Dumb, basic insulation questions...

[TheOtherGoose]

I'm thinking of making my attached two-car garage a bit more hospitable during the winter months. Currently, the three exterior walls and ceiling are uninsulated. Exterior wall material is brick on all sides with drywall in the garage.

I'd like to be able to make it warm enough (maybe 50-55 degrees) where I could do an oil change without freezing during a Midwest winter. The insulated garage door is relatively new and doesn't leak air. The garage volume is 20'x20'x9'.

Would it be a waste of time/money to insulate the ceiling with some R-30 fiberglass and leave the walls alone?

I'd like to be able to get one of those ceiling-mounted 240V heaters that put out about 17K BTU's to achieve my heating goal.

With R-30 in the attic, could a heater of this type/size be able to get the temp up to ~50 degrees and maintain it when it's 20 degrees outside?

I'm just trying to see if this would be worth doing...

 

[pattenp]

Since most of the heat loss is through the ceiling it will be better than nothing. I think the 17K BTU should keep you warm with only the ceiling insulated.

 

[Gary S]

The ceiling insulated would be a great start as most of the heat goes up and wants to escape up there, but you still have only half the job done.
Why not rip the drywall. Is it useless in a working garage anyway. Then add 2x4 stud walls inside the brick and insulate it properly with nice R13 blankets. Then cover the insulation with OSB or something suitable for a work environment.
Then you have a building that (without adding heat) will keep itself 20-30 or more degrees above outside temperature all the winter, and 30-40 degrees cooler than outside temperature in summer. Think about how much heating bill that saves you.

And whatever heat or cooling you add after that stays in there a lot longer so you pay a lot less in the long run.

 

[paullie]

it would be better that ALOT of houses are insulated, go for it

 

[thammel]

I have the exact same situation and I went whole hog and did it the right way:
1) insulated both garage doors with foam panels cut to size from home Depot
2) ripped down the drywall on the uninsulated walls
3) installed more receptacles on those walls.
4) Insulated the attic and while I was at it installed pull down stairs and some flooring for very light storage up there. Also installed a few lights up there and a receptacle,
5) Now insulated the previously insulated walls.
6) Put drywall up over the insulated walls
7) Primed and painted entire garage
8) Also put in some switched ceiling receptacles for hanging fluorescent lights.

I will say that one small 1500 watt electric heater now does a fine job of keeping the place warm enough. Ceiling insulation will help. Also, be sure the doors are insulated. After that, insulating the walls will help.

Tom

 

[TheOtherGoose]

Thanks for help, guys. I agree that ripping the drywall off and insulating is the way to do things properly. My wife would probably kill me, though, since this kind of project is considered a luxury. She's rolling her eyes at the idea as-is.

 

[pattenp]

Thanks for help, guys. I agree that ripping the drywall off and insulating is the way to do things properly. My wife would probably kill me, though, since this kind of project is considered a luxury. She's rolling her eyes at the idea as-is.

Don't you just hate it when they do that. Do a cost benefit analysis. You need to out think her.

 

[Plump]

My entire garage is pieced together with beg/borrowed/stolen supplies. This meant that I was unable to do everything at one so the ceiling insulation was a priority. It made a huge difference for the propane heater that I had at the time. Could totally raise the temp and not have to run the loud son of a ..... at full bore the whole time. In my opinion, totally worth it.

 

[jvitez]

I'd use R40 in the attic. Lay R20 batts in the truss/joist spaces, and lay another R20 perpendicular to this.

The best insulation is blown in cellulose for an attic. Is there an access hatch from inside the garage? If so, consider blown in insulation. Also, make sure to weatherstrip the attic hatch tight. You don't want warm moist air condensing in your attic.

I'd insulate the attic to R40, install your heater and see what happens. You can always supplement a 240V heater with a plug in 1500 W heater of you choice, or even two if you have two separate 120v circuits.

If it ***** too much power, or still feels cold, you can always add wall insulation at a later date. Insulating the ceiling and adding one 240v heater won't seen like so much work and expense to the Mrs.

If you do want to insulate later, look into simply glueing foamboard to the existing drywall, and drywall over the foamboard. You don't need to tear out the existing drywall. Foam board eliminates building a stud wall, and you gain insulating value by not having conductive heat loss at ever stud.

 

[TheOtherGoose]

Again, thanks for the information. I appreciate it.

I've ordered up some R30 roll-out insulation. Since I've got a tiny little car, I'm paying Lowes to deliver the 16(!) rolls. I've really been selling the idea that the whole process will happen in the garage (no mess) to my wife.

I'll be interested to see how my little 120V/1500W heater does after the insulation is installed. Such experiments are all part of the hobby, I suppose. I'll let you guys know if the ceiling-only insulation helps at all.

 

[NUTTSGT]

Just doing the ceiling will help, get the walls done and you will notice it even more. Insulation is an investment, you'll get a return on your investment.



Think of an attached insulated garage as an airlock. Ever walk into a business that has the double doors when you enter ? That small separation helps keep the heat/AC in. Having your garage insulated will help create the same effect, when you go outside in the winter, the cold air that rushes in won't be as cold as the outside air.

 

[WanderingSol]

I have a 24' x 24' attached garage with 9' ceiling. Side walls are exterior, one wall common with house and two 7' x 9' doors. Doors are new a couple years ago, steel with insulation and very good weather stripping. But the garage would still get below freezing or very hot in the summer. Two years ago I put 6" batts (unfaced) in the attic over the garage space. Now the garage has not yet gone below 32 degrees or over 90 in the 100+ summer days. My drywalled walls are not insulated. It was well worth the $200 to insulate the ceiling. I'm north of Indianapolis so I am NOT in a warm winter climate!

For the walls I still think of some rigid foam on the inside would help, but it probably would not be safe in a fire situation.

 

[TheOtherGoose]

It's good to hear that your insulation helps maintain a reasonable temperature. If the ceiling-only insulation idea doesn't work for me this winter, I'll 'fess up.