Insulation Considerations - Batts or Blown in??


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Old 06-14-21, 10:51 AM
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Insulation Considerations - Batts or Blown in??

I have a 1969 built home in Southern California that has existing blown in insulation (fiberglass?) from what seems like back when the home was built.

As you can see in the pictures, it's well below the joist levels and is dirty (will be vacuumed completely). I currently do not use it for storage because of it's semi low pitch (4.5ft standing height inside at the ridge).

So going forward, I am stuck deciding between R38 batts or blown in cellulose or maybe a combo of batts+cellulose blown over the top?? The plans is to air seal everything possible including where the roof meets the eaves (no soffits vents) which is really tight and difficult to reach. I have plently of canned lights (mix of old and new) everywhere and some are NON-IC rated, but I think with the LED conversions it's ok now to have the insulation contact these cans. Though, that one white can in the photo most likely will be replaced because its really leaky (I can see inside). Another option is to invest in those organic "hats" to cover all the cans.

The attic is well vented with fans. Another consideration, would be to add radiant barrier against the roof rafters. I have a couple of knee walls facing the exterior (with gable vents) - would adding batts here be a good idea?

One guy I spoke to wants to use unfaced batts, but for the small difference in cost, wouldn't it be better to have them faced? I think over the years it will look/stay cleaner, but I don't think the vapor barrier is needed in an attic like mine? He also mentioned that they can pull a sheet of clear plastic over the fiberglass to keep it cleaner in the attic. Won't that trap moisture?

Anyways, how would you do it?

Thanks!





Thanks!
 
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Old 06-14-21, 03:55 PM
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Vapor retarder goes against warm side not facing up, you never put plastic over insulation and to be honest your paint on the interior serves as vaper retarder so you really dont need anything!

Cellulose itself acts as an air sealer, it's heavy and dense, and fill voids that are present with fiberglass!

Ive used cellulose in the past 3 homes, personally I would not use fiberglass, I just hate the stuff!
 
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Old 06-15-21, 05:42 PM
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This video is pretty informative: https://www.youtube.com/watch?v=osWeSqCXpcE
 
 

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