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Attic insulation - batts vs blown which is best?
- Thread starter wazzabie
- Start date
billconner
Well-known member
Being discussed now in another thread.
Ceiling with vented attic space or cathedral ceiling?
Ceiling with vented attic space or cathedral ceiling?
Paraboloid
New member
- Joined
- May 8, 2023
- Messages
- 1
I did green fiber cellulose from big box in my house. DIY install was pretty simple with the rented blower and two people. It was cheap and works well as insulation and was cheap. Unfortunately It has a distinctive smell that has not gone away a year later. I have an attic vent fan and can smell the insulation from outside whenever it runs. If I had known this I might have done something different.
I made a small platform in my garage attic for storage and did batts under that and "walled" it in before doing blown in for the remainder of the attic.
I of course air sealed everything with spray foam beforehand and added soffit baffles where appropriate.
Blown in was incredibly easy albeit messy. I live in a northern climate and insulated with the blown in to around R55.
Even in the middle of winter, when it could be single digits or below, my newly installed 50k Big Maxx would hardly turn on (keeping temp around 50F) unless I had the big door opened for a period of time.
I of course air sealed everything with spray foam beforehand and added soffit baffles where appropriate.
Blown in was incredibly easy albeit messy. I live in a northern climate and insulated with the blown in to around R55.
Even in the middle of winter, when it could be single digits or below, my newly installed 50k Big Maxx would hardly turn on (keeping temp around 50F) unless I had the big door opened for a period of time.
dfiler2
Well-known member
The biggest advantage with blow in is you get it over the bottom cord of the rafters it fill in all the little areas that are hard to get to with fiberglass plus it is easy to do and easy to add more if you need it.
duneslider
Well-known member
I don't know what the cost difference is between the two but if batts are cheaper you can always come in later and blow in over the top of batts if you wanted. Its so easy to blow in that it just doesn't make sense in my mind to do batts in the ceiling.
pcmeiners
Well-known member
"Its so easy to blow in that it just doesn't make sense in my mind to do batts in the ceiling."
As to Cellulose insulation over batts....
There is a benefit to using batts first, then topping with blow insulation. If you need to cut a hole in a ceiling or you have a temporary water issue it is much more practical to have batts as a bottom layer... from someone who has had both situations. The combination of batts and blown insulation is a great combo, batts alone lose considerable r-valve to air circulation, cellulose forms an air seal for the batts.
As to Cellulose insulation over batts....
There is a benefit to using batts first, then topping with blow insulation. If you need to cut a hole in a ceiling or you have a temporary water issue it is much more practical to have batts as a bottom layer... from someone who has had both situations. The combination of batts and blown insulation is a great combo, batts alone lose considerable r-valve to air circulation, cellulose forms an air seal for the batts.
cost difference is that blown insulation is usually a lot cheaper. all the other benefits are as pointed out above. one disadvantage is that it does tend to settle, so you may need to add more at a later date, and it takes longer to install rather than simply throwing batts down in the rafter.
as @pcmeiners pointed out, the combination of batts, blown insul, and spray foam for sealing gaps and corners is ideal
as @pcmeiners pointed out, the combination of batts, blown insul, and spray foam for sealing gaps and corners is ideal
billconner
Well-known member
If any of partitions - top plate under joists - seal that. If you look at attic insulation that's been over an unsealed interior of partition, you see how much convection costs you energy.