Loose fill insulation
Last Post 19 Feb 2009 04:05 PM by jongig. 15 Replies.
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imerUser is Offline
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16 Jan 2009 08:55 AM
My house is a slab on grade two floor wood frame with aluminium siding. Heating system is two zone hot water baseboard. Airconditioning is a central system with each floor having its own unit.
I am looking for ideas for reinsulating the attic and possibly the walls.
Few months a go i saw in my neighborhood they  were reisulating an attic with loose fill insulation. Is this a good idea or are there better options?
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16 Jan 2009 09:50 AM
For the attic the easiest, cheapest is to blow in fiberglass. You can even rent the machine and do it yourself. But be careful not to plug the ventilation, you may have to add chutes that keep ventilation coming from your eves.

The walls are much harder, what kind of insulation are in your walls now?
Brad Kvanbek - ICFconstruction.net
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16 Jan 2009 10:29 AM
As a member of this "Green" site, I would have to argue the use of fiberglass in the attic.  I would recommend the use of blown-in cellulose instead.  The cellulose is made of recycled paper products, which fits the Green mentality much better than fiberglass.  It may settle slightly, so install it at a little greater depth than the ultimate goal. 

Cellulose insulation has much finer fibers than fiberglass, and when it is blown or densed packed into walls and ceilings, it becomes almost liquid, flowing into cavities and around pipes to completely fill the walls and seal every crack.  Fiberglass can not duplicate this action because of the density of the fibers.  Foam can do the same thing, but it is much more expensive.

All recycled cellulose is fire retardant treated.  Additionally, becuase of the density of cellulose, it actually inhibits air movement much more than fiberglass, thus slowing any fire spread from room to room because the fire has difficulty penetrating the insulation.

The insulatiing perfromance of cellulose is also greater than fiberglass.  At R 3.6 to 3.8 per inch, for cellulose, vs. an  R-value of about 2.2 to 2.6 for fiberglass. But R-value is only one factor in the energy efficiency of a home. Studies of actual buildings regularly show that cellulose-insulated buildings may use 20% to 40% less energy than buildings with fiberglass, even if the R-value of the insulation in the walls and ceilings is identical. One of these reasons is the same reason cellulose retards fire better, because air can not move through it.

It takes less energy to make the paper product than to make fiberglass.  It is a better insulator.  It is a better fire retarder.  It recycles already existing paper products instead of sending them to the landfill.  My recommendation would be cellulose insulation!

Steve
www.mdconstructionllc.com
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16 Jan 2009 11:57 AM
Posted By Greenbuild1 on 01/16/2009 10:29 AM
As a member of this "Green" site, I would have to argue the use of fiberglass in the attic. ...The insulatiing perfromance of cellulose is also greater than fiberglass.  At R 3.6 to 3.8 per inch, for cellulose, vs. an  R-value of about 2.2 to 2.6 for fiberglass.

Personally, I'm a 'Foam' person, but fiberglass does have it's place, and the numbers that you quoted for fiberglass are incorrect. A 3.5" - R-13 batt has an R-Value of 3.7 per inch, and a 'High-Density' 3.5" - R-15 batt has an R-Value of 4.29 per inch. And, if you've ever used 'High-Density' batts, you'll understand that not much air can penetrate through them.

But then again, I'd prefer foam...
....jc<br>If you're not building with OSB SIPS(or ICF's), why are you building?
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17 Jan 2009 10:28 AM
Another vote for blown-in cellulose.
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17 Jan 2009 04:15 PM

Just went thru this decision making process when we built our new ranch house.  I really do like the idea of going green and saving money at the same time.  We installed a Arxx  basement which I really like and we also have geothermal heat (Which is working great even in the cold snape we have had the last 4-5 days)  We had 12 inches of cellouse blown into our ceilings.  I think the blown in cellouse is the way to go especially if you want to go "green".

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17 Jan 2009 04:30 PM
cellulose in my attic r50
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18 Jan 2009 10:58 AM
Greenbuild1,

For the most part I agree and initially cellulose has a better r-value per inch, but what is the r-value after it settles? Fiberglass is better if it gets wet.

But where you are clearly wrong is when you stated, "[cellulose]is a better fire retarder". Fiberglass will not burn and it melts at 1800 degrees, I have some touching my single wall chimney at my wood stove. Cellulose burns very well, I have seen it many times. The fire retardant is a powder added during the shredding process and may not get distributed properly, so in a fire the un/under treated cellulose burns and spreads the fire through the attic.

Don't get me wrong, I do not recommend against the use of cellulose, but I prefer fiberglass.

Brad Kvanbek - ICFconstruction.net
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18 Jan 2009 11:32 AM
Another vote for blown cellulose here. Just consider the loading on the ceiling if you are going over 12" deep. Standard 1/2" wall sheetrock attached to trusses 24" oc may not be sufficient to carry the load. 5/8" sheetrock or specifically designed ceiling board may be necessary.
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18 Jan 2009 01:35 PM
Regular 1/2" drywall cannot be be installed on 24" centers. 5/8" or 1/2" ceiling drywall must be used.
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18 Jan 2009 08:55 PM
Posted By ICFconstruction on 01/18/2009 1:35 PM
Regular 1/2" drywall cannot be be installed on 24" centers. 5/8" or 1/2" ceiling drywall must be used.
1/2" drywall can and is used on ceilings 24" oc all the time around here, especially on spec homes.

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19 Jan 2009 07:26 AM
It must be the stronger 1/2" ceiling rock?
Brad Kvanbek - ICFconstruction.net
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20 Jan 2009 06:07 PM
Posted By ICFconstruction on 01/18/2009 10:58 AM
Greenbuild1,

For the most part I agree and initially cellulose has a better r-value per inch, but what is the r-value after it settles? Fiberglass is better if it gets wet.

But where you are clearly wrong is when you stated, "[cellulose]is a better fire retarder". Fiberglass will not burn and it melts at 1800 degrees, I have some touching my single wall chimney at my wood stove. Cellulose burns very well, I have seen it many times. The fire retardant is a powder added during the shredding process and may not get distributed properly, so in a fire the un/under treated cellulose burns and spreads the fire through the attic.

Don't get me wrong, I do not recommend against the use of cellulose, but I prefer fiberglass.


How if fiberglass better when wet?  Fiberglass  may dry quicker if it get's saturated, but it's insulation value is then permanently compromised.   And in loose fill applicationa (as opposed to dense packed in walls) it LOSES R VALUE at bigger temperature differences (just when you need it the most, it's doing the least.)  Conversely, loose filled cellulose GAINS R value slightly as the temperature difference increases.

If you blow it to an R-value at the "settled depth", it's initial R value will be somewhat higher (20% higher if they really fluff the heck out of it, but I wouldn't recommend that- air current through soffit vents will move it around on you if you do.)  Most of the specified R-ratings for cellulose written on the bag are the settled valued for a certain weight of material over a specified floor area.  As long as you do the math and be sure to use the right amount of material, that's the R value in 10 years- it'll be higher the first few.

Loose fill blown cellulose inhibits air infiltration better than loose fill blown fiberglass too (again, not dense-packed, or "cathedral ceiling" batts, which are the best grades of fiberglass.)

Cellulose is usually the value- leader in this application.  Foams form perfect air-barriers, etc. but in open areas where you can heap it deep it's hard to rationalize the cost adder.
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20 Jan 2009 08:46 PM
Fiberglass once dry is the same consistency and as good as it was before it got wet. Cellulose dries crusty and compressed and needs to be replaced, just what got wet.

Cellulose is cheaper per r-value.
Brad Kvanbek - ICFconstruction.net
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20 Jan 2009 10:57 PM
Posted By ICFconstruction on 01/19/2009 7:26 AM
It must be the stronger 1/2" ceiling rock?

The point I was trying to make is that if you are adding attic insulation, particularly blown cellulose which can be rather heavy, make sure the ceiling can handle the extra load.

In the area where I live, there are no building code requirements or associated inspections, so many builders will try to get by as cheaply as possible and will often use standard 1/2" drywall on 24" oc roof trusses on the ceiling to save a buck or two per sheet.  If fiberglass insulation is used as the attic insulation, it can probably handle it without sagging.  But if the homeowner then comes in and blows an additional 6" or a foot of cellulose on top of the existing insulation they may end up with problems down the road.
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19 Feb 2009 04:05 PM
If your attic has fiberglass insulation at r-30 can you blow in cellulose? I had a thought that I would do this because I have an uneven attic floor because of tray ceilings and I think if I blow in insulation it will be better than what I have. Can you blow in over the fiberglass?

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