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    Default Requirements for masonry chimney attic fire block

    I hired a fire specialist to checkout the masonry fireplace in my 40 year old home. The fireplace doesn't draw properly and he did find some clues on why. The fire safety issue that I need help with is the gap in the attic around the chimney. He stated that the gap between the dry wall framing and the chimney needs fire block on the attic side of the ceiling. Does this mean fire rated sheet rock should be installed at the attic floor line or metal sheathing should be installed? With either material, is caulking used between the chimney and the Sheetrock/sheathing? I have a contractor who says fire-rated Sheetrock but I can only find pictures with metal sheathing. And I don't understand the code references in earlier threads. Can anyone help with the proper way to solve this gap on the attic side of a masonry chimney?

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    Default Re: Requirements for masonry chimney attic fire block

    I use GP Densarmor drywall, and my flexible grout. I have many examples in captioned photo albums. Here is one as an inserted photo. Please see this photo in context at page 120 of the full job album.

    The flexible grout is a wonderful product described at the link. I still seek manufacturers of this product. Please ask me for a free sample.
    IMG_4475_25_pct.jpg

    Here is another photo, album page 128.
    IMG_4484_35.jpg


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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Phillip Norman View Post
    I use GP Densarmor drywall, and my flexible grout. I have many examples in captioned photo albums. Here is one as an inserted photo. Please see this photo in context at page 120 of the full job album.

    The flexible grout is a wonderful product described at the link. I still seek manufacturers of this product. Please ask me for a free sample.
    From your link:
    "
    This is very-crummy sealing of a wall header by "the competition", using spray foam.
    "

    While you may look at that as a "very-crummy sealing ... using spray foam", that is not a "spray foam" but it is listed and labeled for that use ... while your material is not listed and labeled for that use.

    Have you had your product tested? Have you had your product listed? Those need to be done before you have it manufactured so avoid the waste of all the time, effort, and money of manufacturing a product which is not allowed to be used.

    Hopefully ... you have used that on your house ONLY ... otherwise you have taken on A LOT of liability.

    I'm not against new products being developed, or against new products being tested, only against unknown products being tested on unsuspecting people (that is what you are doing if you have used your product on anyone else's house, and even offering free samples).

    Then again ... you are advertising your product on the internet ... so it must be true ...

    ... yeah, right ... but that is what many people think.
    - https://www.youtube.com/watch?v=v_CgPsGY5Mw

    Last edited by Jerry Peck; 12-10-2015 at 07:13 AM. Reason: tried to fix some quotes which came out weird
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    Default Re: Requirements for masonry chimney attic fire block

    Lee,

    The building code requires fireblocking to cut off the passage of fire within concealed spaces in a building of combustible construction, including the space around a chimney where it penetrates floors and ceilings. The building code also does not allow combustible material to be within 2" of a masonry fireplace or chimney, therefore fireblocking around a chimney must be of non-combustible construction. The only 2 non-combustible materials listed in the code which are approved for fireblocking are 1/2" gypsum board and 1/4" cement millboard. As a code official I would also allow other non-combustible materials such as sheet metal or grout, although it could be argued that these materials would too easily transfer heat to the combustible materials that they are anchored to and supposed to be protecting. The gypsum board need not be fire-rated. Hopefully that clarifies the situation for you.

    Thom Huggett, PE, SE, CBO

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    Default Re: Requirements for masonry chimney attic fire block

    Metal fireblocking is used around every prefab chimney.

    Gypsum wallboard (even Type X) is a combustible material. The confusion comes from the the fact that it is used in fire-rated assemblies. It slows the spread of fire, but is combustible.

    Rotten cotton (mineral fiber insulation) is often used to firestop areas such as gaps between framing and chimneys.


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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Mark Reinmiller View Post
    Rotten cotton (mineral fiber insulation) is often used to firestop areas such as gaps between framing and chimneys.
    "Rotten cotton" That is a new term for me, never heard rock wool called that.

    While rock wool is a mineral fiber insulation, so is fiberglass insulation, but fiberglass insulation is very limited heat limits then it melts and is useless. Typically, when mineral fiber insulation is specified, it will state rock wool or 'other than fiberglass' ... although I do occasionally see 'mineral fiber insulation' on plans, and when asked if fiberglass is acceptable, the response is always to the affect of 'no, rock wool, not fiberglass, needs to be used'.

    Even with rock wool, the gap needs to be such that the required depth can be packed in and it if will not stay in by itself, then a means to keep in it place needs to be used.

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    Default Re: Requirements for masonry chimney attic fire block

    Rock wool and fiberglass are not fire block.
    NBC follows;
    3.1.9.1. Fire Stopping of Service PenetrationsPiping, tubing, ducts, chimneys, electrical wires and cables, totally enclosednoncombustible raceways, electrical outlet boxes and other similar buildingservices that penetrate a membrane forming part of an assembly required tohave a fire-resistance rating, or a fire separation, shall be a. tightly fitted, orb. sealed by a firestop system that, when subjected to the fire testmethod in CAN4-S115-M, "Standard Method of Fire Tests of FirestopSystems," has an F rating not less than the fire-protection ratingrequired for closures in the fire separation. (See A- 9.10.9.6.(1) inAppendix A.)(See also Article 3.1.9.4. for penetrations involving combustible drain,waste and vent piping.)2. Piping, tubing, ducts, chimneys, electrical wires and cables, totallyenclosed noncombustible raceways, electrical outlet boxes and othersimilar building services that penetrate a firewall or a horizontal fireseparation that is required to have a fire resistance rating in conformancewith Article 3.2.1.2., shall be sealed at the penetration by a fire stopsystems that, when subjected to the fire test method in CAN4-S115-M,"Standard Method of Fire Tests of Firestop Systems," has an FT rating notless than the fire-resistance rating for the fire separation.

    Fire span 40 / 90 Thermafiber.
    http://products.lwsupply.com/content...pan_40_90.html

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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Lee Richards View Post
    I hired a fire specialist to checkout the masonry fireplace in my 40 year old home. The fireplace doesn't draw properly and he did find some clues on why.
    There could be many reasons for the lack of draw.
    Masonry chimneys, I first look at;
    1: Is the chimney high enough.
    If I recall 15' feet is a minimum, but do not quote me on that.
    2: Then the flue projection. It should be 4" inches above the crown.
    3: Are there 2 flues? One for the chimney and another for the furnace.
    4: Then your clean out. If it is filled or dirty, it can effect the draw.
    5: Is your home back drafting?

    What did the fire specialist have to say other than what you posted?

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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by ROBERT YOUNG View Post
    Rock wool and fiberglass are not fire block.
    NBC follows;
    3.1.9.1. Fire Stopping of Service PenetrationsPiping, tubing, ducts, chimneys, electrical wires and cables, totally enclosednoncombustible raceways, electrical outlet boxes and other similar buildingservices that penetrate a membrane forming part of an assembly required tohave a fire-resistance rating, or a fire separation, shall be a. tightly fitted, orb. sealed by a firestop system that, when subjected to the fire testmethod in CAN4-S115-M, "Standard Method of Fire Tests of FirestopSystems," has an F rating not less than the fire-protection ratingrequired for closures in the fire separation. (See A- 9.10.9.6.(1) inAppendix A.)(See also Article 3.1.9.4. for penetrations involving combustible drain,waste and vent piping.)2. Piping, tubing, ducts, chimneys, electrical wires and cables, totallyenclosed noncombustible raceways, electrical outlet boxes and othersimilar building services that penetrate a firewall or a horizontal fireseparation that is required to have a fire resistance rating in conformancewith Article 3.2.1.2., shall be sealed at the penetration by a fire stopsystems that, when subjected to the fire test method in CAN4-S115-M,"Standard Method of Fire Tests of Firestop Systems," has an FT rating notless than the fire-resistance rating for the fire separation.

    Fire span 40 / 90 Thermafiber.
    http://products.lwsupply.com/content...pan_40_90.html
    I agree that fiberglass is not firestopping. I don't think anyone said it was. Rock Wool is a trademark for mineral fiber insulation. Mineral fiber insulation is commonly used and approved as firestopping, as shown in your link, or the link below.

    https://www.fastenal.com/products/details/65940


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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by ROBERT YOUNG View Post
    Rock wool and fiberglass are not fire block.
    NBC follows;
    3.1.9.1. Fire Stopping of Service PenetrationsPiping, tubing, ducts, chimneys, electrical wires and cables, totally enclosednoncombustible raceways, electrical outlet boxes and other similar buildingservices that penetrate a membrane forming part of an assembly required tohave a fire-resistance rating, or a fire separation, shall be a. tightly fitted, orb. sealed by a firestop system that, when subjected to the fire testmethod in CAN4-S115-M, "Standard Method of Fire Tests of FirestopSystems," has an F rating not less than the fire-protection ratingrequired for closures in the fire separation. (See A- 9.10.9.6.(1) inAppendix A.)(See also Article 3.1.9.4. for penetrations involving combustible drain,waste and vent piping.)2. Piping, tubing, ducts, chimneys, electrical wires and cables, totallyenclosed noncombustible raceways, electrical outlet boxes and othersimilar building services that penetrate a firewall or a horizontal fireseparation that is required to have a fire resistance rating in conformancewith Article 3.2.1.2., shall be sealed at the penetration by a fire stopsystems that, when subjected to the fire test method in CAN4-S115-M,"Standard Method of Fire Tests of Firestop Systems," has an FT rating notless than the fire-resistance rating for the fire separation.

    Fire span 40 / 90 Thermafiber.
    http://products.lwsupply.com/content...pan_40_90.html
    Robert,

    You are mixing up two separate and distinct terms: fireblocking and firestopping.

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    Default Re: Requirements for masonry chimney attic fire block

    Thanks for the correction, I meant mineral wool or MMMF.
    Ops.
    Yes Rockwool is a patent material. I am sure the stake holders are happy.
    Thanks for the reminder Jerry:-)

    Now maybe I misread the thread. Requirements for masonry chimney attic fire block.
    In situations such as this, a fire stop requirement can do the same thing or am I following the "ass/u/me" rule;-)

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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by ROBERT YOUNG View Post
    Now maybe I misread the thread. Requirements for masonry chimney attic fire block.
    In situations such as this, a fire stop requirement can do the same thing or am I following the "ass/u/me" rule;-)
    See part I underlined in your quote below:

    Quote Originally Posted by ROBERT YOUNG View Post
    Rock wool and fiberglass are not fire block.
    NBC follows;
    3.1.9.1. Fire Stopping of Service Penetrations ... shall be sealed at the penetration by a fire stop systems that, when subjected to the fire test method in CAN4-S115-M,"Standard Method of Fire Tests of Firestop Systems," has an FT rating notless than the fire-resistance rating for the fire separation.
    A firestop is part of a firestop system, tested, listed, and has a design number for reference, the firestop system specifies everything about it.

    A fireblock is just approved material applied in the approved manner:
    - From the IRC:
    - - R302.11.1 Fireblocking materials. - - - Except as provided in Section R302.11, Item 4, fireblocking shall consist of the following materials.
    - - - - 1. Two-inch (51 mm) nominal lumber.
    - - - - 2. Two thicknesses of 1-inch (25.4 mm) nominal lumber with broken lap joints.
    - - - - 3. One thickness of 23/32-inch (18.3 mm) wood structural panels with joints backed by 23/32-inch (18.3 mm) wood structural panels.
    - - - - 4. One thickness of 3/4-inch (19.1 mm) particleboard with joints backed by 3/4-inch (19.1 mm) particleboard.
    - - - - 5. One-half-inch (12.7 mm) gypsum board.
    - - - - 6. One-quarter-inch (6.4 mm) cement-based millboard.
    - - - - 7. Batts or blankets of mineral wool or glass fiber or other approved materials installed in such a manner as to be securely retained in place.
    - - - - 8. Cellulose insulation installed as tested for the specific application.

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    Default Re: Requirements for masonry chimney attic fire block

    Marc, Jerry as usual always enlightening.
    I like the rotten cotton as well:-) Cool!

    Also, Fireblocking; The purpose of fire blocking is to prevent fire from spreading through the concealed spaces of a building.
    Firestopping.
    A firestop is a fire protection system made of various components used to seal openings and joints in fire-resistance rated wall and/or floor assemblies.

    Getting back to; Requirements for masonry chimney attic "fire block" and a chimney not effectively drafting...Post #1He stated that the gap between the dry wall framing and the chimney needs fire block on the attic side of the ceiling.

    I see Dimensional 2x4" inch material or laminated studs normally.
    I can not see how that would effect draw but then again you learn something new every day.
    Questions: If a fire rated material blocks, would you consider it a compliant fire blocking in a chimney protrusion of a homes structural assembly? If not, why?

    Read the list below.
    ICC rates Fiberglass a fireblocking material.
    #7
    I can see why home owners and builders get confused.

    R302.11.1 Fireblocking materials.

    As per the ICC R302.11.1 and
    1. Two-inch (51 mm) nominal lumber.2. Two thicknesses of 1-inch (25.4 mm) nominal lumber with broken lap joints.3. One thickness of 23/32-inch (18.3 mm) wood structural panels with joints backed by 23/32-inch (18.3 mm) wood structural panels.4. One thickness of 3/4-inch (19.1 mm) particleboard with joints backed by 3/4-inch (19.1 mm) particleboard.5. One-half-inch (12.7 mm) gypsum board.6. One-quarter-inch (6.4 mm) cement-based millboard.7. Batts or blankets of mineral wool or glass fiber or other approved materials installed in such a manner as to be securely retained in place.

    It appears fiberglass in some manufactured state exists as a fire blocking component .


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    Default Re: Requirements for masonry chimney attic fire block

    Hi Robert,

    This caught my attention in your post above,

    4: Then your clean out. If it is filled or dirty, it can effect the draw.
    Can you clarify for me why a dirty clean-out would affect the draw? Are you thinking of a fresh air intake to the fire box found on the floor of the hearth?

    Cheers,


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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by ROBERT YOUNG View Post
    Getting back to; Requirements for masonry chimney attic "fire block" and a chimney not effectively drafting.
    .
    Post #1 He stated that the gap between the dry wall framing and the chimney needs fire block on the attic side of the ceiling.
    .
    I can not see how that would effect draw but then again you learn something new every day.


    Correct (as I understand what you are saying) - that a space around the chimney does not affect the drafting of the fireplace.

    I think that comment was more of a 'also' type comment, as in 'oh, by the way, the chimney was not properly fireblocked around at the ceiling' type of comment.

    I see Dimensional 2x4" inch material or laminated studs normally.


    Neither of which should be within 2" of the fireplace chimney.


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    Default Re: Requirements for masonry chimney attic fire block

    Hi Ray.

    Now I am stating this from experience.
    Nothing more.

    The ash dump void can effect draft.
    Look at the ash dump in the illustration.
    Many equations can effect draft.

    fireplace.JPG
    That being said, not all fire places have ash dumps nor do all homes have basements.

    In fireplaces, fire boxes and stoves, not all are the same.

    Do a test. Burn a fire, go into your basement with a smoke pencil and tell me what happens at the ash dump door.


    The solid fuel requires combustion air and there is no better place than under the solid fuel.

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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Jerry Peck View Post
    Correct (as I understand what you are saying) - that a space around the chimney does not affect the drafting of the fireplace.

    I think that comment was more of a 'also' type comment, as in 'oh, by the way, the chimney was not properly fireblocked around at the ceiling' type of comment.

    [/COLOR]

    Neither of which should be within 2" of the fireplace chimney.
    I know what you are saying Jerry. The 2" rule if I remember correctly.

    I have seen more wood blocking on chimneys.
    Mid to late 1950's and early sixties homes in a particular area of Montreal.
    how many homies go into the attic anywho?

    I rebuilt a chimney in 2006. 20-25 courses below the roof-line had to be rebuilt.
    Excessive laterals cracks.

    The masons built into and on the end the end rafter tail instead of having a carpenter cut of the excess wood.
    The roof deck was also directly touching the masonry chimney as well.
    Snow would load the roof, the rafter would deflect and transmit force into the masonry.
    During the season the deck would shift and so would the masonry.

    So I see all manners of defects. You just have to look.

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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Jerry Peck View Post
    Correct (as I understand what you are saying) - that a space around the chimney does not affect the drafting of the fireplace.

    I think that comment was more of a 'also' type comment, as in 'oh, by the way, the chimney was not properly fireblocked around at the ceiling' type of comment.

    [/COLOR]

    Neither of which should be within 2" of the fireplace chimney.
    You are correct, Poor example on my part. Ops.

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    Default Re: Requirements for masonry chimney attic fire block

    Robert,

    That illustration is lacking one detail, a lid (usually cast iron) on the opening at the firebox. The other parts of your illustration look correct. With a lid on the firebox draft should be minimal or non existent if the basement lid is in place.

    But like you say, best to try theories with a smoke pencil.


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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Raymond Wand View Post
    But like you say, best to try theories with a smoke pencil.
    I'm not your fireplace expert here - Bob H. is, but ... if you have to use a smoke pencil to find the draft for a fireplace ... you have a major draft problem there ... ... just sayin' ...

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    Default Re: Requirements for masonry chimney attic fire block

    .. and that's why you're the expert. Just sayin.. ba da boom, ba da bing!


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    Default Re: Requirements for masonry chimney attic fire block

    The effectiveness of the lid is visually explained by the water stains you observe during home inspections. It is not air tight. There is enough air to start a draft required to combust the solid fuel.

    When the solid fuel is sufficiently ignited, oxygen is used from all accessible locations.

    - - - Updated - - -

    Quote Originally Posted by Jerry Peck View Post
    I'm not your fireplace expert here - Bob H. is, but ... if you have to use a smoke pencil to find the draft for a fireplace ... you have a major draft problem there ... ... just sayin' ...
    Bob H. ?
    Nickname?


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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by ROBERT YOUNG View Post
    The effectiveness of the lid is visually explained by the water stains you observe during home inspections. It is not air tight. There is enough air to start a draft required to combust the solid fuel.

    When the solid fuel is sufficiently ignited, oxygen is used from all accessible locations.
    That is why those metal thingys (you know "thingys" - technical term ) are used which hold the logs up off the bottom of the fireplace ...

    We even have them for out gas log set - to make the ceramic logs look more 'realistic', rock wool embers cover the bottom to look like burning ash ...

    Bob H. ?
    Nickname?


    Bob Harper ... his tagline is 'Keep the fire in the fireplace'.

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    Default Re: Requirements for masonry chimney attic fire block

    Thanks.
    I thought you where referring to someone that has expertise.

    Ash dumps being utilized for better venting have been around for some time.
    The ash dump pit is a common source for fireplace makeup air.
    A savvy handyman / home owner can utilize the chamber to increase home comfort, heating energy and provide outside air as for the fire place combustion air.

    Here is a product that makes my point about ash dump makeup air and for effective drafting.
    Vented ash dump door.
    http://www.northlineexpress.com/vent...cioa-9230.html
    This cast iron ash dump has an outside air intake controlled by sliding shutter. Controls outside air source from inside the fireplace. Keeps the cold air out when not in use. Outside air would typically come from the ash dump cavity through a chimney clean out door. Inside lip 4.5" x 8 3/4" and the outside dimensions are 5 3/8 " x 9 3/4".

    I have read up on drafting and forgot most of what I read and was taught unfortunately.
    Here is a small piece on chimney fireplace design.
    http://www.askthebuilder.com/fireplace-design-dimensions/

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    Default Re: Requirements for masonry chimney attic fire block

    Something about using the ash dump for draft air, combustion air, or make up air for a fireplace just seems counter-intuitive ... something to do with what is dumped into the ash dump and intending air to circulate in from outside, over and through the ash, and then back up into the interior of the house ... seem counter-intuitive to anyone else?

    I mean, who intentionally installs something which is intended to blow ash up into the house?

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    Default Re: Requirements for masonry chimney attic fire block

    Counter-intuitive?
    To what degree?
    Please explain.

    Ash particles from the ash dump are directed upstream in the oxygen flow.
    The particles will be directed into the combustion process, pass the damper, up the throat, into the flue and out the chimney.






    Last edited by ROBERT YOUNG; 12-12-2015 at 07:43 AM.
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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by ROBERT YOUNG View Post
    Counter-intuitive?
    To what degree?
    Please explain.

    Ash is lightweight.

    Ash blows around easily in the wind.

    Installing an open ash dump door is intended to allow wind (draft) into the ash dump.

    Ash blows around easily in the wind.

    The wind is intended to blow (draft) up into the fireplace (and thus inside the house).

    When there is no fire in the fireplace ... there is still wind outside ... which still blows (drafts) up into the fireplace and into the interior of the living space.

    Why would anyone intentionally do that?

    That is what is counter-intuitive.

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    Default Re: Requirements for masonry chimney attic fire block

    I see your point.
    The idea is not to use the ash dump.
    Clean the ashes out after every fire.
    Personally I never used them but cleaned many.

    A quick story.
    Friends, homesteaders as they liked to call themselves, asked me about an ongoing issue with there main source of heat, there wood cook stove.
    He was a good half decent GC by the way.
    I inspected the cook unit and chimney, plus all the appliance's attachments and all connections.

    For over 2 decades he thought it was normal to see the single walled lateral flue pipe mounted into the chimney turn orange.
    Now red was to hot he said as we discussed his annoyance at drafting.

    2 times the fire department came to put out a chimney fire.
    Creosote build up by the way.
    Even the fire marshal and one of the veteran firemen could not figure out the issue, or so he said, but they did say to clean out his chimney sleeves often.

    after 2 hours I hypothesized:
    1: The ash dump tray was never cleaned as I started passing by more frequently and without giving them notice.
    I recommend constant cleaning. Always clean it!
    2: As with the fire marshal, I echoes, clean you flue and added burn creosote fee logs.
    He said they really work! Hmm...I guess he is not smokey the bears relative.
    3: The vent cap restricted flow. I recommended buy one that is higher in profile and has the ember guard that is not so restricting. The original was tight stainless with a mesh like a screen door. I was amazed they sell them like that. He said it came with the chimney kit.

    I returned to good reviews, but he said the fire truck was there again last night encase the home burn down. The chimney itself was red inside the kitchen.
    Wow, I wish I was there!!!

    I ashed him, are your sure you followed my recommendations?
    He said yes, and that the stove was working much better yet the chimney was red after they came in from doing there chores in the field bring in Charley the hoarse and cleaning up the barn so they call the fire truck.

    I was stumped!!!
    A week later he told me he did not clean out the ash dump drawer in the stove.
    That his uncle, second or third generation of the founder of the home stead in the late 1880's, told him to always leave ashes in a wood stove tray and also when you use the fireplace.
    I was dumbfounded, truly.
    Old family folk lore that almost set the home alight many times.

    Once he changed the insulated chimney sleeves and keep the wood stoves ash tray clean every operated in normal perimeters.

    Drafting, a means to allow combustion air, but drafting also refers to exhausting spent fuel.

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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by ROBERT YOUNG View Post
    I see your point.
    The idea is not to use the ash dump.
    That is why they are there. And that is why they are called ash dumps.

    Clean the ashes out after every fire.
    Who does that? And are they "clean", as in totally clean, after cleaning? I doubt it.

    Once he changed the insulated chimney sleeves and keep the wood stoves ash tray clean every operated in normal perimeters.
    And it was the ash tray which resulted in proper operation? Nothing to do with replacing the insulated chimney sections?

    Either I am missing something ... or you are ... could be me ...

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Jerry Peck View Post
    Ash is lightweight.

    The wind is intended to blow (draft) up into the fireplace (and thus inside the house).
    What if there is no wind?
    Draft can be naturally manufactured and there lay the OP thread.


    When there is no fire in the fireplace ... there is still wind outside ... which still blows (drafts) up into the fireplace and into the interior of the living space.

    Why would anyone intentionally do that?

    That is what is counter-intuitive.
    As explained, it is not counter intuitive when done mindfully.
    As with a damper door, you close the ash dump off, or an exterior vent that is tied into the ash dump void, when the fire place is not in use.
    I feel it would be logical to so from inside a warm comfortable home myself.

    IMO, counter productive from an energy stand point would be to utilize manufactured habitable air as a means for solid fuel combustion.

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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Jerry Peck View Post
    1: That is why they are there. And that is why they are called ash dumps.



    2: Who does that? And are they "clean", as in totally clean, after cleaning? I doubt it.



    3: And it was the ash tray which resulted in proper operation? Nothing to do with replacing the insulated chimney sections?

    Either I am missing something ... or you are ... could be me ...
    1: I concur. But using that logic, are we still using wooden wagon wheels on cars?
    Jerry, as you well know, just because something was manufactured for a use in a component does not exclude that component from being modified.
    That is why building codes continually modify.

    2: Some do while I suspect others do not.

    3: I will not say that.
    It was a combination of manufacturing defects and maintenance deficiencies that culminated in the safety events.
    IMO, it is hard to know without doing controlled testing to see if the wood stove ash tray of that specific manufacturer was the initial cause of the events.

    Remember, Smokey the fire says, "Only you can prevent bears." Ha ha ha

    Please let me say this; I thank you for treating me with respect and having the patients to allow this drafting discussion to go this far. You and the others members are kind in doing so.
    You are a genuine professional Jerry .

    Lisa, I know you monitor Brain Hannagin's InspectionNews MB.
    It would be helpful to InterNACHI if their MB followed the same professional attitude.
    InterNACHI MB has lost to many good homies and mentors due to the Code Of Conduct certain members subscribe to. I think the term would be, Self anointed hubris.
    Too bad.
    So sad!

    Last edited by ROBERT YOUNG; 12-12-2015 at 09:20 AM.
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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by ROBERT YOUNG View Post
    As explained, it is not counter intuitive when done mindfully.
    As with a damper door, you close the ash dump off, or an exterior vent that is tied into the ash dump void, when the fire place is not in use.
    I feel it would be logical to so from inside a warm comfortable home myself.

    IMO, counter productive from an energy stand point would be to utilize manufactured habitable air as a means for solid fuel combustion.
    If the intent of the ash dump was to provide air for the fire, then, first of all, it would not be below the fire where the ashes could accumulate, second, it would not be called an ash dump, it would be located even with the fireplace floor and open to the outside, with a lined opening to the vent cover, and lastly, it would be called a combustion air vent (not an ash dump).

    But ... that is not where it is located, not what it is for, and not what it is called. That does not stop people from using a screw driver as a hammer, or a hammer as a wrench, or a wrench as a hammer ... just not what its intended purpose is. People use things for whatever use they want, regardless of the intended use, and that is what you are describing.

    Just because someone makes a product does not mean it should be used - take the flexible tailpieces for sinks as an example: they are allowed to be made; allowed to be stocked in warehouses, allowed to be sold, allowed to be bought ... but not allowed to be installed for use.

    Someone makes a pretty cast iron vented ash dump cover ... it lets the wind blow the ashes around, nonetheless, though, it is even advertised as a cover for an "ash dump" - even they know what that area is for.

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Jerry Peck View Post
    If the intent of the ash dump was to provide air for the fire, then, first of all, it would not be below the fire where the ashes could accumulate,

    second, it would not be called an ash dump, it would be located even with the fireplace floor and open to the outside, with a lined opening to the vent cover, and lastly, it would be called a combustion air vent (not an ash dump).
    I concur.
    I think it was engineered for its intended use.
    When was it engineered falls into play. Homes then where not as energy efficient, they were downright drafty.

    I think the above covers both the preliminary and secondary questions/statements.

    As we both agree on, not all fireplaces and ash dumps are created equal.
    I am providing a theory for overall drafting.

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    Default Re: Requirements for masonry chimney attic fire block

    Ash dumps are created for a purpose, that purpose is whythey called "ash dumps".

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: Requirements for masonry chimney attic fire block

    I concur with the respect to the purpose.
    The added benefit, an added source of combustion draft, no matter how small one considers it.

    As for, that purpose is why they called "ash dumps".
    Then why do they call the fireplace front the breast?
    Manufacturers do not manufacture fireplace bra's, nor do they sag and droop with age, and one does not get a slap in the face nor a glint of pleasure from the fireplace when their breasts are politely rubbed with one's hand in a caring manner.


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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by ROBERT YOUNG View Post
    I concur with the respect to the purpose.
    The added benefit, an added source of combustion draft, no matter how small one considers it.

    As for, that purpose is why they called "ash dumps".
    Then why do they call the fireplace front the breast?
    Manufacturers do not manufacture fireplace bra's, nor do they sag and droop with age, and one does not get a slap in the face nor a glint of pleasure from the fireplace when their breasts are politely rubbed with one's hand in a caring manner.
    They have been called such long before many decided that women needed to wear undergarments to shape women as man wanted the women shaped.

    Like the "breastplate" of old armor, should be self-explanatory to those who contemplate such things.

    That pit was called an ash dump because it was constructed into the fireplace bottom as a place to push/sweep the ashes out of the way, and to allow for one fire to be built on the remains of the previous fire.

    Trying to compare the drafting ability of air leakage, even with a vented cover, of an ash dump to that which comes in through the fireplace opening is, at best, ill-conceived and without much thought of the amount of air draft capability between the two openings, even if an ash dump had not exterior cover.

    Be that as it may, don't let logic or intended purposes get in your way. I'm with that.

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    Default Re: Requirements for masonry chimney attic fire block

    Ha Ha Ha.
    Love to see logic at work.

    The truth of the matter being, the wheel will always be Reinvented, or should I say redrafted.

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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Mark Reinmiller View Post
    Metal fireblocking is used around every prefab chimney.

    Gypsum wallboard (even Type X) is a combustible material. The confusion comes from the the fact that it is used in fire-rated assemblies. It slows the spread of fire, but is combustible.
    Mark,

    According to IBC Section 703.5 gypsum board is a non-combustible material. The core meets ASTM E-136 and the facing is less than 1/8" with a flame spread less than 50 according to ASTM E-84 (see IBC Section 703.5.2). I agree that it does burn, but the IBC does consider it non-combustible. That's why they cover the walls with it in Type I buildings (IBC Chapter 6).

    Thom Huggett, PE, SE, CBO

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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Thom Huggett View Post
    According to IBC Section 703.5 gypsum board is a non-combustible material. The core meets ASTM E-136 and the facing is less than 1/8" with a flame spread less than 50 according to ASTM E-84 (see IBC Section 703.5.2). I agree that it does burn, but the IBC does consider it non-combustible. That's why they cover the walls with it in Type I buildings (IBC Chapter 6).
    Yes and no.

    http://specsandcodes.typepad.com/the...struction.html

    Go down to "Gypsum Board Myths" (the yes part for your first part)

    Then to "Conclusion" (the no part for your last part)

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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Jerry Peck View Post
    Yes and no.

    http://specsandcodes.typepad.com/the...struction.html

    Go down to "Gypsum Board Myths" (the yes part for your first part)

    Then to "Conclusion" (the no part for your last part)
    Sorry, I don't see the "no" part in the conclusion.

    Thom Huggett, PE, SE, CBO

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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Jerry Peck View Post
    Yes and no.

    http://specsandcodes.typepad.com/the...struction.html

    Go down to "Gypsum Board Myths" (the yes part for your first part)

    Then to "Conclusion" (the no part for your last part)
    Quote Originally Posted by Thom Huggett View Post
    Sorry, I don't see the "no" part in the conclusion.
    The 'no' part is that it is not 'gypsum board' used for that, but Type X gypsum board, and Type X gypsum board has: (underlining is mine)
    - "Type X gypsum board has a special core that gives 5/8-inch board a 1-hour fire-resistance rating or 1/2-inch board a 3/4-hour fire-resistance rating, when applied parallel to wood studs at 16 inches on center and tested per ASTM E 119, Standard Test Methods for Fire Tests of Building Construction and Materials."

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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Jerry Peck View Post
    The 'no' part is that it is not 'gypsum board' used for that, but Type X gypsum board, and Type X gypsum board has: (underlining is mine)
    - "Type X gypsum board has a special core that gives 5/8-inch board a 1-hour fire-resistance rating or 1/2-inch board a 3/4-hour fire-resistance rating, when applied parallel to wood studs at 16 inches on center and tested per ASTM E 119, Standard Test Methods for Fire Tests of Building Construction and Materials."
    Actually, I disagree. Even non-Type 'x' gypsum board is considered non-combustible under the IBC as it meets the criteria of Section 703.5.2.

    By the way, your link has a typo in the first sentence of paragraph 2 under Myth #1: "In a composite material, the structural base may be covered with a surfacing not more than 1/8-inch (not 5/8) thick which has a flame spread index of not more than 50 when tested per ASTM E 84...." (Bold italics mine)

    By the way, I appreciate that you are a code reader.

    Thom Huggett, PE, SE, CBO

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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Thom Huggett View Post
    Actually, I disagree. Even non-Type 'x' gypsum board is considered non-combustible under the IBC as it meets the criteria of Section 703.5.2.
    Not disagreeing that non-Type X gypsum board is considered by the code to be non-combustible, only stating that the same code requires Type X gypsum board to be used for fire-protection in rated assemblies, not 'regular' gypsum board.

    That is what that 'Conclusion' was stating.

    [quote]By the way, your link has a typo in the first sentence of paragraph 2 under Myth #1: "In a composite material, the structural base may be covered with a surfacing not more than 1/8-inch (not 5/8) thick which has a flame spread index of not more than 50 when tested per ASTM E 84...." (Bold italics mine)

    I noticed that too, but we all make typos which are not caught by us or others until after publishing something - I really dislike doing that, but it happens occasionally.

    By the way, I appreciate that you are a code reader.
    That's part of 'my yob' (intentional, as differentiated from the 'that's not my yob' expression).

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    Default Re: Requirements for masonry chimney attic fire block

    Quote Originally Posted by Thom Huggett View Post
    Mark,

    According to IBC Section 703.5 gypsum board is a non-combustible material. The core meets ASTM E-136 and the facing is less than 1/8" with a flame spread less than 50 according to ASTM E-84 (see IBC Section 703.5.2). I agree that it does burn, but the IBC does consider it non-combustible. That's why they cover the walls with it in Type I buildings (IBC Chapter 6).
    I think that the confusion relates to the intended use of the material. In fire-rated construction the intent is to minimize the spread of fire. However, when placing a material adjacent to a potentially hot surface the goal is to prevent combustion from occurring. Here are two explanations why I say that it should not be used:

    State of New Jersey
    Department of Community Affairs
    Division of Codes and Standards
    PO Box 802
    Trenton, New Jersey 08625-0802
    Richard J. Codey
    Acting Governor
    Charles A. Richman
    Acting Commissioner
    Date: December 1990
    Revised: December 2005
    Subject: Gypsum Wallboard
    Classification
    Reference: N.J.A.C. 5:23-3.14, Building
    Subcode, Section 703.4.2
    N.J.A.C. 5:23-3.20,
    Mechanical Subcode,
    Chapter 2
    Page 1 of 1
    90-3
    It has recently come to the attention of the Department of Community Affairs
    that gypsum wallboard is something being mistakenly considered a noncombustible
    material when applying the clearance-to-combustibles requirements of the Mechanical
    Subcode.
    The definition of “noncombustible” in the Mechanical Subcode differs from
    the definition in the Building Subcode. The Building Subcode’s Section 703.4.2,
    Composite Materials, states that a material having a structural base of noncombustible
    material (meeting ASTM E136), with a combustible surface not more than 0.125-
    inch thick, and having a flame-spread rating not greater than 50 (when tested in
    accordance with ASTM E84) is acceptable as a noncombustible material. Because
    the Building Subcode allows such “composite” materials, gypsum wallboard can be
    considered noncombustible as defined by the Building Subcode.
    The Mechanical Subcode does not contain such a provision for composite
    materials. Noncombustible materials in the context of the Mechanical Subcode are
    those materials which pass ASTM E136. Gypsum board, because of its combustible
    facing, will not pass ASTM E136. (The only exception to this applies to Type I
    commercial kitchen hoods at Section 507.9 of the Mechanical Subcode.)
    The difference in standards is due to the different purposes of the two
    subcodes. The Building Subcode is concerned with the performance of a material
    under the conditions during a fire, while the Mechanical Subcode is concerned with
    performance during exposure to a constant high-heat source.
    Therefore remember, under the Mechanical Subcode, gypsum wallboard is
    classified as a combustible material.

    Case Studies
    In the National Fire Protection Association���NFPA 101 Code for Safety to Life from Fire in Buildings and Structures, a noncombustible material is defined as a material that, "in the form in which it is used and under the conditions anticipated, will not aid combustion or add appreciable heat to an ambient fire." Materials are tested for noncombustibility in ASTM E 136 Standard Test Method for Behavior of Materials in a Vertical Tube Furnace at 750? C. The test exposes small samples of the material to a stream of air heated to 750? C, (1382? F). The material is deemed noncombustible if:

    • 1) Sample temperatures at no time exceed 780? C, (1436? F).2) There is no flaming after 30 seconds. 3) Once the sample loses 50% of its weight, there is no flaming and sample temperatures never exceed 750? C, (1382? F). ASTM E 136 is an extremely strict test and under its criterion, few building materials qualify as noncombustible. Two USG Interiors products which do are CERAMIC HERITAGE and most THERMAFIBER insulation products.

    In regard to gypsum wallboard, the product's paper facing prevents it from passing ASTM E 136. However, because it does have a demonstrated ability to perform in fire rated assemblies, the NFPA has placed it in a special classification called limited-combustible This category distinguishes gypsum wallboard from other, more highly combustible products. To qualify as limited-combustible, a material must have a noncombustible structural base or core, a surface less than 1/8 in. (0.3 cm) thickness and a flame-spread rating of 50 or less.This last requirement can be confusing because the three national model building codes, (ICBO's Uniform Building Code, SBCCI's Standard Building Code and BOCA's National Building Code), all allow composite materials that meet the NFPA���definition of limited-combustible, to be classified as noncombustible.
    http://www.usg.com/design_solutions/...ustibility.asp


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    Default Re: Requirements for masonry chimney attic fire block

    Good information, Mark, and, because each of the two codes addresses it differently, the most restrictive shall apply when required by both codes.

    The reasoning given for the Mechanical code difference is excellent as fire-resistance rated assemblies are intended to perform one-time ... during a fire ... then get replaced, while the Mechanical code is addressing something being placed next to a heated item day-in and day-out, day-after-day, week-after-week, year-after-year.

    Makes absolute sense.

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    Default Re: Requirements for masonry chimney attic fire block

    Thank you Mark.
    Much appreciated.

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