagram and remarks on to Douglas and Skip.



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    Default Re: Fireplace flue too close to a window?

    DuraVent caps for B-vent and direct vent will fit each other-trust me. The close up detail is seeing the louvers near the base where the air enters the DV cap into the concentric space. It's a nominal 6"x4" cap. However, a std. B-vent cap will fit over the common 6 5/8" direct vent pipe. Typically, the owner calls complaining the flame "ghosts" out from oxygen starvation and nobody can figger' out why.

    Yep, height above the roof line is from the uphill junction of the vent and it's to the flue gas outlet -not the top of the rain cap. Where flue tiles extend more than 4" above a masonry crown then a liner protrudes that, keep in mind the 'chimney' cannot have more than 2-4" of tile exposed. Where someone left a foot of tile exposed you should be recommending extending the chimney to meet the tile exposure requirement. Then any liner contained within can be justified. A naked flue tile will get chilly and kill the draft.

    Keep the fire in the fireplace.

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    Default Re: Fireplace flue too close to a window?

    Quote Originally Posted by Bob Harper View Post
    DuraVent caps for B-vent and direct vent will fit each other-trust me. The close up detail is seeing the louvers near the base where the air enters the DV cap into the concentric space.
    Yet one more reason why the inspector needs to 'get up close and personal' with it - to see those louvers in the concentric space, and when doing the roof first, make note of what is seen (photos, photos, and more photos work great for later 'remembering' what one saw when looking at something), this will give the inspector better knowledge of what is supposed to be there after inspecting the gas appliance and getting the nameplate label information.

    Oops, it is a DV gas appliance? I don't remember if that was a DV cap I saw on the roof ... great, now I have to go back on the roof and look at that cap again (or I can just look at the photos I took while looking at the cap).

    One of the best "tool" advances ever made for inspectors was the digital camera. For those 'old time' inspectors, think of still having to deal with 35 mm film and its developing costs and delays, or Polaroids and their limitations.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
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