insulating attach garage

[JC522]

I've read what the r value means but what would be a good r value to use for garage insulating? I'm planning on going to home depot to buy the insulation, the 2 brands they carry are pink fibreglass (the one with pink panther on the front) and roxul, is one brand better then the other? Also where do I purchase the vapour barrier plastic because from what I've read this is needed to keep the garage up to code?

[FiveFreshFish]

Ask the Home Depot staff about the correct R-value and thickness of the vapour barrier which they also sell.

You'll also need a staple gun and Tuck Tape.

[TKRIS]

Unless you're going to spend stupid amounts of money, R value is determined by thickness. What thickness you can put in depends on your walls. If you try ramming R20 (meant for a 2x6 wall) into a 2x4 wall, you're not only wasting your money by going with the R20, but you won't even get the same insulating value as the R12. Insulation needs to have enough room to fluff up. If it's compressed, it won't insulate.

In other words, if your walls are 2x4 construction, use R12. If they're 2x6, it's up to you whether or not you think it's worthwhile to spend the extra money on R20. For the ceiling, I just used R12 on my attached garage since it shares roof space with my house, but in my previous detached I double layered R12 (2 layers of R12 was cheaper than a single layer of R20).

I've heard the mineral wool stuff is good, presuming you use the correct type of knife to cut it, but that it's a bit more of a pain in the ass to work with. YMMV, as I haven't actually done anything with it myself. I've never felt any of the alleged benefits of the Roxul justify it's increased cost.

As for vapor barrier, I always buy thick stuff. It's a bit harder to work with sometimes (sometimes easier as well), but it doesn't tear as easily, and keeping everything air tight and tear/hole free is the name of the game. Try to get someone to help you with the vapor barrier. I've always done it myself, and it fucking sucks. Especially when you've got 12' ceiling in the garage and you're scared of heights...

[Kloubek]

I am currently building a new house, and had considered insulating my garage, since I saw so many others doing it. But it made no sense, since I do not plan on heating it and I figured it would make little difference. After reading up on it, I discovered that I was right.

So in the end, I hope you plan on constantly heating this garage, or the benefits of the insulation are next to none.

Now, if you ARE heating it, then you should also know that the garage door is where much of your heat will be lost. You must install a door kit as well to get the full benefit of insulating the garage.

Just in case you didn't know on both accounts...

[Euro838]

Do as TKRIS mentioned up there but I do believe it makes a difference during winter AND summer. Your garage is not as cold in the winter since it is attached to the house and will gain heat. In the summer, it'll be cooler than if you hadn't insulated it. It might be overkill but I used R-40 for my garage roof since that's supposed to be attic stuff. I'm sure using R20 would be fine.

I'd also recommend drywalling it too just to give it a cleaner look. Might be a bit of effort but doesn't cost much more. This is all fairly easy as a DIY since it doesn't have to be perfect.

[Kloubek]

I don't see where the heat would be coming from in the winter, since the insulation of your house walls should keep the heat from escaping your living space. If you have lots of heat transfer to your garage, then you might have an insulation problem in the wall between the garage and the living space.

In the summer, I can see how it would keep the cooler air in the garage during peak hot times of the day, but that is about it.

In both cases though, you open the door to the garage and *poof* there goes 90% of the variance in temperature anyway.

Considering the price of insulating (and then drywalling makes sense), I just don't see the benfit besides the fact it *looks* a lot better.

[benyl]

All houses give off heat. Even perfectly sealed ones where the doors are never opened. Insulation only slows the rate of heat transfer.

Like it or not, your attached garage gets some heat from your house.

The heat in your house or your garage is not only held in the air. So simply opening the door doesn't drive out 90% of the heat. The heat is held in the structure as well. That is why a house with carpet usually feels warmer than one with hardwood or tile. Carpet, like insulation, holds heat better.

That being said, the heat in your garage is likely held by the concrete floor. So opening the door will let the hot air out, but once the door is closed, the new cold air will be heated by the structure.

[TKRIS]

As mentioned, I insulated my garage. It is warmer. not much, but a little. I am going to heat it, just haven't found a heater for sale yet.
There are other benefits as well. Even disregarding the slight heat gain, it "feels" warmer, because it's less drafty. More importantly, it absorbs sound and keeps it from reverberating into the house. Much quieter since I insulated.
It doesn't really cost much if you're just going to throw some R12 in the walls and ceiling, but I'd agree that the benefits aren't staggering if you're not planning on heating it.

[Euro838]

Well, for your standard garage (20x22), materials shouldn't cost more than few hundred dollars. This can also be reduced if you have a bonus room over your garage since the builder would have finished up to the bonus room.

I think it's a worthwhile investment regardless if you plan to use a heater in your garage.

I would recommend the pink stuff(Owens Corning) vs stuff you get at like Home Improvement warehouse. It may be a bit more expensive but it doesn't stink and is easier to work with. In terms of insulation, they are both the same. For drywall, probably go to Home Improvment warehouse since it's only $10 a sheet vs $12 at home depot/rona.

[Xtrema]

Originally posted by Kloubek
I don't see where the heat would be coming from in the winter, since the insulation of your house walls should keep the heat from escaping your living space. If you have lots of heat transfer to your garage, then you might have an insulation problem in the wall between the garage and the living space.

In the summer, I can see how it would keep the cooler air in the garage during peak hot times of the day, but that is about it.

In both cases though, you open the door to the garage and *poof* there goes 90% of the variance in temperature anyway.

Considering the price of insulating (and then drywalling makes sense), I just don't see the benfit besides the fact it *looks* a lot better.

I disagree.

Insulated garage will be warmer on cold days even without a heater (but I can only speak for attached garage).

You heating sources are:

A) wall shared with house.
B) hot engine(s)

We had an inside/outside thermometer in the garage. Pre insulation, the temp would be the same inside and out in the morning. Post insulation, the garage is consistently 3-4 degree higher.

[hampstor]

I've got 2 bedrooms that partially overhang into the garage - I used R12 on the walls and on the attic area that didn't have rooms above it, I doubled up on R12 there. My garage is heated - I didn't change or do anything extra to my garage door.

Regarding the different brands, next time you're in home depot check the labels on them - some of the roxul branded insulation is fire resistant (I believe it's green), some of it is sound deadening, etc. You can buy the poly there at home depot as well - i dont recall what the minimum thickness is off hand. I think it's something like 0.8mm ?

Edit: Should mention that I didn't bother with the roxul fire resistant/sound deadening stuff. I just went with the normal insulation from Rona. The insulation cost me a total of about $350 poly was about 60 and about another $240 on drywall.

[Kloubek]

I find the feedback very interesting! The last three weeks have offered little in the way of actual tasks at my work, so I was able to spend a couple of hours researching this.

I got information from at least a dozen sites, indicating the difference between insulated and non-insulated is negligible unless you have a heater.

Now it seems that people on here disagree. Xtrema even measured it!

Very interesting indeed. I may just reconsider the insulating of my garage once our house is built. If nothing else, it should help provide another barrier of protection, since our bonus room is above the garage....

[TKRIS]

Don't waste money on the sound deadening stuff.
On paper, the sound deadening stuff is marginally better in very narrow, specific frequency bands. But perceptively (according to most unbiased home theater type authorities I've found), the cheap pink batts are as good as any of the other type of batt insulation, regardless of how fancy the packaging or convincing the marketing.

Xtrema: Hot engines? That presumes one can fit running vehicles in their garage. If you have enough space in your garage for drivable vehicles, you don't have enough non-drivable vehicles.

EDIT: If you're building a house with a bonus room, not only should you insulate it very, very well for heating purposes, but I'd install resilient channel between any common floors/walls. Resilient channel isn't terribly expensive, and it'll make a huge difference in keeping the noise down.
Not an issue if all you do is park in your garage, but as noted above, I don't consider garages to be suitable places for parking...

[benyl]

I can tell you from personal experience that the room above the garage will be much colder than the rest of the house until you insulate the garage.

[hampstor]

Also - before you put up insulation, put in your outlets, lights, wire in speakers etc.

[Mibz]

Originally posted by TKRIS
Don't waste money on the sound deadening stuff.
On paper, the sound deadening stuff is marginally better in very narrow, specific frequency bands. But perceptively (according to most unbiased home theater type authorities I've found), the cheap pink batts are as good as any of the other type of batt insulation, regardless of how fancy the packaging or convincing the marketing.

Source? I need to insulate the ceiling of my drum room so I want as much absorption as possible. I was looking at the sound deadening Roxul stuff but if it's extra money for negligible difference then I won't bother.

[TKRIS]

Originally posted by Mibz
Source? I need to insulate the ceiling of my drum room so I want as much absorption as possible. I was looking at the sound deadening Roxul stuff but if it's extra money for negligible difference then I won't bother.

Yeah, I'm finishing my basement, which is why I've been looking into it. That information was gleened from spending several house digging through posts on the subject on Home Theater Forum, AVS Forum, etc., and STC and NRC ratings.

If you go here:
http://www.nrc-cnrc.gc.ca/eng/ibp/ir...ons/index.html

and enter "ir761" in the search field, you'll be able to open a document on gypsum board sound loss and transmission with about every type of insulation situation imaginable.

Here's some absorption coefficients:
http://www.bobgolds.com/AbsorptionCoefficients.htm

Here's another good link:
http://www.cmhc-schl.gc.ca/publicati...h/2000-109.htm

According to that, the difference between regular pink fiberglass insulation and mineral wool is ~1 STC point or less. For that small of a difference, I'd argue that the extra money could be put to far better use elsewhere (bass traps, high mass vinyl around ducts, etc.)

Best bang for your buck. Resilient channel to break transmission to the joists and provide an air gap, then insulation, then another air gap before hitting the ceiling/floor. Energy will be lost every time the sound waves have to penetrate through another medium, so the more things you make it pass through (using an air gap between) the more absorption you'll get. Mass of course, also plays a big role.

EDIT: It should also be noted that sound insulating varies with what frequencies are going to be most problematic. A drum kit may require specific attention to frequencies someone building a home theater room may not need to concern themselves with very much.

[sml]

I have an attached garage which is not heated and I insulated it with R20 on 2x6 studs. I can tell you that my thermometer reads 10C higher in the garage than outside in the winter. In the summer, it is consistently about 20C even if it goes up to 30C outside. That's just my experience. I say do it for the $300-$500 that it's gonna cost you, it's small potatoes comparing to the price of your house.

[JC522]

ya I have a bonus room above the garage and it gets colder but they already insulated that part of my garage and put up drywall. My gf also says she can smell the cigarette smoke when I'm in the garage smoking and she's in the bonus room, will the insulation stop that too?

[TKRIS]

More than likely isn't either insulated or heated properly. I've heard that most bonus rooms aren't.
I'd venture to say that if you can smell smoke inside, the vapor barrier isn't done properly. If the vapor barrier was correct, virtually no air from the garage would be able to get into the bonus room, so it wouldn't smell. Of course, it's probably going to smell a bit (smoke goes outside then permeates just like someone was smoking in the driveway), but it shouldn't be very noticeable.

Presuming it's not all finished and taped and a whole shitton of work, I'd be tempted to take down the drywall that's up there to make sure no insulation is compressed, and to make sure the vapor barrier was acting as an actual barrier...