# insulation Batts or Blown



## SPS-1 (Oct 21, 2008)

Mostly, its just dollars per R.
However, consider that fiberglass, flows air too readily, so you lose some heat through convection currents (which are not measured in R value.). Cellulose supposed to be less convection losses

Myself, I like rockwool batts.

(Boy, this thread has the possibility of more opinions than drywall long side vertical or horizontal thread)


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## SLSTech (Jan 19, 2021)

Batts are fine if installed perfectly - no gaps, compressions.... one layer as deep as the trusses, then the next layer over it running across the trusses/rafters. Guess what it is basically impossible to do right with trusses but easy enough with rafters. With that while it costs a little more, blown in can more easily fill in around the framing members leaving no gaps, etc... The problem is most places look like the hills of Kansas which is also just as worthless - should be perfectly flat with no lumps unless you are covering over something else. 
But here is the biggest thing, if you don't do the prep work first, neither will perform as intended. - here is a piece on attic insulation I did which has links to past articles which you should check out especially on air sealing & baffles: Air Sealing: Attic Floor Insulation (thehtrc.com)


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## mark sr (Jun 13, 2017)

Batts are easier to place and can be done as you have time. Blown insulation does a better job of insuring there are no gaps.


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## Bud9051 (Nov 11, 2015)

Once you use blown-in that's it, you or other workers shouldn't be going up there for anything. A raised walkway can provide some access if you put it in before you blow.

I like the Roxul (rockwool) as mentioned because it is very dense and easy to get a good installation.

Bud


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## dtbingle (Jul 19, 2017)

Ran into this same debate......

Knowing that there will be future attic/remodel work for rooms below, a full 14+ inches of blown in would be a massive pain to deal with if I have to go up there.

We decided to go with a middle ground....blown in cellulose for 6" (just under R19) to top of ceiling joist in the attic to avoid having to cut batts around a 1000 different obstacles. Then R30 batt insulation on top of the blown-in for R49 total. This way, it will be more manageable to move insulation out of the way for future work.

Basically this:





And it would be worthwhile to pick up a couple cans of spray foam and air seal while insulation is not there. Also add attic ventilation if needed (rafter vent baffles, etc).


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## SPS-1 (Oct 21, 2008)

That is similar to what I did in my last house.
I had the original blown in. Hard to tell the nominal amount (very inconsistent) but probably about R32 judging by the age of the house. Roughly to top of joists.
I put first one layer of R22 Rockwool batts perpendicular to the joists, then another layer of R22 Rockwool on top of that, perpendicular to the first layer of batts.
I had a well insulated ceiling after that exercise.


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