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  1. #1
    Join Date
    Sep 2009
    Posts
    7

    Default Attic Insulation - Cellulose vs Foam

    Hi -

    This seems to be a popular topic and any further advice would be greatly appreciated as I've researched this to death.

    I recently purchased a home just outside the Boston, MA area (built in 1966) and I want to add insulation to the attic. I've researched cellulose, spray foam, encapsulated and fiberglass a lot and I've narrowed it down to the cellulose and the spray foam.

    I would love to do the foam, but I'm unsure about it's:

    1) long-term affects, in other words, does it degrade in any manner that would be hazardous to my family (toxic fumes in later years?) or does it really lose itís effectiveness over the years? I plan on living here for at least 20 years.

    2) being in my 40s, I'm of the generation that believes that it's not a good idea to completely seal off the attic. I'd be spraying the foam on the envelope of the house, sealing all of the gable vents, ridge vents and soffits, creating conditioned space. Iím doing this as Iím going to install a gas-fired boiler in the basement and run a couple of water/glycol lines up into the attic to get heat into the second-floor living area.

    3) the issue of moisture and mold possibly building up in the attic. All of my bathroom vents are properly hooked into PVC pipes that vent outside of the attic, but being constantly dark and unventilated with the foam installed, should I worry about this?

    4) does foam burn? Might it give off toxic fumes if fire is in the area? All I can think of here is that R.I. nightclub (The Station) that killed 100 people.

    If you feel that any of these are real issues, then I have no problems with blowing in cellulose on the attic floor. Though it will be real dusty up there.


    Thanx in advance for your time!!!
    vf

  2. #2
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Attic Insulation - Cellulose vs Foam

    vinfurnier ....., I'll throw in a couple of cents worth


    1) long-term affects, in other words, does it degrade in any manner that would be hazardous to my family (toxic fumes in later years?) or does it really lose itís effectiveness over the years? I plan on living here for at least 20 years.
    Unlike the controversial Urea-Formaldehyde Foam Insulation ( UFFI ) used in the late 70's - early 80's the modern spray foams don't off gas any volatile fumes after the initial install and cure.
    There are other items within homes that may surprise you that off gas toxic gasses like furniture , carpets, building materials , cabinets , etc , more so than the insulations used .... Google Formaldehyde.

    Spray foam has only been introduced into the residential market within the last 10 years or so ........ however it has been widely used in industrial and commercial applications for years without loss of effectiveness.


    2) being in my 40s, I'm of the generation that believes that it's not a good idea to completely seal off the attic. I'd be spraying the foam on the envelope of the house, sealing all of the gable vents, ridge vents and soffits, creating conditioned space. Iím doing this as Iím going to install a gas-fired boiler in the basement and run a couple of water/glycol lines up into the attic to get heat into the second-floor living area.

    3) the issue of moisture and mold possibly building up in the attic. All of my bathroom vents are properly hooked into PVC pipes that vent outside of the attic, but being constantly dark and unventilated with the foam installed, should I worry about this?
    I'm not quite sure of your layout , perhaps your upper living space is separated from the attic space by a knee wall?

    One thing to consider ...... whenever you take steps to tightly seal a home maintaining the comfort and efficiency ( especially an older home ) you change the dynamics.

    While tightly sealing the home is an important step to conditioning the living space ( heating and cooling ) you are preventing the conditioned air to escape and allowing the outside unconditioned air to enter of your home.

    Leaky or drafty homes allowed the inside humid stale air to escape and fresh air from outside to replace it .... this is known as air exchange ( uncontrolled mind you ) and is important for good indoor air quality. In many instances people that have their leaky homes sealed and well insulated discover increased inside humidity creating mold and mildew issues.

    This is no faulty of the materials used ( since mold requires organic materials to feed and thrive spray foam is inorganic and doesn't provide food for mold. ) but rather the dynamics of allowing air exchange has been altered.

    It becomes more important to controlling the inside relative humidity ( RH ) by using mechanical ventilation like bath and kitchen exhaust fans vented outside to control the increased RH during those seasons the home is closed tight to the elements. Ideally the use of a Heat Recovery Ventilator ( HRV ) will provide an excellent controlled air exchange for the entire home by removing the stale humid inside air and replace it with fresh outside ..... much like the old leaky home did but in a controlled fashion ..... helping to prevent mold and mildew issues.


    4) does foam burn? Might it give off toxic fumes if fire is in the area? All I can think of here is that R.I. nightclub (The Station) that killed 100 people.
    Yes it will .... but like any insulating material they need to covered over with fire rated material like drywall or plaster if in proximity to a living space. However if in an attic space this usually not considered living space so generally insulation can remain exposed as long a fire rated material separates the attic and living space.
    Besides ..... as another member jkirk said in another thread ...... if a fire has reached the attic then your home is probably toast by then.
    Another point if there were a fire within your home you would likely be exposed to more toxic fumes from the items within the living space like ..... plastics ( even the plastic case of your smoke detectors ) , carpet, furniture, TV , computers , etc..


    Spray foam is an excellent product for sealing and insulating a home if applied properly and if you can afford it.


    Hopefully this helps.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  3. #3
    Join Date
    Sep 2009
    Posts
    7

    Default Re: Attic Insulation - Cellulose vs Foam

    canuk -

    Thanx for all your information regarding this!!!

    The big topic that you covered (which no one mentioned to me - hard to believe as I brought in 5 companies to do estimates on this foam insulation) was the HRV. That makes my decision to do foam much easier as I couldn't figure out how to get fresh air into the attic area.

    Thanx again!!!
    vf

  4. #4
    Join Date
    Mar 2008
    Location
    Mobile, AL
    Posts
    2

    Default Re: Attic Insulation - Cellulose vs Foam

    I too have looked closely at sealing off my attic with foam. The product being marketed in my area is called icynene. The sales pitch sounds good. In fact it sounds too good. I can't help but feel that there's something I'm not seeing. My main concern is the longevity of my roof shingles. I have recently installed a new 30 yr roof and I'm concerned about foaming the underneath of the decking between the rafters. Will the foam shorten or improve the life of the shingles? The sales guys say improve because the heat will be lower in the sealed attic. Also, in five or ten years, if I were to develop a leak in the shingles, how would I know it if the foam prevents the water from being detected?

    I really want to try the foam but I'm hesitant because of these questions. Any advice?
    Last edited by kevin1001; 09-30-2009 at 11:13 PM.

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