Insulation, Radiant and Vapor Barriers - Attic insulation - Cellulose & Fiberglass rolls

Hi everyone,

I'm new to the forums and I searched for a thread similar to my dilemma but couldn't find one, so here goes.

My wife and I bought our first house last May. Recently we had a bad rain storm and I noticed a yellowing stain on my daughter's ceiling, so I crawled up into the attic to investigate. I found the source of the leak and patched it up with some Henry's wet patch on the exterior of the roof where the chimney is.

Anyway, while I was up in the attic I noticed that the only insulation currently up there is some R-7 that looks really old. I also noticed that the previous owner had covered the soffit vents with the insulation.

So here is my plan of action. I've already removed the wet piece of insulation and replaced it with some more R-7 that was left rolled in the attic. I was now going to foam insulate around any electrical junction boxes and associated holes in the framing for wiring and such. I was planning on leaving the R-7 in place and pour in by hand some cellulose up to the height of the joists(around 6 inches). Then I was going to buy some rolls of R-30 and lay them perpindicular over the joists to get an R value of at least 49.

Also I am going to install some soffit baffles to prevent any more blockage of the soffit vents.

Any ideas would be great.

I should also note that the reason for the fiberglass rolls is so that it would be easier to get anything done if I need to go up there again. This way I can just move the fiberglass off to the side and crawl around on the joists.

Also, my joists are spaced at 17.5" OC and that is why I'm considering the cellulose as opposed to all fiberglass.

To be code-compliant the electrical junction boxes may not be covered with insulation but must always be "accessible".

I think you will find that the cellulose won't "pour" as you would like. Cellulose is densely packed in the bales that you will purchase and needs to be broken up and that is easiest with a blowing machine. Further, the cellulose is, in my opinion, a better insulating medium than is fiberglass. I suggest that you forget about the idea of adding first cellulose to the top of the joists and then adding fiberglass on top of the cellulose and just fill to the desired R rating with cellulose blown in after you have properly baffled the soffit vents so they won't be blocked.

You can rent a blower or have the entire job done by an insulation contractor. If you DIY then get a blower that has an agitator bar to break up the cellulose before it gets to the blower proper. It takes a minimum of two people to do the blowing, one to keep the blower hopper filled and one to manipulate the hose.

If your existing fiberglass has a vapor retardant (either Kraft paper or aluminized paper) and it is facing up (it should be towards the ceiling drywall) then be sure to slash it with a utility knife before adding additional insulation.

My wife and I DIY'd 8" of blown in cellulose (90 bales) on top of 7-8" of existing cellulose over 2000 sq. feet of attic. We waited until a cool weekend and had the machine & insulation delivered. Wife kept the machine filled and I was in the attic. It really helped to have walkie-talkies when the machine jammed (on occasions) and when one of us wanted a break. Wear a good breathing mask - not one of those rubber-band cheapies - it gets incredibly dusty. I also wore a head lamp because there are a lot of dark areas in our attic. I cut a straight length of clothes hanger wire and taped a 16" mark on the wire -- that way I could measure the insulation depth from time-to-time to keep it consistent.

I agree w/ Furd! Cellulose is, in my opinion, much better than fiberglass. If there is anyway to put the cellulose up there where your crawl area isn't then do it. But, make sure not to cover the soffit vents. You can get rafter vents that are made for this so you can blow in the cellulose at 12 inches deep or what not. Here is a website that I like to forward, b/c it helped me w/ calculating how many bails I will need and what not. GreenFiber.com || How to Install : Step One (http://www.cocooninsulation.com/homeowners/how_to_one.asp)


Definatly need a breathing mask like M1 said above. It is terrible to breath it in and you'll blow black snot for the next 2 days. I did my exterior walls and attic with this stuff and what a difference in heating bills and even its a great sound barrier. This stuff also settles so say you blow it in your attic at 12 inches deep it will settle to roughly 10 or so.

Good luck

I would at least explore some professional qoutes for a blowing in insulation. I paid $700 for blown in R-49 in 1300 sqft of roof. I did all the sealing and vent work. I remember the price was very competitive to DIY batts. I opted against blow in DIY since too many people complained about their wife as a helper. The best part was watching someone else crawl around the attic. Their equipment is so much nicer it only took them about an hour. Overall, well worth the costs. Don't forget to bring the access door up to R-49 also.

good luck

Thanks for all the replies. After more discussion with my wife and more research from this website, your answers and other websites we've decided that we're going to blow in cellulose.

So I guess that means I'll be filling any holes with the spray in foam this weekend and when I get my Accuvent soffit baffles I'll install those, lay down some 6 mil plastic sheathing and I guess I'll be ready to blow in the cellulose. I'm thinking of going to an R-60 value.

Again, thanks for the replies and any more opinions/advise is appreciated.

Good luck, it really is an easy project, but don't forget the dust masks. Buy some good ones.

Chris, do you have friends and money for beer and pizza?? That is what I did when I did my attic and walls. Beer, pizza, and friends are a great way to do this project. Was the 700 dollar price with the price of the insulation or w/o? I did my walls and attic for around 800 bucks and that includes the beer & pizza. :rolleyes:

Just a few more questions and I think I'll be ready to go. What should I do about where the chimney comes thru the attic floor? Can I just buy unfaced roll insulation and stuff it down in between the chimney and the interior walls? It's a cinder block chimney with a terra cotta insert. I don't think the cinder blocks even get warm.

Also, while blowing in the insulation how close to the area where I'm blowing it in should I be? A few inches or a few feet?

Thanks in advance.

Dont use fiberglass to seal the chimney chase. Fiberglass doesnt stop air at all. The air will be filtered and stop dirt but thats it--thats why you see black batts develop over holes. Seal it from air leaks instead with noncombustible materials. I used something called FSK board for mine along with some fire resistant foam. Read this link on how it should be done properly but here they used sheet metal. be sure to seal up any other holes in the attic floor like the tops of gable end walls and plumbing chases too but in those cases you can use 2 inch thick foamboard cut to fit and sealed with sprayfoam like great stuff. Also you can be a few feet away from the end of the hose when you blow. Thats something you will see when you start.

OHC Magazine: Chimney Chases: Sealing a Big Hole in an Old House (http://www.oldhousechronicle.org/archives/vol01/issue06/technical/chimney/chimney.html)

Chris, do you have friends and money for beer and pizza?? That is what I did when I did my attic and walls. Beer, pizza, and friends are a great way to do this project. Was the 700 dollar price with the price of the insulation or w/o? I did my walls and attic for around 800 bucks and that includes the beer & pizza. :rolleyes:

Of course it included the cost of insulation. When I priced it out, the materials alone were around $500. Thats not including, how do you get all that insulation and the machine home without multiple trips? I also remember the store with the best deal, only offered a machine that needed 220V. So I would have had to put some temporary power source in to power the thing. It also needed to reach two different attic spaces. I even use to install insulation (16 yrs ago), so I was aware of the job requirements. I also heard enough other people complain about the free blower provided, taking all day to put in less insulation than I needed. Top it off, qoutes are free, I didn't even have to be there to get a qoute. They just measure from the outside and would probably give you an over the phone qoute. Now maybe a good time with new construction being limited. For me it was well worth the small additional costs. Once you reach a certian age, friends don't ask eachother to do these types of thing, or to help you move (another service, well worth the costs).

I would definately do my own sealing of gaps, 20" of insulation covers up alot of shortcuts. I would also try to minimize disturbing the insulation after installation, by completing any attics projects before doing it.

Didn't mean anything bad when I said that, I was joking around. :) I was lucky enough to have a truck and a trailer and I bought 50+ bags and brought the machine home all in one trip. I also had enough hose to go up 2 story's and threw my attic window.