What are the main pros/cons between the two. I am going to be having my attic re-insulated over the winter and these are the main options in this area. From what I have heard so far:
Fiberglass Pros: Cost, lifespan, not as dusty Cons: Not as efficent, Its fiberglass
Cellulose: Pros: More efficent, Green Cons: less lifespan than fiberglass, dust
Are there any others? What have your experiences been? The house was built in 1975 and still has the original blown in fiberglass, with fiberglass batts in the added on game room.
I am going to be adding on to the existing fiber glass (or whats left of it) on one side of the house (Kitchen, Dining room and living room) and probably completely remove the old fiberglass on the other half (bedrooms and added on game-room).
Cellulose also makes your house quieter. It absorbs sound much better than fiberglass does. I don't know how well it holds up to the uber-humidity of the Houston area though.
I'm in coastal SC and cellulose seems to hold up well to humidity which surprises me. I had a townhouse with something like 18 inches of cellulose in the attic and it seemed to have no damage at all, best part was the home had a metal roof and I could not hear the roof when it stormed out. Dead quite inside but outside you could hear the rain hitting the metal roof for sure. This home was well insulated and it was very quite. I know the attic was cell, crawl space was fiberglass but not sure what they used in the walls???
I'm thinking about adding a layer of cellulose in my attic to bump up the R value but I'm mostly looking for less sound transmission.
When I was researching it, it seemed like cellulose had to be packed in pretty tightly in order to be effective. Among other things, you risk it settling and leaving a top portion of your wall uninsulated.
For this reason, I would think it would be near-impossible to fish cables through a wall with cellulose insulation, rather than merely difficult with fiberglass.
I ended up getting fiberglass batts in most of the house, and blown in fiberglass in the attic. As well they installed a vapour barrier. I have one room with fiberglass insulation, and no vapour barrier, which wasn't part of that renovation. The difference is tremendous.
Fiberglass is a poor insulator, too easy to install wrong and let air blow past it. Cellulose is far better for filling the gaps but closed cell foam is the ultimate.
There is closed-cell spray foam insulation... it will seal your house. Generally, however, you would have to remove existing insulation to get good results and lower heating / cooling bills.
If you have blown fiberglass in the attic, can you blow cellulose on top of it? I am pretty sure I have fiber glass in my attic and I know it was blown in. My house was built in 1980 but they may have added more insulation at some point.
I frequently have to wade thru knee high polyester looking stuff/fuzz in people attics. Seems down here in southern Az an awful lot of the higher end homes have that stuff.
It looks a lot like what you find all over your backyard after a couple of puppies have had at it with a (formerly) good sleeping bag. (yes, first hand experience with the bag situation)
Thats all I know about that stuff besides it sticks ALL OVER my clothes and I spread it everywhere & doesn't give any itches...
I would think it would be near-impossible to fish cables through a wall with cellulose insulation, rather than merely difficult with fiberglass
Nope. fishing a wall is never fun, but cellulose pushes out of the way fairly easily, whereas fiberglass batts tend to bunch up in front of whatever you're fishing with, and if you are drilling, fiberglass will wad up on the bit like cotton candy.
The Cadillac solution would be to remove the existing, lay down a couple of inches of closed-cell spray foam, then 18" of cellulose on top. You get the air/vapour barrier from the foam; then the insulation of the cellulose.
If you have fibreglass now; putting cellulose on top maybe a problem - it's heavier; and will compress the fibreglass, pretty much ruining the insulation value.
Around here, it's pretty much all blown cellulose for attic insulation... It's cheap, it's effective.
That said - you're in a 'cooling' climate - I'm in a 'heating' one... So don't know how transferable what 'we' do is for your application.
Cadillac solution for the OPs area would be to remove the existing insulation and insulate the underside of the roof deck with closed cell foam creating a non-vented, conditioned attic space. Summer cooling is the main issue in Texas and with all of the ducts and many times the air handler itself in the attic this method is the most energy efficient. If there is enough space in the attic to do the work it would be a good option to look into.
