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Ready to get blown

Post in 'The Green Room' started by Highbeam, Sep 29, 2010.

  1. Highbeam

    Highbeam Minister of Fire

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    I did a remodel last year to a converted garage that included rigid foam on top of the old sloped garage floor and then a new level slab, new walls, sheetrock, bathroom, etc. It was a 25x25 space. It had old fiberglass batts above the flat ceiling that I was able to keep in place with string during the installation of a new ceiling. So this last weekend I went up and installed baffles in every rafter cavity leading to the enclosed soffit, sealed up every penetration with expanding foam and caulk, and finally built a plywood dam around the attic access hatch about 16" above the sheetrock. The old batts have settled to about 5" deep and the plan is to bring that up to an R-38 with blown in fiberglass. I have several issues with cellulose so don't use it.

    I got a bid for 503$ to add the additional insulation for the 625 SF. When the same company did the same job over the rest of the house they added 11" of fiberglass for a total depth of 16-17". Made a big difference.

    I thought the price was pretty good especially when you take 30% credit from it. Trouble is they are 6 weeks out! I can wait.

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  2. vvvv

    vvvv New Member

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  3. Highbeam

    Highbeam Minister of Fire

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    Because it's crap pook. Even the word cellulose should be enough to make you never want to use it. Those last three letters, OSE, ose is a sugar like sucrose, dextrose, lactose, fructose, etc. I do not want cotton candy in my attic. Sugar burns and is a food source. Then of course it is heavier too.
  4. velvetfoot

    velvetfoot Minister of Fire

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  5. vvvv

    vvvv New Member

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    too late, 15yrs ago i blew in ~ 18" on top of fg batts which filled the voids nicely & has since settled some. i like the settling cause it minimizes airwash thru the looser fg.
  6. allhandsworking

    allhandsworking Feeling the Heat

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    Highbeam I think you are misinformed I'm a NYC firefighter I have been in dozens of structure fire were the only place fire traveled was in bays or pipe chases that didn't have cellulose! After this real world experience I inquired about it for my 100 year old house without any insulation. The contractor held a hand full of this material and aimed a blow torch at it, it did not burn! It is also treated with boric acid, this makes it non palatable for insects he then proceeded to eat some( non toxic)! Ok he was wanting the job! I am not against fiberglass or foam just wanted to point out some facts! Installation was easy clean and quick. We save 50% on or heating bill! Then we installed the wood insert and I said good buy to my oil man!
  7. velvetfoot

    velvetfoot Minister of Fire

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    The guy that blew in the fiberglass said cellulose was dusty to blow and the he would've had to wear more of a mask.

    With either of them though, I sure hope I never have to remove it!
  8. GaryGary

    GaryGary Feeling the Heat

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    Hi,
    One well documented problem with loose fill FG is that is develops convection currents within the insulation that get worse as the temperature goes down. At cold temperatures it can cut the effective R value of FG in half. So, just under the conditions you need it the most, it works half as well as it should.

    This is the full scale NREL test that documents this problem:
    http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/92/920510.html

    and,
    http://www.foam-tech.com/theory/rvaluedrift.htm

    Cellulose does not have this problem, and has a good long track record of performing well.

    Gary
  9. Highbeam

    Highbeam Minister of Fire

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    You do realize that cellulose insulation is just ground up newspaper right? I propose that any type of insulation in those bays would have prevented fire transfer. The cellulose just happened to be the junk that was there acting as a fireblock.

    That contractor was using street tricks on you. Paper burns, cotton candy dissolves in water, bugs eat it. Why bother with adding all these chemicals to ground up paper trying to cover up the shortcomings when fiberglass works so well? I sealed my ceiling penetrations so I am not using the blown in insulation as a vapor barrier.

    Cellulose does of course work, there are times when you have no choice such as when filling existing walls. If given the choice, I will always choose fiberglass.
  10. vvvv

    vvvv New Member

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    & u never retested ur old fridge during humid weather too. seems kinda close minded for an engineer? still, some get the degree so to land the job$= gotta be fire specs on cellulose, somewhere
  11. Highbeam

    Highbeam Minister of Fire

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    Take a flying leap pook. Fire specs for newspaper are based on treatment method, they allegedly spray something on the paper in hopes it won't burn. Some folks have open minds and some have already made a decision.
  12. midwestcoast

    midwestcoast Minister of Fire

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    No skin off my back what you go with & I think you'll be happy with a nice thick blanket of whatever up there, but I also think you're repeating unsubstantiated myths about cellulose. I did my homework on fiberglass & cellulose before doing my attic and found: There's a lot of industry junk-science out there, but a growing consensus that Borate treated cellulose is more protective against fire than fiberglass. Not only does it not burn, but the greater density can smother fires. Why would insurance companies approve cellulose if their testing didn't show it to be fire-proof?
    No evidence that Borate treated cellulose causes problems with bugs.
    Sealing air-leaks is necessary for cellulose or FG to work properly, but it doesn't eliminate convective heat loss through blown fiberglass. The convective current is driven by the temp difference btwn the interior & exterior sides of the insulation. "ORNL researchers have determined that some types of blown-in insulation...permit air movement within the insulation, resulting in natural convection...The researchers confirmed that natural convective heat loss in some loosefill fiberglass insulations can be responsible for as much as half of the heat loss at very low temperatures." http://www.ornl.gov/info/ornlreview/rev25-34/chapter8sb2.htm Unfortunately the effect becomes more significant the colder the exterior temp is. The currents don't develop in cellulose due to greater density.
  13. midwestcoast

    midwestcoast Minister of Fire

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    In Highbeams application, with rigid foam (thickness?) and FG batts (if paper-faced) below it, I'd expect convection within the blown fiberglass to be much reduced or eliminated as there wouldn't be the temp differential to drive it.
  14. allhandsworking

    allhandsworking Feeling the Heat

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    . To each his own I would use Fiberglass in certain applications!
  15. Highbeam

    Highbeam Minister of Fire

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    Actually, the rigid foam is on the floor between two layers of concrete. R-10 2 inches thick.

    It's like this, there are drawbacks to each material (FG and paper) and I consider the paper to be inferior. I choose the synthetic material that is naturally non-burning, non-food, and non biodegradable for an out-of-site application where there could be fire, bugs, and water. If I had the paper in an existing space I would leave it be, I don't think that the drawbacks warrant removal. In some cases, the paper can be superior due to other qualities it has including flowability and the wet spray applications.
  16. vvvv

    vvvv New Member

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    nor the wind required for attic ventilation?
  17. vvvv

    vvvv New Member

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    theoretically, if u laid plastic over existing insulation, blew insulation on plastic, & then covered blown insulation with plastic the added insulation plastic sandwich would keep the insulation below from reaching the dew point ? dependent on r value of sandwich= consult building science .com
  18. Seasoned Oak

    Seasoned Oak Minister of Fire

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    Been insulating houses for 30 years. In my experience cellulose is far superior to fiberglass. Iv seen fiberglass shrink to half is original size after so many years in the walls ,also too many spaces around wire and electrical outlets,and odd sized joist spacings, my as well have nothing in the walls. WHen i tear out previously insulated walls sections its the fiberglass thats failed as you can tell by all the dirt in it from air infiltration,not the cellulose. If you gave me fiberglass for free i would not use it to insulate a house.
  19. Reggie Dunlap

    Reggie Dunlap Feeling the Heat

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    Highbeam-
    I'm a builder in northern Vermont and we use blown cellulose frequently. While it has some drawbacks (settling) it is far superior to fiberglass when properly installed in flat ceilings. It will settle a little over time which is why I don't use it in walls. But in a flat ceiling application it is the best material per dollar spent. Only expanding urethane foam is better than cellulose, but foam is 3-4 times more expensive. We generally blow around 16 inches of cellulose and over a few years it settles out to around 14. It fills every nook and cranny, seals up the can lights, and it's inexpensive. There's a reason most every insulation contractor in the colder parts of the country uses cellulose.

    Fiberglass is a good insulating material but even the most conscientious installer can't eliminate all the little gaps. It shrinks over time and it's nasty to work with.

    As far as fire goes have you ever tried to burn cellulose? I have and whatever retardant they use is pretty effective.
  20. Seasoned Oak

    Seasoned Oak Minister of Fire

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    ==============
    If you blow the walls tight they dont settle. Iv torn out walls that were blown 10-15 years ago and NO settling ZERO.
  21. kenny chaos

    kenny chaos Minister of Fire

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    Hey Pook-
    Wouldn't the number of people with cellulose be directly proportional to the number
    of people who live on fast food? Not pretty, but good insulation.
  22. vvvv

    vvvv New Member

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  23. Highbeam

    Highbeam Minister of Fire

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    Trump and reggie, this isn't the walls and this is blow in fiberglass so it doesn't get cut. The new blown in FG is "itchless" so it feels more like cotton. Cellulose truly does have some benefits. My favorites are the flowability and the resistance to air movement.
  24. GaryGary

    GaryGary Feeling the Heat

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    My favorite cellulose advantage is that it does not lose half its R value under cold conditions -- that seems like an important feature in an insulating material :)

    Gary
  25. Reggie Dunlap

    Reggie Dunlap Feeling the Heat

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    I realize it's not going in your walls and that you are blowing in fiberglass. My point was that cellulose is generally preferred to fiberglass in a flat ceiling application. You compared cellulose to cotton candy, said it's likely to burn, and called it crap. None of which is true.

    It's your house and you are going use the product that you feel is best in that situation. But you're not going to convince anyone who does this work for a living that fiberglass is a better blown-in product than cellulose.

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