Correct way to install insulation

[packpride85]

So just bought a hour with a two car garage and I'm pretty excited about "customizing" it to my liking. I already have a thread over in the flooring section but I wanted to get some opinions on insulation.

It's an attached garage with insulation/drywall already installed on the walls attached to the house and the ceiling (see attachment). The walls to the outside are not insulated. Before next winter I plan on adding a 240V garage heater and probably some of these insulation batts:

http://www.homedepot.com/p/Owens-Co...-Insulation-Roll-15-in-x-32-ft-RF10/202585857

Here are my questions:
1. Which way is the kraft supposed to face for these exterior walls? Some say the paper should be facing the inside of the garage while some say they should face the outside.
2. Is it necessary to put some kind of fire resistant sheeting or something over the kraft (if facing towards the inside)? I don't necessary want to go through the effort to drywall everything.

 

[CNGsaves]

What country are you in ?? What's your climate like ??

Now would be good time to Update GJ Profile with City/State/Country so you'll have chance to get best advice.

What heat source do you have in garage, and what temps are you attempting to maintain in the garage ??

As general rule, paper side of insulation generally goes to "warm side" to act as vapor barrier (thus inside). However, this is for "normal" climate areas which may not apply to you if in delta congo with 95% humidity !!

 

[packpride85]

What country are you in ?? What's your climate like ??

Now would be good time to Update GJ Profile with City/State/Country so you'll have chance to get best advice.

What heat source do you have in garage, and what temps are you attempting to maintain in the garage ??

As general rule, paper side of insulation generally goes to "warm side" to act as vapor barrier (thus inside). However, this is for "normal" climate areas which may not apply to you if in delta congo with 95% humidity !!

I'm in central NC area. The heat source would be a 5000w electric garage heater. The "average" low during the winter is 32 but this year we saw it drop down to 5 degrees. For the purposes of working on project it would be great to have it heat to 50 degrees inside the garage if the outdoor temp was around 30.

 

[mustangmike6996]

I covered my walls with 1/2" drywall after I put insulation in. Some things that you should look out for when installing insulation:

Buy the correct width rolls for your stud spacing. Examples. 2X4 studs with 16 inch on center spacing (that way it fits correctly)

Insulate around door openings and windows if you have access to the areas. This step is often skipped when installing windows or doors and will cause a draft or cold spot.

Dont stuff/pack the insulation in. It has to not be compressed so it can actually insulate.

 

[ms fowler]

Kraft paper BURNS. With all the possible accidents just waiting in a garage, do you really want to add fire to the risks? Cover the Kraft paper with drywall.

 

[packpride85]

Kraft paper BURNS. With all the possible accidents just waiting in a garage, do you really want to add fire to the risks? Cover the Kraft paper with drywall.

Isn't there some kind of clear plastic fire resistant sheeting that can be used as well?

 

[Gerald O]

Might as well put in R15 instead of R13. It's now available to fit in the same space as the old R13. Couple of dollars more but the amount is insignificant compared to the improvement. In our climate it doesn't matter what side you put the kraft paper on or even whether you have a vapor retarder at all. But since the wall is already constructed, there is only one way to do it; kraft paper facing the open (inside) side.

Carefully measure and cut the fiberglass bats so that they are about 1/4" to 1/2" oversized in each dimension so that they just fit snugly into the wall cavities leaving no gaps but also not having to force it in causing it to bunch up. You can use big scissors or a sharp utility knife with a straight edge.

Staple the flanges of the paper to the studs with T50 staples. You can either staple to the outer edge of the studs overlapping each bat, or you can staple to the inside face near the edge if you plan to use drywall adhesive when you install drywall. Yes, you must cover the kraft paper with a fire resistant sheeting. Drywall is the cheapest and easiest of the available options. No, there is no magical fireproof plastic sheeting to use instead.

 

[packpride85]

So something like this wouldn't work?

http://www.uline.com/Product/Detail...term=S-5133&utm_campaign=Bags,+Poly+/+Plastic

 

[Randy in Maine]

I use the 6 mil poly vs that 4 mil, but it is a good vapor barrier.

It will still burn though.

The reason gypsumboard is used is that when gypsum is "burned", it actually releases the water that is its crystal structure and tries to put out the fire.

That is why attached garages usually have a requirment to use something
like 5/8" gypsumboard so that it will buy you time to get our of the house as the garage burns.

 

[pattenp]

You basically have the same climate in NC as we do in VA. The vapor barrier(kraft paper) faces the heated space. You need to consult your local building official because of the garage being attached to living space they may require drywall because of the exposed kraft paper face.

 

[Lassen Forge]

Yeah, you need to cover your Kraft Paper (BTW Paper In) with something - be it shear wall, gypsum board, whatever. I prefer sheerwall ply because it adds structural strength from building movement and it doesn't dent or hole as easy as Gypsum when you roll your toolbox into it.

My (new) wall is 2x4 construction, but I have R-19 for 2x6 walls - it compresses, but it's fine. Remember the other side of the equation as well - it may only get down to 32 normally (our normal winter low is 12F) but what's it go UP to in the summer (ours is 88)? You may want to eventually throw an AC unit in there, or at least a good ceiling vent fan.

 

[Gerald O]

No inside vapor barrier is required in the central NC climate zone under NC building code. Because of the high humidity during many months of the cooling season, it is probably best not to use an inside vapor barrier at all to improve drying and reduce mold risks.

Kraft paper is considered a vapor retarder, not a vapor barrier. This building will come under the NC Residential code.
http://ecodes.biz/ecodes_support/fr...tial/Part_I_Residential/12NC_residential.html
NC code states insulation must have a flame spread index not greater than 25 unless covered with an approved wall finish material. Kraft faced does not meet this and so must be covered.

Heating this garage with any kind of permanently installed HVAC equipment won't likely be legal under permits without bringing it up to full current energy code requirements, and that is likely not possible as it probably does not have an insulated slab. So whether the wall finish meets code or not may be moot if the owner does not intend to get permits. However covering the kraft paper under a fire resistant wall covering is still required by the manufacturer's instructions and is the responsible thing to do.

If the OP really wants to put up faced insulation with no wall covering over it then there are fire resistant versions available:
http://www.owenscorning.com/Network...EPD---EcoTouch-Flame-Spread-25-Insulation.pdf

 

[Trey T]

Lassen: Worthy to note that R19 for 2x6 will likely not to yield R19 in 2x4 frame

 

[Firebird 1]

You can get a fire retardant, code approved foil paper to cover the insulation if you do not want the expense of drywall.