? Blown In Cellulose or Fiberglass Insulation

chipster_2007March 21, 2008

I need to insulate my house built in 1930's. There is no insulation in the walls and 30 yrs ago, fiberglass batts were installed in the floor of the attic. Not all the bays were insulated and right now I can't tell which one's were not. Of the ones I can check, it looks like the fiberglass batts have settled, there is a space before reaching the top of the bay and they don't seem to fit as snuggly as they did when they were first installed. It has been suggested that I use fiberglass blown in insulation over cellulose because it won't settle. Are there any other benefits to blown in fiberglass over cellulose? I am told the R value is the same for both fiberglass and cellulose. Is that correct? I have some info of a certain company that says blown in cellulose insulation has a higher R value than fiberglass. Talk about confusion!!! I have also heard that the boric acid in the cellulose insul eventually breaks down and becomes ineffective. Also the floor boards in the attic have spaces and cracks between them so I am concerned re blowing in any type of insulation and having the fibers wind up in the air that we breath. Would the use of tyvek underneath the floor boards be at all helpful in preventing this? Heating bills are HIGH. Would appreciate any imput. Thanks

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I had fiberglass blown into the attic over the cellulose. If the cellulose ever gets wet it will need to be removed. Good luck trying to find someone to remove that stuff.

Also, fiberglass is guaranteed never to catch fire. I'm not sure cellulose can say the same.

As far as settling , both products will settle overtime. I chose a contractor that guaranteed the product and would come back and re-blow if it fell below the 18" mark.


    Bookmark   March 21, 2008 at 2:38PM
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chipster 2007,
Cellulose and fiberglass are both non flamable to my knowledge. It is true that cellulose has a higher R value than fiberglass and it is also cheaper.
I do blown in cellulose from time to time for the company I work for and can tell you that people are very suprised how quiet their house becomes by the time we are finished.
Our average installed price ranges from a low 1.20 per SF to 2.20 per SF depending on outside conditions. For example, vinyl siding is the easiest to pop open on the outside and drill holes behind the siding to fill in between the studs, Aluminum harder, and Brick must be done from the inside.
I hope this bit of info sheds some light on your project.

All the Best,

The Porch Guy

Here is a link that might be useful: My Album

    Bookmark   March 21, 2008 at 9:43PM
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Hi Porch guy, I looked at your album and you do some Very Nice Work. What would be your recommendations for dealing with an attic floor that is only partially insulated with fiberglass batts that are now settled and not filling the bays fully? Looking at your work, I would like your opinion. Thanks

    Bookmark   March 22, 2008 at 1:45PM
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We had cellulose blown in our walls just last Monday. Porchguy is right, the house is quieter and just feels tighter. Obviously it's too soon to know how much lower our gas bill will be, but I can tell you that the boiler definitely kicks on less often than before. Also, the bedrooms that were colder before now feel the same temperature as the rest of the house.

I just looked at the bill and we paid $1.20/sf for the installation. Our house was built in 1957 and has cedar siding. Besides the outside walls, he also insulated the walls in the stairwell up to the attic, since these walls face living areas on the other side.

    Bookmark   March 22, 2008 at 5:29PM
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Ver nice work porchguy!

I use cellulose as it conforms better to odd shapes. Plus it's denser than fg, so it performs better as a air barrier. In cold climates, fg in an attic loses up to half its nominal R value.

Here is a link that might be useful: cellulose vs. fiberglass

    Bookmark   March 22, 2008 at 5:37PM
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I also vote for fiberglass in your situation. Also make sure you have enough ventillation so you don't end up with moisture problems. Roof vents typically do the trick.

    Bookmark   March 22, 2008 at 7:53PM
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chipster 2007,
Removal of old settled fiberglass batts is a dangerous job and removal crew must be equipted with jumpsuits and breathing apparatus. Additionally the fine glass particals become airborne and drift everywhere. Especially if you have an A/C uint up there, chances are these particles could get into the system.
Leaving them as they lay and blowing right over them is the safest method and does not jepordize the effectiveness of the job.
Over the years we rarely remove batt fiberglass as it not necessary but if the homeowner wants them removed, there is an additional charge.
My advise is to leave the batt insulation where it lay and just blow over them - you'll get the same results.

All the best,

The Porch Guy

    Bookmark   March 23, 2008 at 9:11AM
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Another consideration is that cellulose insulation is better for the environment than fiberglass:

    Bookmark   March 24, 2008 at 1:22AM
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jcin los angeles,
Thank you for such a valuable link.

All the Best,
The PorchGuy

Here is a link that might be useful: My Album

    Bookmark   March 24, 2008 at 6:50AM
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I blew cellulose (recycled newspaper) into my 900sf attic. Lowered heating costs and kept the house much cooler in summer (I live in LA). the city or state had some sort of rebate program that made the total cost about $350.

no brainer.

    Bookmark   April 22, 2008 at 5:00AM
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We have a 1930s brick so insulation was blown from inside the house. We too immediately noticed less noise and a 'tighter' feel to the house. The company plugged the holes and hubby easily patched them although the plaster is not exact but only noticeable if you are looking for it. We are very pleased and noticed an immediate reduction in our heating bill.

    Bookmark   April 22, 2008 at 5:31PM
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Thanks for all your helpful info. I have also been considering having the fiberglass batts removed in the attic and having the new "green" closed cell foam blown into the attic only and later having cellulose put into the walls. I live in the NE and the recommended R value in the attic should be 39-39. The depth of the bays are only 6 in so in order to obtain anything close to that, I would have to use some type of foam. Appreciate any ideas and is anyone familiar with the "green" foam. Thanks

    Bookmark   April 29, 2008 at 11:55AM
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We generally heat the outside in the winter and considering I just paid $463 for 100 gallons, we need to do something fast. Our house is 140 years old and I think the blown in is the way to go for us! Our house is 1100 sq ft, 1 and 1/2 stories. Last year I did not have to turn the heat on upstairs, it gets so warm. Down stairs is beyond drafty. We need to batt the basement and blow in the walls.

I hope we can do it! We are planning on purchasing a wood pellet stove too! Anything to avoid paying a million dollars to heat this old place!

    Bookmark   July 23, 2008 at 8:46PM
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We are in a 1930's Colonial in Texas. Our A/C bills were astronomical this summer and that was with them programmed and not even being that comfortable in the house. Now it's getting chilly and I am about to get the house insulated. There is hardly any insulation in the attic so that should be a big help, I hope. My question is about insulating in the walls. I have heard that a lot of old homes have "firebreaks" or something like that which is a board laid horizontally in the wall (which doesn't help for a fire at all, obviously) and that you have to drill every 18 inches or so around the room on the top, middle and bottom. Is this true? Any more info on this? Thank you!

    Bookmark   November 23, 2008 at 6:17PM
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I have the same question. We have a turn of the century house with wood siding, cypress they tell me, but I do know from inside work there are the horizontal boards in the walls.

Also, Do you insultate crawlspace? We have about 12" between floors. Could you blow insulation there as well?

Porchguy, that is some wonderful work - enjoyed the pictures very much.

    Bookmark   November 28, 2008 at 10:52AM
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We had our crawl space area ,basement sills,2 weeks ag. Made with soy-bean oil. You can't believe how much less furnace has run allready this year.Guy who own company friend of a friend only cost me $255.

    Bookmark   November 30, 2008 at 8:31PM
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Just had the insulation done yesterday in the attic. The insulation guys (as well as I) could easily see that there was virtually no insulation in the attic--as in NO "R" factor, whatsoever. We had 19 inches blown in although I don't know if it was cellulose or fiberglass. It is white, looks kind of like that packing material "peanuts", though not hard like that. I have already noticed a BIG difference in how much warmer it is and how much less the furnace is coming on. I thought I would see how this goes and then if we have to do the walls, we will. I am curious as to whether anyone has any photos of what it looks like when they do this to your walls, as in how many holes there are, how big, etc. Our walls are drywall, I am guessing (though not totally sure), and the texture is something that would be hard to replicate if we were to patch it so I am wondering exactly how intrusive this would be.

    Bookmark   December 3, 2008 at 3:24PM
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I just had fiberglass blown in the walls - from the outside of the house. They drilled 2-1/2inch holes in each bay at the bottom and top of each floor - I'm not sure if they do the same from the inside but I suspect so. They plugged each hole with a tapered wood plug pounded in place.

    Bookmark   December 5, 2008 at 12:57PM
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Handel27 please list who did your job

( sf valley)

    Bookmark   April 13, 2011 at 5:58AM
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Spida, sorry, but you're not too likely to get a reply, and it might not be worth anything if you did. Handel27 posted that note about 3 years ago.

    Bookmark   April 13, 2011 at 8:15PM
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