# Batting over cellulose?



## cschwehr (Mar 8, 2011)

Anyone got any recommendations for me to upgrade a blown in cellulose ~R-30 attic to >=R-60?

I am replacing the junk, deformed soffit venting and ensuring it is high enough... Then sealing all the penetration and chases. But could I add rock wool batting? Or is cellulose the best option? I just figured I could do a couple bags at a time every few weeks and spread out the work, but I guess inch for inch, cellulose wins every time right? Can I come back later to have a roof vent installed to add ventilation later with cellulose and not be as concerned with compression and movement of the original installed product?


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## iamrfixit (Jan 30, 2011)

Any type of blown product is going to perform better than batts due to continuous coverage. No matter how careful you try to install you will end up with gaps between batts, over several hundred sq feet you have a lot of joints and potential gaps. Trying to get thick batts down tightly for complete coverage in a tight confined space is difficult, blowing is easy by comparison.

Cellulose performs well, so does blown fiberglass, but you can't just dump a bag or two at a time. The R value comes from the air space that gets mixed in when the insulation is blown in. To get good performance and for ease of installation you need to blow it in. Since you are going to have to rent the machine it makes sense to do it all at once. They do have dump and rake type of cellulose but probably not the most economical way to do it and lower performing as well. It would take more product to get the same R level.

If you need to be up in the attic working on vents or wiring get that done before you blow the insulation. An occasional trip into the attic for some task won't bother it much just rake and fluff the insulation behind you as you leave. But if you need to work up there on a regular basis for a while get that done first.


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## cschwehr (Mar 8, 2011)

iamrfixit said:


> Any type of blown product is going to perform better than batts due to continuous coverage. No matter how careful you try to install you will end up with gaps between batts, over several hundred sq feet you have a lot of joints and potential gaps. Trying to get thick batts down tightly for complete coverage in a tight confined space is difficult, blowing is easy by comparison.
> 
> Cellulose performs well, so does blown fiberglass, but you can't just dump a bag or two at a time. The R value comes from the air space that gets mixed in when the insulation is blown in. To get good performance and for ease of installation you need to blow it in. Since you are going to have to rent the machine it makes sense to do it all at once. They do have dump and rake type of cellulose but probably not the most economical way to do it and lower performing as well. It would take more product to get the same R level.
> 
> If you need to be up in the attic working on vents or wiring get that done before you blow the insulation. An occasional trip into the attic for some task won't bother it much just rake and fluff the insulation behind you as you leave. But if you need to work up there on a regular basis for a while get that done first.


Figured so... I will have to wait till spring before I start cutting holes for sure. I want to add a vent before summer hits. That and I'll finish my lighting changes for the rooms, you have to enjoy a master bedroom with a single octagon box four feet off the wall in between the closets in a 14x20 room that the previous owner installed a 12v MR-16 track light on. lol


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