Blown Fiberglass or Cellulose?

[Falcon67]

FWIW, since this thread is back from the dead: I ended up with glass batts because I could budget for it and buy a little at a time. The ceiling is R13, installed after the ceiling was put in so there is not much of a vapor barrier. I am in the process of caulking the gaps in the OSB ceiling because it does leak air. Eventually I'll hose some blown glass over the top. Walls are also R13, regular glass batt.

It's been no problem to hold 960 sq/ft to 80F with 16,500 BTU of AC. In summer, 100F outside would be 85~88 inside the shop after sitting in the sun all day. We recently had our first decent cold front, with night temps in the low 40s, cloudy for three days and nothing above 52 until it moved out. The last morning (Monday) there was frost on all roofs. Without running the heat in the shop, the coldest it got was 64. I would expect it to hold even better once I get all the gaps caulked.

 

[Steevo]

Steevo,I've seen some pics of your shop,I will be doing something similar.What did you use for a ceiling and did you use a vapor barrier?

Ceiling is 5/8 sheet rock, and no vapor barrier above ceiling, just blown-in cellulose on top.
Attic is fully vented, eaves/soffits, gables, ridge vents.

 

[Angelfire]

I just recently installed insulation in my addition and eventually will get to my new detached garage. I decided to go with mineral wool batts. I'm not aware of a blow in mineral wool product out there but it may exist. I found that it was itchy to work with although not nearly as itchy as fiberglass. I went with the wool for a few reasons. 1. It doesn't burn, smolder, (it will eventually but needs to get to like 2500F at which point the rest of the house will be long gone!) etc... 2. Higher R values than fiberglass/cellulose etc... per inch of insulation 3. Doesn't settle at all. The batts are tight woven and I can't see this stuff settling ever. You can literally stand a batt on edge and it'll stand on it's own. 4. Sound. The mineral wool offers pretty good sound control. Sound barriers are typically made of this stuff although those batts are compressed a bit more than their standard insulation. 5. I liked the fact that I could cut openings for boxes, wires etc... and the insulation wrapped around those obstacles easily. 6. With it's density, I felt I'd get better protection against air infiltration.

I haven't been through a season of heating/cooling to determine if it's doing a better job yet but can already tell the difference between my existing house and the addition in terms of heat retention and sound. In my house, it'll drop in temp several degrees through the night with no heating applied. The addition stays within 1 degree of where it started the night before so I'm encouraged that it's working well. Another data point is I can hear vehicles pull up to my house while in the existing structure (fiberglass by the way) yet can't hear them at all in the addition, and it's closer to the driveway, so I'm encouraged that sound control is good too.

Time will tell I suppose. Pricewise, mineral wool is expensive relative to cellulose and fiberglass but I'm hoping for long term return on value for this stuff. The ultimate would be spray foam but that's much more expensive and I decided against it due to that. Another consideration for me is I'm constantly adding circuits etc.. and really didn't feel like opening up a wall or ceiling only to have my insulation come tumbling down. Sorry to take this OT.

 

[dlenkewich]

R Value?
The fiberglass people invented the test. It is in a sealed box where all products test the same but put it in a place that air can pass through then the R value changes. Foam and cellulose both block air and stay the same R value. Fiberglass lets air flow through(think furnace filter) and reduces R value. Could be only 1/3 of the R value.

Thats why we use vapour barrier. Spray foam companies love that "Test" because people don't use their heads.

 

[mx500]

i installed the johnsmansville fiberglass from menards. 1500 sq ft. attic actually had fun doing it. no dust, no itching. stuff flies out like its snowing. dont even think i had long sleeves on. ive been back up there adding wiring for lights and have not had an itch.
doing the same with my home garage soon.

 

[Highbeam]

Nice old thread. I still think there is a lot of old myths about fiberglass. The itchiness is not true anymore with many of the modern blown FG products being itchless.

I am no longer so anti-cellulose though. It really will come down to cost between blown FG or cellulose. It's not about itch, not about bugs, or fire. Just cost. Performance for a given R-value is so close that we can say it is the same.

So cost.

 

[haugy]

Mine was all about weight. My shop manufacturer didn't design the trusses for drywall, so I had to improvise to cut weight. So on my choice it was merely weight. Fiberglass.

 

[JakeKohl]

Nice old thread. I still think there is a lot of old myths about fiberglass. The itchiness is not true anymore with many of the modern blown FG products being itchless.

I am no longer so anti-cellulose though. It really will come down to cost between blown FG or cellulose. It's not about itch, not about bugs, or fire. Just cost. Performance for a given R-value is so close that we can say it is the same.

So cost.

Quotes I received for my 2 story 24x36 garage (including insulating between floors) were $1,800 to $2,200 for fiberglass bats and blown in attic, $2,200 to $2,400 for blown in cellulose. Easy choice. In the last three months I've been heating and cooling my upstairs 100% of the time. My utility bill is averaging $9 more than the previous year over that time span though I'm conditioning an additional space nearly 1/2 again as large as my house. Granted, weather could play a big roll in that

 

[richtersrodz]

On my new constructed house, they blew in the white cellulose. I like to take family upstairs just to show them how fancy my attic is.

http://www.garagejournal.com/forum/album.php?albumid=1594&pictureid=21166

Out of all of the problems I had with building my house, I'm am very impressed with the way they shot in the insulation. It looks like fresh snow, and makes you want to lay down in it. They also shot it all in the walls. On the places where there was not sheetrock yet (see picture), they put up a cheese cloth, and then shot the insulation to the opposite side. It was damp, so it stuck to the cheese cloth, and then they waited a couple of days before coming back to put up the sheetrock, so it could dry. It was packed in there pretty tight.. Very cool technique....

 

[toyotadriver]

On my new constructed house, they blew in the white cellulose. I like to take family upstairs just to show them how fancy my attic is.

http://www.garagejournal.com/forum/album.php?albumid=1594&pictureid=21166

Out of all of the problems I had with building my house, I'm am very impressed with the way they shot in the insulation. It looks like fresh snow, and makes you want to lay down in it. They also shot it all in the walls. On the places where there was not sheetrock yet (see picture), they put up a cheese cloth, and then shot the insulation to the opposite side. It was damp, so it stuck to the cheese cloth, and then they waited a couple of days before coming back to put up the sheetrock, so it could dry. It was packed in there pretty tight.. Very cool technique....

That's fiberglass not cellulose.



I recently priced blow in fiberglass VS blow in cellulose for a future house build. Unless the cubic ft measurements per bag were wrong, cellulose came out a little bit cheaper.

 

[Highbeam]

That's funny, I also looked at the snow white cellulose and thought it sure looks like fiberglass to me but maybe some company has starting bleeching it so it would look better.

Just goes to show you, the FG no longer is nasty stuff.

 

[Delta74]

do folks just not know about Roxul insulation, or is it just discounted and ignored? I love the stuff, its great, mold resistant, sound absorbing, better R value per inch, flame resistant, or is that retardent. Yes its more expensive then fiberglass, weights more too, but its alot cheaper then any blown in set up, check them out, you may be surprised or tell me to F off, but I have used it in my home, and love it, and WILL be using it again without a second thought as to insulation, check out there home site, may be your answer, and btw, its used in alot of the Idustrial buildings I am use to working in, in the oil patch, also used for pipe wrap on the turbines for steam yada yada, its not a new product and has a proven history behind it.

anyway again take a peek may be your answer.

www.Roxul.com

 

[NUTTSGT]

do folks just not know about Roxul insulation, or is it just discounted and ignored? anyway again take a peek may be your answer.

www.Roxul.com

It's something that is not common in this area. There is a local plant that makes blown in cellulose insulation. The area builders can buy it direct and alot of them use it.

Roxul is just something not found around here. The sprayfoam is just starting to come into this area. Contractors are usually old school and don't like change. . . . we've been building houses like this for 40 years. .. . .

 

[Highbeam]

The roxul is available as loose fill insulation. Not blown in but spread by hand. Anybody used it?

 

[jvitez]

I used Roxul batts for the garage walls. I concur: great stuff! Mice don't like to live in it, it's water repellent, R22 vs R20 for a 2x6 stud wall, easy to cut with a bread knife of all things, and much better at customizing for fit around obstacles.

AI just saw Roxul loose fill at Home Depot and Rona. It would be a lot of work to hoist up many bags, shake each out trying not to fall through the ceiling, and then fluff it up. When I do my garage ceiling it will be blown in something for the convenience of installation. I really want to use cellulose, but I might be forced to use fibreglass for the weight saving as I plan on using a metal ceiling.

Interestingly, check out this link to Menards about blown in fibreglass. Look at the bottom.

http://www.menards.com/main/store/2...rod_Tech_Spec/UltraComfort-CovChart3_2_10.pdf

It says "To maintain R-Values at Winter Design Conditions in colder regions, install extra insulation in accordance with this chart." -24F to -28F requires an extra 2.5 inches for R38. Why would you need even MORE fibreglass if you live in a very cold climate? Why doesn't cellulose require that? Because of convection currents within the fibreglass itself!!

Even the fibreglass manufacturer itself acknowledges the reduction in R value at colder temps.

 

[oilslick]

I just finished blowing in my 32x54 with 84 40cuft bags, ended up with at least 8" everywhere and most around 10". The bag said it weighs about 1lb per sq ft at that depth. It cost me about 500 for materials and 3 hours blowing it. I have 2/12ceiling inside a 4/12 roof which made it a tight mother getting out to edges but doable. Sure wish I could have afforded foam!

 

[Highbeam]

It says "To maintain R-Values at Winter Design Conditions in colder regions, install extra insulation in accordance with this chart." -24F to -28F requires an extra 2.5 inches for R38. Why would you need even MORE fibreglass if you live in a very cold climate? Why doesn't cellulose require that? Because of convection currents within the fibreglass itself!!

Even the fibreglass manufacturer itself acknowledges the reduction in R value at colder temps.

Look at that temp! -24f is so cold, and 2.5" so small. Whatever heating system you have will be cranking in any case.

 

[jvitez]

Look at that temp! -24f is so cold, and 2.5" so small. Whatever heating system you have will be cranking in any case.

Point taken, but it gets to -24F almost every winter here, at least for a while. 2.5 inches can be quite a few more bags though.

None of this happens with cellulose. That's the point I'm trying to make.

If you're in a moderate climate, and heat loads are small, a bit of extra heat loss if no big thing. But if you're in a cold climate it certainly can be.

Hoo hoo hoo, hee hee hee, cellulose for me............

 

[KPSquared]

I'm about to do my garage. After all the reading, i still plan to do cellulose. R40 is the minimum for a ceiling here and i may go R50.

I have the area underneath my attic space that I'll have to blow in first and fill up, then i'll get it good and deep in the rest.

Still need to price the whole shebang. Fibreglass is probably cheaper...

$13/bag for cellulose, $26/bag for fibreglass.

Based on charts from each company its about $140 more for cellulose. I wonder which does better shot into the 10" space between the floor and ceiling?

It would seem the cellulose has a significantly higher r value when you have limited space.

10" = R35 vs. R27.

Full 6mil poly vapor barrier taped and sealed with acousti-seal. Only place air gets in this building is when the doors are open...