Roxul in ceiling? Or waste of $$?

[diggler306]

I'm nearing the insulation stage of finishing my garage, and I'm already planning to insulate my 2x4 walls 16" OC with Roxul insulation. (Location Saskatchewan, Canada)

What I'm wondering is if I should bother continuing with the Roxul in the ceiling, or if I should use pink batts or fiberglass blow in. Ceiling has 2x6 joists 24"OC hanging off a center beam. I'll be finishing the ceiling with drywall, and using the attic for light cold storage.

Roxul is just so easy to work with, but is it a waste of $$ in the ceiling? I've got a 6'x6' floored area that will only be able to get R22, but I'm hoping to get the rest up to at least R30.

Thoughts? I just don't hear of many people doing it.

 

[Fueler]

Working with Roxul at the moment. No doubt in my mind, Roxul everything.

 

[Paul1956]

The only downside is that fitting Roxul up in the ceiling will
be more work given the cutting and fitting of the pieces
than doing blown-in... which is a 2-person job.

 

[DirtRoad]

If you do your doing it backwards. Roxul in the ceiling, fiberglass in the walls.

Or if you have a bottomless wallet roxul all of it.

 

[mypov]

I dunno. I've been reading a while and I like blown I insulation for attics. I am not really a believer of it being fire resistant. But, if there is a file in your building that is severe enough to test the fire resistance of your insulation, I think the building would be beyond repair anyway. The advantage of blown I insulation is you are able to insulate more efficiently, and prevent increased likely hood of thermal bridging that you may get with batt insulation. So, if it were me, I would use blown in cellulose for the roof, and Roxul insulation for the walls.

 

[theoldwizard1]

Roxul (generically called mineral wool) biggest benefits, besides insulation, are sound deadening and fire resistance. If you don't need these features, you are probably paying too much.

Blown cellulose is typically the most cost effective insulation. Easy to do in a ceiling if there is no floor above. You can pile it as high as you want, as long as you don't block and soffit vents.

Installation of cellulose in a wall cavity is typically done "wet" and requires some type of wall board (sheet rock, OSB) to be installed within a few days. You can install it "dry" in walls but that requires skim/netting to hold it in place

 

[diggler306]

Doing some calculations. My 24x24 would run about $510 for a single R22 layer of Roxul batts. Double that to get R40 and it's over $1000.

According to Owens Corning's online calculator, AtticCat blown in comes in around $615 for R60.

Hmm...that difference is significant.

 

[tyndall]

Confined spaces, such as walls or vaulted ceilings should get roxul due to higher r-value. Open areas like an attic, I'd go with cheaper blown-in fiberglass and don't stop till you see at least r40. Of course where you are I'd also shim out the walls with 2x2's to get some r22 in there.

 

[the gypsy]

Hey mypov, I have seen a video on the net where a fire department demonstrates the difference between fibreglass and roxul. I will try to find it and post it.

 

[diggler306]

Confined spaces, such as walls or vaulted ceilings should get roxul due to higher r-value. Open areas like an attic, I'd go with cheaper blown-in fiberglass and don't stop till you see at least r40. Of course where you are I'd also shim out the walls with 2x2's to get some r22 in there.

Thanks for the input. If this was my "forever home" I'd be shimming the walls out too. It gets wicked cold here in winter.

 

[norcaljr]

I'm using Roxul in the walls and ceiling of my house and garage. 2 bedrooms are above the garage, so I'm looking at it for noise, fireproofing and R-Value. It's so easy to install. If I had a attic above the garage, I would do a layer of the Roxul, the do blow insullation on top of that.

 

[jvitez]

Roxul is what I used in my garage walls, excellent stuff. I see no need for using it in an attic space. I put fibreglass batts in my old garage's attic and it was a pain to install, very fiddly work. Blown in is better in an attic: easier, cheaper, covers everything equally well with no gaps like batts.

I prefer blown in cellulose over fibreglass. There are several threads about the differences.

 

[diggler306]

I'm using Roxul in the walls and ceiling of my house and garage. 2 bedrooms are above the garage, so I'm looking at it for noise, fireproofing and R-Value. It's so easy to install. If I had a attic above the garage, I would do a layer of the Roxul, the do blow insullation on top of that.

Never thought of doing both! Good way to get the benefits of soundproofing and fire resistance, but keeping the cost down to get the desired R value.

 

[Highbeam]

Only a fool would roll batts in an attic. More cost, inferior job to blown in. As i recall, there is a roxul loose fill product you migh consider as well.

 

[theoldwizard1]

Doing some calculations. My 24x24 would run about $510 for a single R22 layer of Roxul batts. Double that to get R40 and it's over $1000.

According to Owens Corning's online calculator, AtticCat blown in comes in around $615 for R60.

Hmm...that difference is significant.

Check the pricing on blown cellulose. I'll bet it is cheaper.