need help insulating

[godtar]

I live in MN.
3 car stand alone garage with a 14 foot door at one end. 2x4 walls, no wrap on outside.

My plan is as follows...

1) R15 BATT INSULATION IN WALLS R-15
2) 2 INCH FOAM SHEET ON TOP OF THAT R-9
3) 1 INCH FOIL FACED FOAM SHEET ON TOP OF THAT R-6
FOIL SHEETS ARE TAPED TO PROVIDE VAPOR BARRIER
4) TOTAL R FACTOR FOR WALLS R-30

5) I HAVE AN INTERIOR WALL ISOLATING THE GARAGE DOOR

STEEL RIBBED LINING ON TOP OF FOIL INSTEAD OF SHEETROCK

CEILING IS BLOWN IN 30 PLUS R VALUE

THOUGHTS????

THANKS,

DOUG

 

[Dragfluid]

Since you don't have it wrapped, have the walls dense packed with cellulose! It's cheaper than fiberglass, and more effective. And it will stop air flow. Then put your foam over that.
Put 18" of cellulose in the attic, so when it settles you'll have 16" for R-60. Be sure to seal up all of your ceiling penetrations, also!

You can do the dense packing yourself, if you can get ahold of the right machine. (Force 2 or Kendl 425) Both rental machines. Anything less isn't powerful enough.

Where in MN are you? I'm in Dayton.

 

[Voi]

My plan is as follows...

1) R15 BATT INSULATION IN WALLS R-15
2) 2 INCH FOAM SHEET ON TOP OF THAT R-9
3) 1 INCH FOIL FACED FOAM SHEET ON TOP OF THAT R-6
FOIL SHEETS ARE TAPED TO PROVIDE VAPOR BARRIER

I like the idea of using cellulose and also taking time beforehand to do a good job of caulking seams. Maybe it's unnecessary with wet pack cellulose, which is said to have good air sealing properties, but I'd at least get areas like where sill plate meets the floor, etc.

The fact that you'll have a wall to seal off the overhead door suggests you're really wanting a tight space so I think some caulking is worth your time.

I just looked up the price of 1" foil faced polyiso and it was $23.56 at my local Menards. I assume the 2" foam is the pink or the blue stuff and around $30, so you're thinking around $54 or every 32 square feet?

I'd consider going with one of the fiberglass faced polyiso sheets at Menards and just doing one layer of foam. They can order it in 1" to 4" sheets in half inch increments.

The three inch, for example, is $37.49 so quite a bit cheaper. And you'd have that layer of fiberglass for a bit more screw bite with your metal walls. I'd double check to make sure it's up to the task but it's made for roof decks so I assume it has some nail holding capacity.

https://www.menards.com/main/buildi...-decking-insulation-board/p-1444438918055.htm

If you were thinking of strapping over the foam for the metal maybe the fiberglass layer would allow you to skip that, I don't know. But again the fiberglass would give some bite for the screws holding up the strapping too.

If you really wanted the radiant barrier you could look at some of your options for the roll type options. With your 50 cent per square foot savings you should be able to get something. And it would act as a vapor barrier. A quick check says Reflectix in the 100 foot roll is right at 50 cents per square foot at Menards.

 

[DC73]

Department of Energy minimum recommended ceiling r-value is R49 for the southern half of your state and R60 for the northern half. More wouldn't hurt, especially if the price is right.

DC

 

[wagspe208]

What is the SF cost of all that? Foam board is expensive.
I had closed cell sprayed on the walls. At 1.5", it is air tight. Closed cell is a moisture barrier. Bonus is, the **** is strong and ties everything together a lot.
I think I paid 6k to have my walls done. 50 x 72 building with 12' walls.
It is really amazing. I can put my hand on the foam inside, and it is not hot/ cold to the touch at all.
I was concerned about the cost... but it is worth every penny.
ESPECIALLY sealing all the air gaps. This is the big issue in pole barns.
Wags