To Insulate, Or Not?

[adpostel]

Hello All, I live in Houston, TX and work on project cars as a weekend warrior type. I have a detached 2 car garage and it is unfinished. My next project for my garage is to run a sub panel off my main breaker box and run electrical and air from my compressor to needed places around the garage. I then want to finish the interior of the garage with sheetrock, and am wondering if I need to insulate the walls before I do this. My first thought was OF COURSE, but as I read more and more, I am leaning towards not insulating, as it would almost be of no use for me. Our Houston weather is hot and humid about 11 months out of the year. Furthermore, when I am in the garage working, 9 times out of 10, I have at least one of the garage doors open, if not both. I usually bring the truck/car out of the garage into the driveway to work on it, for several reasons, lighting and natural breeze, and to not make a mess in the actual garage. So for this type of use, would it even be necessary to insulate the walls? Would it do me more harm than good, because I don't even think I will insulate the very small attic portion of the garage? Any thoughts or input would be appreciated.

 

[hidollartoys]

If your garage is not shaded from the sun then you might want to install a ceiling and attic insulation with the proper attic venting. If you also install windows you can make use of the prevailing breezes for cooling. If you ever think you want to cool the interior then full insulation would be recommended. If you do insulate the entire building it will be somewhat cooler. Wall insulation will minimize the effects of radiant heating by the sun.

 

[bobs409]

I went through a season or two with no insulation in my garage while I was building it. It was HOT in there in the summers. After putting the insulation and drywall, it was so much cooler, like a whole different building.

Since your in a hot area, you might consider insulating to keep it cool. Even just the roof/ceiling would probably be a big help.

Just my opinion...


Bob

 

[brownbagg]

you want to insulate just for sound noise. I myself would not use drywall in a garage, although its a fire barrier it also get damage real easy. I would use plywood for durabilty, yes plywood will burn but you would have to hold a torch to it to get started. Grinding and welding wont do it if you have good housekeeping.

 

[bigdav160]

DO NOT INSULATE, unless you are going to air-condition the space. You are going to trap moisture and it will stay hot.

Make sure to use a radiant barrier and plenty of ventilation.

 

[Jaguar Fan]

If it were me, I would fully insulate it & also install an HVAC unit -- both to lower the humidity and cool it for more comfortable working conditions. I would put in plenty of lighting so I could work inside the garage with the doors closed. If you do this, you should also get an insulated garage door or put in aftermarket insulation in the garage door.

As you get older, you might come to appreciate a cooler place for your weekend work.

I'm assuming, of course, you plan to stay in the house for at least 5 years... if you don't, then I wouldn't bother.

 

[ddawg16]

I would NOT insulate.

As a native Texan, I know how the weather is down there.....It does not get really that hot....it's just the humidity...but in the shade, it's nice......and like you, I prefer to work with the doors open.....I like the fresh air......

I can't say I agree with using plywood instead of drywall......besides being more expensive, I'm not sure it's going to really get that damaged....if you are like most guys, there are enough cabinets and other stuff on the wall to protect them.

But I would suggest a good vent in the attic....keep the attic from getting too hot and the garage will stay cooler.

 

[kbs2244]

White roof and roof vents.
You need air circulation.
You said it your self.
You work in the driveway for the breeze.

 

[adpostel]

OK, so I took some measurements, and I dont really think I have the need to HVAC a 21 X 22 garage. Since there is a car in there and that is what I work on, I will most likely have to have the doors open if I am working on the car while its in the garage just for space issues. Is there something, like on a roll that I can just staple on the studs before I put the sheetrock on that will help keep it cool. I know that my roof is that radiant barrier stuff because I can see the foil on the decking from inside. Maybe just put in a large attic fan to create a breeze in there? Thanks for all the replies....

 

[dwilliams35]

I'm down here too; I've got 3 metal buildings out here: my shop and two farm barns. The shop is insulated, the barns aren't. The shop is quite comfortable in the heat of the summer: any breeze at all and you're good to go. The other two are pretty much unbearable sweatboxes during those months, no matter how much airflow you get through them: they've all got loads of airflow, but the heat radiating off the inside of the roof will just wilt you. The insulated shop is comfortable enough to just set up a chair in and have a beer in the middle of the day for the most part.l

 

[adpostel]

Good point DWilliams, I never thought about being able to pull the cars out and have a hang out in the garage, and that would be difficult to do if it was sweltering hot in there. I mean with me doing a whole makeover, we may want to spend some quality beer drinking time in there, poker and dominoe games etc.... Great point, so maybe I should insulate not so much for the working inside the garage as for just plain ole hangin' out in there too, huh?

 

[dwilliams35]

Well, one way or another: either be uncomfortable working inside the garage or uncomfortable sitting there with a beer. Take your pick: I'd insulate it in a heartbeat knowing what I know now after building my own shop.

 

[BWdiver]

I'm in the same position as adpostel, If I may (not trying to steal the thread) Add to, I live in central FL, Tampa area, it's hot and humid here also and I too Have worked in my shop thru two winters and one summer. the building is 30x40 2x6 framed with 11' ceilings with conventional trusses and skinned with metal, the only insulation is one inch board type with the shinny sides in between the roof 1x4 perlins, I have a 10x12 roll up door and 4 windows, its hot in the summer and cold in the winter.
BUT HERES my problem; I notice some leather pouches I have turn moldie, and my Harley motorcycle gets spots on the chrome which I believe is from moisture from the winter months and then it heats up during the day causing a drying effect.
there is no vapor wrap (Tyvek) under the metal siding, should there be? and if so could I add it on the inside then put my plywood up?

 

[bigdav160]

Just to expand on my point, here's an article from my local neighborhood paper:

Question: Should I install a radiant barrier in my detached garage to keep the cars cool?

Answer: A radiant barrier is one of the only insulation products that will work on a structure that is not airconditioned. In a typical airconditioned structure, we use insulation, double paned windows, and many different types of products to separate the hot from the cold air.

When dealing with an unairconditioned detached garage, the goal is to reduce the heat gain during the hottest part of the day and a radiant barrier will help keep the garage a little cooler.

Depending on how comfortable you want the garage, in addition to the radiant barrier, the use of fans will help cool your body, as your body is cooled by the air moving over your skin. My recommendation would be a wall mounted fan and or fans if you are using the garage as a workshop area.

Remember, unless you air condition something, it is never going to be cool, just less hot.

If you were to insulate your garage with a lot of the fiberglass insulation, by the end of the day, the heat in the garage would actually be trapped all day, unable to escape therefore making your garage hotter for a longer period of time.

Definitely use the radiant barrier in the detached garage, but also this is a good product for carports, covered patios, even horse barns, doghouses, or kennels because it will reduce the heat for the animals as well.

Radiant barriers have a great deal of applications, and are the only type of insulation product that will work with an unairconditioned space.

Remember, hot air will hold more moisture. Trapping that moisture is going to be bad for the building.

 

[BWdiver]

what I was asking was should I install the Tyvek, for a moisture barrier. not insulation.

Thanks.

 

[sneezer41]

Tyvek is not going to do you any good.

That article is bunk.

Insulate

Would you be more comfortable in an insulated or uninsulated house?

Garages aint no different

If you insulate well enough the thermal mass of the floor will keep it reasonable.

 

[sneezer41]

Oh, on the rust/mold, it is probably caused by the objects passing up and down through the dewpoint, causing condensation on the surface. control the temp, maybe even a dehumidifier and it will stop. Up Nawth we have the problem in the winter, cold objects as the air warms during the day

 

[dwilliams35]

One way or another, you're not adding moisture: if it gets hot, you're not going to magically manufacture water vapor: if you trap any heat, all you're going to do is lower the relative humidity on the trapped air. (that's a good thing) If you want to get rid of water vapor, you do it with air conditioning, not with "untrapped heat": Same reason I put a heater in my gun safe: I'm not removing any water vapor, just lowering the RH. Mold, etc. in a closed building is first and foremost a problem from a lack of ventilation: you don't seal up ANY building airtight. I have no moisture problem from an insulated shop: as a matter of fact, the converse is true in actual practice: if I want to keep something nice, that's where it goes. If I'm just storing stuff that I don't mind rusting, molding, etc., I put it in one of the uninsulated farm barns.

 

[kbs2244]

Ventilation is your friend.
Put in roof vents.
The humidity follows the heat out.

 

[BWdiver]

yep, I don't really want to insulate the whole garage, and I will add some roof vents this year, where the ridge vent would normaly be the builder put in a trans parent ridge for natural lighting during the day.

I wish I had them wrap it in tyvek at the least.

 

[adpostel]

Well I was talking to my buddy while sketching out the new electrical and air lines in the garage, and he feels that just sheetrocking, taping and floating the garage would provide a good enough barrier and prevent the garage from getting hotter in the summer and getting colder in the winter, does this sound right? Remember, it only gets really cold a couple of times a year in Houston, and I 99.9% of the time will not be working in the garage at those times, so there is really no need for me to heat the garage. The summer is a little different, but I will have the doors up when working in the garage in the summer. I guess, basically I am wanting the nice clean look of the sheetrock and paint scheme, and I am not sure I want the insulation to trap heat in the summer time since it is over 75 degrees 90% of the time in Houston, you follow me? Advice is well taken and appreciated.

 

[dwilliams35]

Think about it: what's insulation in a house do? It's just preventing the flow of heat from one space to another: in this case, the attic and the garage space. Now put a thermometer in the attic and one in the garage. Since they'll want to equalize within the parameters of stratification of heat layers in the space, the insulation isn't trapping heat in the living space, it's preventing the heat that's in the attic from migrating through the sheetrock, etc.. Unless you have no ventilation whatsoever, it's ALWAYS going to be hotter in the attic than the garage: trapping heat in the garage isn't going to be an issue here. Make sure you've got ridgevents and soffit vents to pull all the heat you can out of the attic, and then just make sure your ventilation in the "working space" is adequate enough to remove any ambient heat (that has made it through the insulation from up top). If I was doing exactly what you're doing here, I'd insulate the heck out of it, then install a whole-house fan in the ceiling: they make quick work of sucking out any heat that has built up below the insulation, and will provide a good breeze while you're working in there. (Gotta make sure you've got exhaust capability in the attic!!!) I've got the whole house fan in the house, and in the few times when I walked in and the house is way hot, it'll pull it down to the outside ambient temperature within a couple of minutes. It'll also blow the built-up hot air out of the attic and replace it with the "exhaust" from the garage space.

Also: today's nice and hot down here for a January morning: turn off your A/C for a few hours, then go in your attic and feel what's on the top of the insulation, then feel the top of the sheetrock underneath the insulation. Then tell me there's heat building up in the living space that the insulation is preventing from escaping.

 

[adpostel]

So dwilliams, your saying that you would go ahead and insulate the walls and sheetrock them, then sheetrock the ceiling and insulate on top of that, and install a fan that would **** air out of the garage through the attic, and ultimately through the attic vent?

I wonder if it would look too goofy to finish out the walls and not the ceiling? Anyone ever see that?

 

[dwilliams35]

That's exactly what I was saying: Whole-house fans used to be a MUST in Texas before air conditioning, and they're very underutilized now: they work GREAT. If you're not putting A/C in there, the wall insulation is kind of academic if you don't have full west facing wall or something like that. I'd go ahead and do it anyway; it's cheap enough, and if you ever DO put A/C in it, it'll already be in place without tearing anything out. One way or another, the absolute first thing I'd do is to put some green sheetrock on the ceiling with insulation on top. All else is just adding to the benefit. Back in my former life as an electrician, I've been in a heck of a lot of structures down here where the A/C hadn't been turned on yet, but sheetrock and insulation were intact: believe me, it helps a BUNCH.

 

[adpostel]

Cool, thanks so much for your advice and I will be following it. You've helped reinforce all the things I have read as they pertain to my situation. Now on to finding a whole house fan...thanks again.

 

[dwilliams35]

No problem: invite me over for a beer when it's done. The fans are pretty much always at Lowe's and Home Depot: hiding back in the back by the disappearing staircases and the roof turbines. Don't skimp on the louver that you get with it: the cheaper ones rattle when the fan's running. It shouldn't take much of a fan, though: these things move a BUNCH of air.

 

[adpostel]

I was wondering one other thing, what if I mounted the fan on the back wall of the garage, wouldn't that also draw the breeze through the whole garage. Reason I ask is because I have a limited amount of usable storage space in the middle of the attic due to the roof pitch, and I would like to be able to use it, If I put the fan in, it is supposed to go in the middle, from what I've read, and I just wondered about mounting it high in the middle of the back wall. Any thoughts...

 

[dwilliams35]

I guess it would certainly ventilate the space; the stuff you're missing is pushing the hot air out of the attic in the process. When I first turn mine on, you can literally see the hot air being forced out of the gable vents. It would take a different fan, though: you'd probably be better off with a power louver; the drop louvers that you use on whole-house fans will (and I know this from experience) flop around in the wind; pretty annoying. You'll also have waterproofing issues, etc. on a wall mount that you wouldn't have on the ceiling. On mine in the house, my plans have always been to build a little deck over the fan to get the storage space back (and to protect the fan itself): on my long list of undone projects. The whole-house fans generally don't HAVE to go in the middle: a lot of that would depend on just where the "makeup" air would come from: if you've got nothing but a single garage door, I'd put it as close to the opposite wall as I could get away with: if you've got windows you can open for the ventilation, that changes things. Main thing is just not to have real dead spots: 20' span over to an unbroken wall, etc.: they'll be out of the flow. Anyway: two main pluses I'd say on the inside one is the attic air and not having another wall penetration to seal up. I doubt you'd see much difference otherwise.

 

[adpostel]

once again to the rescue, great point on the water penetration issue on the back wall, although my home was built with these huge 2 foot eaves and that would help that situation, but then I would be missing the part of pushing the air out of the attic. OK, so now. I have one single whirly turbine on the roof right now, would that be sufficient if I turned on a whole house fan? And second, I will just mount the fan in the middle of the back wall on the ceiling. And by the way, I am having trouble locating a small whole house fan so far. The ones at the box stores all push a whole lot of cfm's, I would like to try to match the CFM's to what my whirly turbine can handle.

 

[dwilliams35]

Got any soffit vents? They'll discharge as well as **** in: if you don't have them, you need to put some in anyway!! I don't really know for sure how much air you could push through those turbines: I was kind of "blessed" with a couple of huge gable vents, so I certainly don't have the problem. I got mine from Lowe's as I remember: it's two speed: did you happen to see a low and high CFM rating? The low is pretty "gentle".