The usefulness of vapour barriers in any mixed climate is in doubt. (Your profile simply says United States.) In my last build, in a cold climate, I filled the space between the studs with high density fg, then sheathed it in 1" XPS and drywall. The vapour barrier was already in place on the interior side of the studs.

Do you want ANY heat in the garage?

If you insulate the wall the garage is libel to approach outside temps (especially if IT has no insulation.

If the garage wall is out you have the perfect opportunity to both sound seal and protect from exhaust gases from the cars, etc.

I'd wrap every electrical/utility penetration, use Quiet Roc insulation, shingle it with building paper*, use acoustical sealant wherever it was useful and use the sound deadening drywall with two coats at least of mud on taped joints. Seal the drywall top and bottom as well.

* start with a half roll, then put a full roll completely over that, next strip goes half way over that and so on...so you end up with a double layer of building paper all the way up the wall, overlapping like shingles. Building paper is cheap and until you do this and live with it you won't believe the benefits. sound, air movement is cut way down. We deal with (and live in) older homes and if the siding comes off for whatever reason this method is a given, regardless of other methods also used.

We used R21 fiberglass.

You can seal the garage for carbon monoxide and sound or you can just turn the engine off when you park your car in the garage.

Everything depends on where you live and we don't know that.

Quiet Rock? Only if the OP's kids have a garage band. And it will do nothing for the flanking sound pathways. (Or angry neighbours!)

Here it is code to seal an attached garage off for vehicle exhaust, for good reason. Lawn mowers, cars, etc all off gas for a time after shut down and non critical thinking folks often warm up or run power equipment in a garage. I personally know folks who use their grill in the garage to avoid being rained on in winter.

as for sound, well you never will know how quiet it can get until you do it.

Picture your garage door open and a large truck rumbles past. sound enters the garage where it amplifies not unlike the inside of a drum. Seeking the path of least resistance, it travels into the home via the unsealed wall. Why not dampen that? Its not just in garage sound my suggestion will ameliorate, its the daily tire slap of passing traffic, the background noise that surrounds us.

The OP has a perfect opportunity do do so and for minimal cost...why not?

Brickeyee - you make a good point. Right now the garage stays pretty warm in the winter - which is great for working on vehicles in January! Plus, I have plants that I overwinter in the garage. I do have a oil heater in the garage that I use on a regular basis but maybe that will not be enough if we insulate it really well.

The other sides of the garage are not insulated - neither is the garage door. Maybe we should focus on that also to make the garage more comfortable for vehicle work?

The need to increase sound isolation from the garage seems of little value to me but if you want to do it, building paper and QuietRoc will be less effective than adding a second layer of drywall. To go beyond that level usually requires a resilient channel system under the drywall.

If you need to seal the wall the vapor retarder will do that and you would only need to put a gasket around the door. An automatic door closer would be worthwhile if you are prone to running engines and lighting fires in your garage with the garage door closed. I would also recommend a psychiatric evaluation.

No need to be snarky, macv.

Using the escaped heat from the home to heat the garage flies directly in the face of current best practices on energy efficiency.

If you want a warm garage, insulate and heat it. Don't rely on having heat loss from your home warm your garage.

metaxa, if you give uninformed oddball advice to unsuspecting homeowners you should expect other members to respond with their opinions. I'm probably not not the first person to tell you this.

Putting fire and sound rated insulation between a garage and home is oddball?

Sealing an attached garage from the house is oddball?

Our home warranty provider insists on shingled building paper before they will provide the warranty...but you must be more informed than they are.

I'm probably not not the first person to tell you this.
Probably not but you are the first in a great long time to do so in such a self-important and pompous manner.

I don't know what you mean by "Quiet Roc insulation" but Quiet Rock is a brand of gypsum board that provides sound reduction in locations where a thicker wall is not possible or not desirable and you must pay a premium price for that feature.

Some kinds of insulation are combustible and some aren't but there is no such thing as "fire rated" insulation. In general, fire ratings are given to complete wall and floor/ceiling assemblies after testing by fire exposure from both sides and then a hose stream test. The fire rating of such assemblies is unchanged by the presence of insulation.

I don't know of any kind of insulation that offers a substantial reduction in sound transfer in a thickness less than 8 inches but I wish I did. What a thin layer of insulation does in a stud wall is reduce the transfer of sound through unaligned cracks in both sides of the wall so it is modestly beneficial especially if there are a lot of unsealed cracks and penetrations. However, the difference in sound reduction between thermal insulation batts and so-called "acoustic" insulation batts cannot be measured in the field so the difference exists primarily in marketing information.

Home warranties are a total rip off. What would an insurance scam artist need to know about building a house?

In a cold climate a shared wall between a house and an unheated garage should be sealed on the warm side with a vapor retarder membrane. A vapor permeable air barrier could be installed on the garage side to reduce air infiltration but a material rated for low air permeance should be used and that could be a lot of materials but it would certainly not be overlapping sheets of building paper/felt.

For a membrane to be an effective air-barrier it must have an air permeance rating of less than .02
-Tyvek HomeWrap is .01
-a layer of gypsum board is .0196
-asphalt felt (building paper) is .3962 (20 times more permeable than drywall)

And those numbers are for a 1 meter square sample sheet so unsealed or lapped joints in the field would increase the air permeance to the point that it would have no practical purpose.

I say again: if for whatever reason a homeowner wants to increase the fire resistance, air barrier and acoustic performance of a shared garage wall, all that is needed is a properly installed and double layer of gyp board on the garage side and some kind of insulation in the cavity.

Whether or not to install a vapor retarder can only be determined with knowledge of all the relevant climate and heating information.

My comments are sometimes appreciated and sometimes not but rightly or wrongly I feel a responsibility to the inexperienced and/or non-building-professional members of the forum to contest what I think are incorrect and/or misleading statements when I read them. If that seems self-important and pompous to you, so be it. I just want people to be able to build their houses well and I assume that is why they are here.

It just occurred to me that the home warranty company requirement for building paper is as a "weather barrier" rather than as an "air barrier". In fact, in most jurisdictions 15 lb building paper is the minimum building code required weather barrier. However, there would be no purpose for installing a weather barrier inside a garage and I'm sure the home warranty company is aware of that.

"Using the escaped heat from the home to heat the garage flies directly in the face of current best practices on energy efficiency."

What?

It is going to take energy to heat the garage if anything above outside ambient is desired.

The house central heat is liable to be more efficient than anything else.

This ranks right up there with sealing and insulating ducts in conditioned space.

There is not really any 'loss'.

I have seen plenty of folks seal and insulate basement duct-work, only to end up cutting a hole in the duct and installing a register.

The floors were suddenly as lot colder in the first floor.

It just occurred to me that the home warranty company requirement for building paper is as a "weather barrier" rather than as an "air barrier".

What if the garage door is left open and a tsunami sweeps through? You never know.

(Besides, whatever a builder does is clearly superiour to whatever some building scientists babble on about.)

all three of the sound deadening mat, drywall and insulation installations I refer to are used in the linked video. You quite rightly and everso graciously point out my having conflated the trade name of the drywall with the trade name of the insulation.

The methods used in the video are the ones we use between duplex homes, basement suites and upper floors and between garages and house walls...if we have occasion to be in there. Although they don't mention the insulation specifically, that is the stuff we use.

macv, we run a property management firm that extends over two provinces, incorporates single, multiple and mutli family units as well as commercial strata units. My partner is an award winning builder and I am not. however I do hands on management of our company and am familiar with most of the trades, our codes and best practices. Every now and then one of our units becomes a tear down and a spec home is built, highest and best use and all that. We do maybe two a year. In the early days we were in the trenches, doing the digging, the renos, the repairs ourselves. We operate in a climate that ranges from double digits below zero to triple digits above and we do it well. Our units are of top quality and we maintain and refurbish them to the highest of standards. You may chose to do just what is OK, we chose to do what is best.

My solution to the OPs query adds about $100 to his cost, max. I'll pay that to avoid noise, drafts, heat loss and such.

home warranties may be a total rip off in your country but I assure you they are not in mine.

the insulation is in fact fire rated, shame you don't seem to have knowledge or access to it...having so would make you a better builder I expect.

Building paper has been used for hundreds of years...you go with your vapour perm barriers like Tyvek and wait for the rot and mould to set it...I don't care. I've yet to see it installed correctly or read about it being installed correctly and it is a time bomb waiting to happen. google leaky condo syndrome and see where your type of building practices and house wraps get you.

Anyway, I'm done with the likes of you.
Typical American Exceptionalism. Design and build your 20 year teardowns, I'll house myself and my people in homes that need a facelift after 50 years.

Here is a link that might be useful: Sound

Fine, you win.

the Op should shove "some' insulation in and cover everything up with "some" drywall.

That is what is between each of those housing units at Harvard, right? some insulation and two sheets of drywall?

I never said building paper is an air barrier, you are so right why make stuff up?

We don't have any issues with roxul, just follow the standard fiberglass protocols, long sleeves, dust mask, gloves.

I have never met anyone so right and been so terribly wrong. I am so sorry.
I apologize over and over again.
You are so right.

enjoy.

Here is a link that might be useful: Roxul, read for yourself.

American Exceptionalism.

Interesting adaptation of a political, usually polemical, term to building science! I wonder if the lexicographers have logged other examples.

We do get an occasional laugh at other building sites over Mikey's antics, his often shaky grasp of building science, shameless self-aggrandizement and comically exaggerated masculinity. Village People anyone? (Probably just jealous of the big bucks and his rubbing shoulders with celebrities.)

"Building paper is cheap and until you do this and live with it you won't believe the benefits. sound, air movement is cut way down."

That sounded to me like a claim for double coverage building paper as an acoustic and air barrier. But if I misunderstood please tell me what is the intended function of building paper you so strongly recommend on a shared wall inside an attached garage?

Roxul, like other insulation manufacturers, likes to compare their product to low-density fiberglass rather than the higher-density kind.

When you become solely responsible for the design and material specification of buildings you quickly learn to avoid basing your decisions on published claims from manufacturers. If the information isn't backed up by independent tests or very reliable professional opinions, it should be ignored.

I don't consider Mike Holmes a reliable source; he's a less hairy version of Bob Vila on steroids.

If you want a cheap education run over to the Journal of Light Construction forum. If you want to participate you'll need to say you're a building professional; they don't like homeowners over there but anyone can watch.

Here is a link that might be useful: JLC forum

Give it up, you're right. Ever so right.
you've humiliated me online
I may need therapy.

Be the bigger man, stop hitting when a guy is down.

Any one who takes air movement and ramps that up to air barrier is way above me in intellect, knowledge and comprehension. Probably way more handsome too.

Go bug someone else, there is a guy who is advocating using uncontrolled air leakage from the main home to heat the garage. Surly he deserves a gracious and kind comment or two.

Go for a walk to the mall, tell the others there how great you are and how you took a guy who mixed up the trade name for a drywall with an insulation and destroyed him. If your Metamucil laden body will allow you to venture that far

to the OP:
slap in "some" insulation and "some" drywall and its done.
Or put in components that while they may be a bit of overkill will cause you to smile as you enjoy a quiet home, an odour free home, a safe home. And that are examples of the very same things the experts are asking for, just better.

Leave the building paper off, apparently it drives macv nuts. All it is, is one more layer, it helps. costs maybe $20 a roll.

I'm not going to respond to any more questions about energy conservation if the OP won't tell us where the house is located; it just results in pointless discussions.

Since you seem interested in my body, I should mention that it got be as far as the finals in the US Rowing Masters National Championships this year.

Here is a link that might be useful: Masters 8's

Let's see, I worked out once with this undefeated MMA fighter.

Olga the "Greek Sensation"

I'm thinking you made a pass and she decked you.

Actually, she's more into grappling! (Trained with Bas Rutten.) She won all her bouts by submission. I'll say no more.

I can see where submission might be a wise choice in any activity involving Olga. I was a grappler in college but lost interest after the surgery and took up rowing, an equally strenuous activity with a lower chance of permanent disability.