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  1. #1
    Join Date
    Jun 2014
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    Default rim joist insulation in a ballon framed house...

    Our c. 1875 Italianate is balloon framed. What would be the rim joist spaces between the floor joists in the basement are filled with brick and mortar in some places, and in others (where plumbing or electrical was run) the brick and mortar was removed. I assume one of the reasons for the brick and mortar may have been as a fire prevention step. However, my question is about insulation of this space. Should I leave the brick and mortar in place? Where it was removed, what is the best method of insulation? I have seen suggestions of using EPS foam cut to shape and foamed into place, but is that the best method given the balloon framing?

    I should mention here that somewhere in the past the walls were blown full of cellulose insulation, which is falling out of the spaces where the brick was removed.

    Thanks for reading this and making suggestions.

  2. #2
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    Sep 2012
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    Boston
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    Default Re: rim joist insulation in a ballon framed house...

    any bricks that were removed should be filled with fire blocking insulation such as Roxul Fire Blocking Insulation. there's really no big reason to remove the bricks but if you do or any space where the bricks are missing has to be filled with a fire blocking material. be very wary of the products advertised as "fire blocking foam insulation" as some of them are not able to prevent even a small fire.

    this past fall while doing a remodel job we had to fire block around all recessed lights with 5/8" sheetrock and seal up the seams with a fire blocking material. i forget which one i purchased but when the building inspector showed up for our insulation inspection he asked me which product i used. i showed him the can and he said "come with me, i have something to show you". we went out to the driveway, he sprayed some foam on the driveway, waited about a minute for it to expand then lit it with a match and it burned with a pretty big flame down to nothing. obviously it didn't do what it was advertised to do so be careful.

    fire blocking is very very important. watch this video of a fire that started in the basement in boston this year. this is what fire blocking is meant to prevent regarding fires spreading between the different levels of a house.

    https://www.youtube.com/watch?v=zxEyKEWKmsM

  3. #3
    Join Date
    Jun 2014
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    Default Re: rim joist insulation in a ballon framed house...

    Thank you for your reply. So, help me figure out the right process. First, I fill the cavity in the wall with the Roxul Fire resistant insulation. Then can I seal it with the XPS and foam the edges? Does the XPS and foam provide the necessary vapor barrier? In the areas where the brick and mortar are intact, I should leave it alone?

    Thanks!

  4. #4
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    Default Re: rim joist insulation in a ballon framed house...

    with the Roxul, you just cut the piece to slightly larger than you need and stuff it in the space. you do not need any foam insulation. there is no need for a vapor barrier. the brick and mortar can be left alone as long as it's all intact. if there's a brick missing, just put the Roxul in it's place. it's a very heavy, dense insulation compared to fiberglass. it's an excellent insulator and rodents don't like to eat through it or nest in it.

  5. #5
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    Jun 2014
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    Default Re: rim joist insulation in a ballon framed house...

    Thank you very much for you assistance!

  6. #6
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    May 2008
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    Default Re: rim joist insulation in a ballon framed house...

    Quote Originally Posted by MLB Construction View Post
    i showed him the can and he said "come with me, i have something to show you". we went out to the driveway, he sprayed some foam on the driveway, waited about a minute for it to expand then lit it with a match and it burned with a pretty big flame down to nothing. obviously it didn't do what it was advertised to do so be careful
    I have to wonder how it would burn a week or a month later. A minute or two might not result in full cure, and there could easily be volatile/flammable compounds still present, especially any propellants that might be used. Perhaps the label on the can said something like "requires X days of curing before fire protection is effective"?
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  7. #7
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    Sep 2012
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    Default Re: rim joist insulation in a ballon framed house...

    i read the can, didn't say anything like that.....he's the building inspector, can't argue with him. i was surprised, i think the brand was DAP but i'm not sure. i'll find out what it was and post what i used and what it said.

  8. #8
    Join Date
    May 2008
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    Default Re: rim joist insulation in a ballon framed house...

    The product page for DAP Fireblock Foam Polyurethane Sealant describes it as being used to "Quickly fill and seal large gaps around vents, pipes, ducts and wires; and at wall-to-floor or ceiling-to-floor joints. For use in Type V residential construction, the foam is bright orange for easy code identification and expands 2-1/2 to 3 times its dispensed size. Just one can of this expanding foam yields up to fifteen large caulk tubes."


    However, there is a tech note which states:
    "Product is EXTREMELY FLAMMABLE WHEN DISPENSING! Vapor may ignite explosively. Keep away from heat, sparks and flame. Do not smoke. Extinguish all flames and pilot lights. Turn off stoves, heaters, electrical motors, and other sources of ignition during use and until vapor is gone. Do not puncture, strike or incinerate can. Do not expose to heat or store above 120F. Do not place in hot water or near radiators, stoves or other sources of heat. Do not keep can in direct sunlight or high temperature areas, such as automobiles. If exposed to heat or direct sunlight, container may explode. Store in a cool dry place. Use only as directed. This product is combustible and may constitute a fire hazard if improperly used. DO NOT USE NEAR OPEN FLAME. Cured foam may be combustible if exposed to flame or temperatures above 240F. If burned, cured foam may release hazardous decomposition products."

    It also indicates that it takes 12-24 hours to fully cure. Seems to me that 240F is mighty cool for a fire.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  9. #9
    Join Date
    Oct 2012
    Location
    Houston, TX
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    308

    Default Re: rim joist insulation in a ballon framed house...

    Quote Originally Posted by Fencepost View Post

    It also indicates that it takes 12-24 hours to fully cure. Seems to me that 240F is mighty cool for a fire.
    Or just a little warmer than boiling water. Paper burns at 452, I assume wood at the same.
    It's this old house, not this built after your dad was born house.

  10. #10
    Join Date
    Jan 2008
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    2,203

    Default Re: rim joist insulation in a ballon framed house...

    A fully-engaged house fire will be around 1200 degrees at it's core and few products can withstand those tem,temperatures for long. Even if they do, whatever supports them may not. Roxul (aka rock wool, mineral wool) will withstand this and more. If it fits snugly it will mitigate drafts which carry superheated air into new areas, slowing them enough to cool them to safer temps. It's better against wood than brick-concrete-mortar because those materials will always contain moisture which will cause adjacent untreated wood to rot.

    Balloon-framed structures are almost fire-traps so seal the bottom and top openings well and be sure that whatever does that is highly fire resistant to that 1200 degree standard. A fire contained can be controlled, one that is not contained cannot- especially when walls act like chimneys!

    Phil

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