I’ve got a dillema… Till now, we’ve used fiberglass batt insulation in the homes we built, but we’re ready to change to blow in blanket insulation.
The question is – is the spray in fiberglass insulation (Johns Manville Spider System) much better than the regular FG and how does it compare to, say, NU-WOOL cellulose?
TIA,
Stan
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My opinion?
Blown-in FG is better than FG batts in terms of fully fillling a cavity, meaning it's in touch with all six sides of the bay, thus it's better at stopping convective air movement within the bay.
Blown in FG is also better than blown in cellulose in many ways. Blown FG is better at maximizing air infiltration, which means fg will give you a leakier house. With fg you'll know that it's a windy day outside. With cellulose and its superior ability to stop air infiltration, you might be suprised when you opened the door to find that it's a windy day. So with cells there's a chance you might be improperly dressed for the day. Not so with FG.
Blown FG is better at allowing more sound to pass through the insulation than cellulose, so with fg you'll know when your wife is done mowing the lawn. This way you can turn the TV off and pretend you're doing something constructive before she suprises you by coming back in the house. With the better sound attenuating properties of cellulose, you'd have been caught dead with the TV remote in one hand, a beer in the other, and potato chip dust all over your shirt. Bad husband. Bad, bad husband.
Blown fg is better at allowing radiant energy to be transmitted by the roof, through the attic insulation, and into the living envelope. With blown fg in your attic, this will allow the attic to reach temps in the 120-150 degree range in the summer. The hot temp can be good, as it will deter mice from making a home up there. Plus, the heat from the attic will be tramsitted to your second floor bedrooms, causing you to sweat through the night. It's like having a sauna for free! With cellulose, the attic environment will be kinder to anything you have stored up there, plus your HVAC equipment up there will last longer, meaning you won't be able to replace and update your air handler as often as otherwise possible.
Blown in fg is also a lot better than FG at not absorbing water. If you had a leak, the fg would get saturated and the weight of the wet insulation would likely cause the insulation to settle in the bays, resulting in no insulation and winter cold spots at the tops of your walls, as well as obvious water damage to the drywall at the bottom of the bays from the water flowing through the fg and pooling at the bottom of the bays. Cellulose holds the moisture much better than FG until it's able to gently release it in a drying cycle, so with cellulose you'd never know you had a leak.
It's all perspective, but in many ways FG is much superior to cellulose.
Again, just my opinion...
Edited 2/23/2005 4:03 pm ET by Mongo
Unbiased opinions backed by facts.... That's what I'm talking about!!!!!
Much better than using the darn search engine and reading through 500 posts :)
how'd you do dat without choking on that tongue in yur cheek ?Mike Smith Rhode Island : Design / Build / Repair / Restore
You've been around long enough to know that I bit that tongue clean off years ago.