Fiberglass Batt vs. Blown-in Insulation?

[Iplayfarmer]

I'm to the stage in my basement re-model where I'm planning insulation. I had a guy quote me a price on blown in insulation that is within pennys of the cost of buying the material for batt insulation.

What's the collective wisdom from TBN? Is the blown in cellulose stuff as good as the fiberglass batts? Does it settle over time?

I'd like to go with the blown in stuff because the guy would do all the work. If I get batts then I'll have to put it in.

 

[PointyHairedBoss]

My personal preference is rock wool insulation (called Roxul here in Canada). It comes in batts like fiberglass but is more rigid.

The theroretical R value is a little higher than fiberglass but in practice it is much better. When you fill a stud space with fiberglass, it often bunches up where it touches the studs, wires, junction boxes etc. & you lose some of the insulating value because of those voids. Roxul is quite stiff by comparison & you cut it with a serated edge bread knife to go around obstructions. For example, if you have a wire through the stud space, cut the back of the batt about half way through & fit it over the wire. It stays quite stiff & completely fills the stud space. If you have an electrical box, cut out a square of the insulation & you will be tight all around the box.

I don't like blown insulation because it settles over time.

 

[Zick]

Both will settle but cellulose does more than fiberglass. Cellulose also cost quite a bit less than fiberglass.
I think cellulose does a good job and cost less even if you have to add a little more to make up for the settling.
We have blown in fiberglass in our new house but I'm thinking of topping it off with cellulose later on.

 

[Scooby074]

My personal preference is rock wool insulation (called Roxul here in Canada). It comes in batts like fiberglass but is more rigid.

The theroretical R value is a little higher than fiberglass but in practice it is much better. When you fill a stud space with fiberglass, it often bunches up where it touches the studs, wires, junction boxes etc. & you lose some of the insulating value because of those voids. Roxul is quite stiff by comparison & you cut it with a serated edge bread knife to go around obstructions. For example, if you have a wire through the stud space, cut the back of the batt about half way through & fit it over the wire. It stays quite stiff & completely fills the stud space. If you have an electrical box, cut out a square of the insulation & you will be tight all around the box.

I don't like blown insulation because it settles over time.

Yes but Roxul is SO MUCH money. Way more than FG. Good product though. If im at roxuls price point, im going with spray in PU foam. way tighter.

 

[jonyyuma]

My personal preference is rock wool insulation (called Roxul here in Canada). It comes in batts like fiberglass but is more rigid.

The theroretical R value is a little higher than fiberglass but in practice it is much better. When you fill a stud space with fiberglass, it often bunches up where it touches the studs, wires, junction boxes etc. & you lose some of the insulating value because of those voids. Roxul is quite stiff by comparison & you cut it with a serated edge bread knife to go around obstructions. For example, if you have a wire through the stud space, cut the back of the batt about half way through & fit it over the wire. It stays quite stiff & completely fills the stud space. If you have an electrical box, cut out a square of the insulation & you will be tight all around the box.

I don't like blown insulation because it settles over time.

Pointy, I haven't seen any rockwool down here in years. It is hard to work with, and if i remember it irritates the skin and eyes.Fiberglass,celluloid and zonolite, plus urethane spray foam here. I used celluloids, if you blow it over fiberglass batts, yes it will compact down the batts. It also filled in the spaces where the glass was not consistant in the attic. I did notice that mice will go right on thru all of it. I buy a fresh box of bait every winter to feed them.My utility bill tumbled after I blew the attic, therefore it was very worth while. I am now laying foilbacked jacket up on top of all my insulation, to reflect heat in the summer,per new local energy regulations.Jy.

 

[PointyHairedBoss]

Yes but Roxul is SO MUCH money. Way more than FG. Good product though. If im at roxuls price point, im going with spray in PU foam. way tighter.

I did our cottage (future home) with Roxul - R21 walls, R35 roof/ceiling (no attic) 6 years ago. It's not a large building - 1 1/2 story, about 1600 SqFt. total. Additional cost over fiberglass was about $1000. It does a better job than fiberglass so I thought the long term fuel savings would pay. PU foam was way more above the cost of Roxul but I used it for the basement/crawl space because it does such a great job of sealing all the nooks & crannies between the joists.

 

[PointyHairedBoss]

... It is hard to work with, and if i remember it irritates the skin and eyes. ... .

I find the opposite on both points. For me, Roxul is easier to work with. And I find fiberglass is itchier. Of course you should use a mask when installing either - bad stuff to breathe.

 

[jonyyuma]

Exactly, right, breathing anything but clean air is bad. I don't remember which seems to have been the worst to install. I do have some very old rockwool installed over my garage. It does not seem to be doing anything but making it warmer? Jy.

 

[Scooby074]

I did our cottage (future home) with Roxul - R21 walls, R35 roof/ceiling (no attic) 6 years ago. It's not a large building - 1 1/2 story, about 1600 SqFt. total. Additional cost over fiberglass was about $1000. It does a better job than fiberglass so I thought the long term fuel savings would pay. PU foam was way more above the cost of Roxul but I used it for the basement/crawl space because it does such a great job of sealing all the nooks & crannies between the joists.

I talked to the Roxul guys at a show and i think they said something like 30- 40% more then FG. For somewhat limited benefit. (they tried the whole Fireproof and mold proof "what about your family" line on me too. I wasnt impressed). Id like to support them. If the premium was 5-10% maybe

 

[Iplayfarmer]

...I think cellulose does a good job and cost less even if you have to add a little more to make up for the settling.
We have blown in fiberglass in our new house but I'm thinking of topping it off with cellulose later on.

This is going into finished ceiling in the basement... i.e. It will be encased in sheetrock. I won't have the opportunity later to add a little more.

Since you mentioned basement, I assume that access is good so I would go with DIY fiberglass batts.

Everything is torn out now. Access is great. I already have the r-13 for the walls as I got it surplus. All I need is the basement ceiling. What has me confused right now is that I can get the blow-in stuff installed cheaper than I can buy the batt to do it myself. That has me wondering what the trade-offs are to the cheaper blown in insulation.