Topping up Attic Insulation: Blown Fiberglass or Cellulose?

[velvetfoot]

I'll add that a co-worker, who's selling his house, told me his 9 year old prefabbed house that was shipped in sections from PA, has 12" of loose fill rock wool in it.

I know you can buy batts in Canada-not sure about blown.

 

[allhandsworking]

I had blown in fiberglass placed above the old R-9 batts in my attic about a year and a half ago. The nicer blown in FG doesn't itch and is much less dusty than I remember the cellulose being. It's white too. I chose FG because cellulose is food for lots of animals, food for fire, and seems like somebody's grand idea to recycle more than an innovation. It is also heavier and settles more than FG. My old sheetrock doesn't need more weight on it. FG and cellulose are the same R value per inch so no benefit there.

I couldn't see any reason to use cellulose but plenty reasons not to.

I spent lots of time before the blow in going around and sealing all penetrations and installing baffles along the eaves to prevent blocking the ventilation. The old FG batts are super itchy. Your old FG batts include the Vapor barrier so the only benefit I've heard of for cellulose, better air sealing, doesn't matter.

Be sure to take the time and seal the air gaps around likght boxes, wire penetrations, plumbing penetrations etc. Also, after the blowing, go up there and be sure that they didn't fill your insulation guard around the chimney with insulation. Even though it won't burn like cellullose, you want that clearance to combustibles.

Cellulose is treated with boric acid! No bugs! Treated with fire resistant cemicals. Aim blow torch at hand with 2" of cellulose No burn!

 

[allhandsworking]

I may be wrong but from my experience as a NYC Fire Fighter I have done lots of overhauling inside burned homes and buildings. Fiber glass inside bays are usually burned up or melted! Cellulose is usually intact. Wood studs are usually not alligatored or charred! So it seems like a good fire-stop! I am not an expert on the material or the instillation.

 

[velvetfoot]

The estimator for the last company just left.
$850/R38/1000 ft2/Blown fiberglass to Owens-Corning's specs. December timeframe.
The proof is always in the pudding, but a grand less!
I'd heard there could be wide variations but that's crazy.

 

[Highbeam]

You'll love it

My soda pop is treated with phosphoric acid and citric acid, bugs love it.

 

[CJRages]

Lowe's offered a great deal on blown in attic fiberglass insulation in October. The Owens Corning Atticat delivery system is free to rent for one day as long as you purchase the required number of bags of insulation - otherwise $20 for a day.

The promotion was: spend at least $400 on insulation and receive a $100 Lowe's gift card. I bought just enough to get over $400. The stuff is 30% tax credit eligible also. I'm not sure if they are still offering this, but you should check into it. It was an fairly easy install. I received approx. 1400 square feet of R 20.

It was an nice process. I was in the attic controlling the spread of the pink fluffy stuff. My friend outside fed into the machine the compressed chunks of fiberglass. This fiberglass did not have the irritating scratchy property of the fiberglass batts. The insulation was softer and very fluffy - like a snow shower when it came out the hose in the attic. Make sure you wear a face mask for breathing up there though. Otherwise a very clean, quick process.

EDIT: I've been looking online - I think the promotion from Lowe's is over. It's still an inexpensive alternative if you have DIY inclinations.

 

[velvetfoot]

I would if I had any friends.

 

[btuser]

I had the blown-in Fiberglass insulation in my attic when I fist moved in. It was level with the ceiling trusses (6") which only gave me r19! I rolled out non-faced r30 batts perpendicular to the trusses so the cavities are fill with loose insulation and the batts are on top. The combo gives a combined r49. No more ice dams. 900 sqft was around 600 bucks (installed myself) but don't forget the tax credit for insulation is going to cut your bill in 1/2.

The reason r50 is prefered in attics is because of the degradation of insulation in very cold weather. Fiberglass is worse, but after close to 20 years of breathing borate-laced cellulouse the taste/smell of it just pisses me off, making me relive memories of bad times in attics as an apprentice. I DO NOT want that stuff in my house. When it -20 degrees outside the fiberglass is closer to r30, which has about 95% the capacity of r50. Celluose is better, I just hate the stuff.

 

[imiller1974]

My wife and I blew in 50 bags of cellulose last year on Oct. 31 for $340.00. Homedepot had the cellulose for $9.93 a bag. Lowes had it for $8.67 a bag. I had Homedepot price match plus 10%, but the lady running the computer entered the price wrong. She was supposed to enter the Lowes price, and the computer would do the 10% calculation. She did the calculation on her calculator, then entered that price into the computer, so I payed $7.02 a bag, then got an additional 10% by using a Homedepot credit card. She actually caught her mistake, but gave me a wink, and told me to haul ass. The blower rental was free for 24 hours for every 20 bags purchased. It took us about 4 hours taking 3 breaks.

The process isn't too bad for the person in the attic, granted it's not during the summer. We plugged to hose up twice trying to go too fast, but I got the slide valve set right for my wife and she didn't have any more problems. I manned the hose in the attic, and she fed the blower. The attic person has it made. The person feeding the machine has it rough.

I also put in R-19 insulation in the floors that month. Between the attic and floor insulation, it dropped our electric bill about $10 a month. I spent a little under $1000 total...

 

[blujacket]

My wife and I topped our 5" cellulose with R-30 fiberglass batt rolls. Lowe's had it for $9.37 a roll with a $100.00 mail in gift card for $400.00 spent. We used 47 rolls, total was $471.22. After the gift card will be $371.22. Big difference so far. Heat pump runs 1-2 times a day.

 

[NEDLAX]

Fiberglass is safer in the case of a fire yes, but if your house is on fire and its in the attic is there anything to save? lets focus on not letting a fire happen. Cellulose preforms better in the attic than fiberglass.... talk to any energy star or building performance institute (bpi) inspector. I have also seen what cellulose turns into when its twenty years old....powder. I do both applications personally. In my house i have an R60 bottom half blown fiberglass top half cellulose. The main thing is get airsealing done its more important than adding more insulation. Look for contractor that usually does new construction they will have a better price than an insulator that does retrofit work. They shouldnt be that busy not a lot of building happening. my company would blow r30 for $ .60sqft depending on your attic size, room, baffle installed or not. Good luck

Since you're in the business...do you know what ever happened to rock wool?
My old house was at some point in the distant past blown full of it but I never hear of it now.

They still have it, well batts never seen it blown, sometimes its called thermal fiber. I had to use it yesterday for fireblocking between floors. I also used it around my pipe to keep insulation away from shield. Are you sure it was rock wool or vermiculite blown in it?

 

[velvetfoot]

Well, they came and did the job today. It looks pretty good to me. They put in some extra vents as well-mine might have been marginally long enough. Now that I think of it, I'm not sure if they put them up in each bay, but I'd have to mess with the batt they put on top of the hatch cover (and which of course I messed with after they went to look up there) - anyway I thought that was a nice touch. I made a little bit of a deal on how many bags they were going to blow in there (Pink Panther says 19.5 bags for 1000 ft2 R38, not in Minnesota, which specifies more). I stood by and watched and counted 21 bags, but at least 20. They put up the height markers too and that seemed to check out too (forgot now, but around 14" I think). Amazing how quick the actual blowing went - the harder part is the "prep", like other things. I guess it's standard for the pros but the thing is radio controlled, not sure how much info is transferred, but the blower is remotely controlled. I don't know if the guy in the attic actually knows how many bales he's used or how he knows he's gonna hit the target - it didn't seem anyway that the two guys were talking, but I could be wrong.

 

[Highbeam]

Turns out you don't need those baffles on every joist bay. Just like you don't need the bird blocking on every joist bay. Still, I put them on every one because I'm just like that.