Insulating 40x30 garage in SE US

[brachus12]

Looking to insulate my detached 40x30x10 garage soon. I've read many posts here about Roxul, but the majority are from posters in colder northern climates.

Has anyone in the southeastern US used Roxul? How does it handle the heat and excessive humidity? Most likely I will be cooling my shop more often than heating it.


Brachus

 

[Highbeam]

Seems the only people that push roxul are those that have bought it. It costs more than standard FG and I can't see why.

 

[brachus12]

The fire resistance and sound-dampening characteristics are very appealing to me.

 

[MScott]

Seems the only people that push roxul are those that have bought it. It costs more than standard FG and I can't see why.

I just finished installing roxul in my basement. Having done a previous house with fibreglass, I can recommend roxul completely. It does not make you itch, or give you breathing problems, it is much better at sound absorption, it does not slump in the wall cavities, it is much easier to cut and fit, it is water repellent and mildew resistant, it does not support mould and it is not attractive to mice for use as bedding materials. Being made from stone, it is also very resistant to fire so is much safer. Cost difference for the basement was less than $100....certainly well worth the extra cost if only for the lack of itching.
I will be using it in my garage when I build it this year.

 

[Gunnert]

I did FG in the walls and spray foam ceiling and eaves. If you can afford it, I'd do the ceiling/eaves in foam. I know it's expensive but for my .02, it's worth every penny.

 

[Highbeam]

If the cost was really close then just the less itchiness might be enough reason. None of the rest make sense. FG absorbs sound, isn't flammable as if that matters, won't mold, etc. Compared to FG, the roxul doesn't seem better except for installation labor.

The cost should be sompared for the application at hand. Roxul is a non-standard product so it will need some sort of highly redeeming value. Roxul is not readily available and the options are small.

 

[theoldwizard1]

Also sold under the brand Rockwool.

 

[MScott]

If the cost was really close then just the less itchiness might be enough reason. None of the rest make sense. FG absorbs sound, isn't flammable as if that matters, won't mold, etc. Compared to FG, the roxul doesn't seem better except for installation labor.

The cost should be sompared for the application at hand. Roxul is a non-standard product so it will need some sort of highly redeeming value. Roxul is not readily available and the options are small.

Perhaps it's a location issue. Here, Roxul is as easily available as regular fibreglass and in all usual dimensions. I also take issue with your statement that FG won't mold. I removed a considerable amount of fibreglass insulation in a remodleling job where there had been some leakage. The FG was black with mildew and mould. I have never seen this with Roxul. I also believe that flammability does matter.

 

[Highbeam]

I shouldn't say it won't mold, if you spill something organic on it for a fuel source then that fuel could mold. Do you actually think that something about the roxul makes it less likely to mold? That is a nice feature if so.

My structure is made of wood. Neither FG or roxul are going to burst into flames but the wood will.

The roxul, if priced competitively, might just win out on the installation labors but the other stuff sounds suspicious.

 

[Highbeam]

Here it is at HD for over 1$ per SF, regular 2x6 wall.

The Roxul R-23 15-1/4 in. x 4 ft. Steel/Basalt Insulation is Energy Star qualified and resists fire, rot, mold, mildew and bacterial growth. Its flexible material friction fits during installation for added efficiency. 39.8 SF and $40.28 for unfaced. Note that it only resists fire, mold, etc.

FG R-19 15x 93 inch batts, faced, are $44.17 for 77SF.

So the cost of FG, even faced, is nearly half. Plenty of folks go cheap on insulation and some skip it all together. When you choose something that costs double you need to have a reason. Fiberglass also resists mold, fire, etc.

 

[works4me]

I went with Roxul on my garage/workshop in Houston and I'm very happy with it. The main reasons I felt it was worth the extra cost even in a hot climate were:

1. Easy installation/Less noxious (i.e. not itchy)
2. Significantly better fire protection for my workshop
3. Significantly better sound deadening for my neighbors & myself

And don't forget that even in a hot climate insulation value is important. Roxul is slightly better than normal insulation (R-23 vs. R-19).

My 2c

 

[Highbeam]

You can pay extra for R-21 FG in the same 2x6 wall. Not R-23 though.

How do you, or anybody, quantify the sound reduction over all of the other types of insulation? Roxul sells a "safe n sound" product for sound deadening.

 

[works4me]

You can pay extra for R-21 FG in the same 2x6 wall. Not R-23 though.

How do you, or anybody, quantify the sound reduction over all of the other types of insulation? Roxul sells a "safe n sound" product for sound deadening.

FYI the Safe n sound product is exactly the same as the exterior wall insulation product I used - just thinner (for 2x4 interior walls). Coincidentally I just saw a TV program a couple of days ago where they installed it in a 2nd story floor to block sound to the unit below.

I haven't done any scientific tests (although I could pull out my dbMeter...hmmm), but it is considerably more quiet than my old garage. Also, I'm 50' from a major thoroughfare & I can't hear any sound from it at all. Moreover, I was doing some cutting with my Dry Cut saw last weekend (VERY loud) and I asked my wife if it was bothering her (about 30' away)...she said she didn't even notice it!