Basic insulation question

[FakeName]

Finally moving forward with my delayed garage project, and am putting together a budget.

The walls and ceiling space in the garage are completely uninsulated and bare. I've thoughtfully attached a couple images. It is my intention to sheetrock the walls and ceiling, but I'll obviously need to install some insulation.

So.

What do you suggest I use? Remember, this is a garage in San Diego, where it rarely reaches below 40 (WAY TO COLD!) and is above 80 only several days per year. I will be using a 2400 BTU (iirc) ductless AC system.

Of course, the killer blown-in insulation from a top-notch installer will be best, but may break my budget.

What would you suggest as a reasonable value for insulation here? Should the stuff go on top of the drywall in the ceiling, or attached directly to the roof?

Thank you.

The walls are 2x4 framed. I can only speculate why some previous owner painted the interior with silver- if I had to guess, it'd be a grow room. ; )

The exterior is stucco, and the garage is about 284 square feet.

 

[K'ledgeBldr]

...but I'll obviously need to install some insulation.

Why do you say that?
It's SD, man! And it's a garage!

The "ceiling" framing looks more like a couple of collar ties/ or drop beams with minimal joists or none. That means a lot of additional framing for hanging d/wall.
But, you could probably hang the rafters w/o additional framing- and if you do insulate, R-13 would be plenty. Just remember the baffles if you hang the rafters.

 

[Falcon67]

The most cost effective for your walls is going to be R-13 "batts in a bag". It runs about $60~65 and covers about 148 sq/ft of wall space. For the ceiling, blown is a little cheaper if you don't have to rent a blower. However, the space there looks pretty small, so laying out part of your ceiling at a time and back filling with R13 faced or unfaced at a minimum would work very well. you are going to want to get some kind of venting in that roof and the soffitts to move air above the insulation and vent the space. You don't need much more in that climate. I've had a building twice that size with R13 ceiling insulation and controled the internal temp with 12K BTUs in outside temps of 100+. Take care with the drywall and you could heat that thing with a cadle, should it get that chilly. You sound like Houston...LOL

 

[FakeName]

Why do you say that?

But, you could probably hang the rafters w/o additional framing- and if you do insulate, R-13 would be plenty. Just remember the baffles if you hang the rafters.

Help! I need an antidote!

Hang the rafters without additional framing?

Baffles if I hang the rafters?

Help?

(If you have any questions about photography, I can help you there...)

 

[Zeke]

He is talking about installing drywall against the rafters instead of a level ceiling. Baffles, as he calls them, are pans that allow air to circulate between the insulation and the sheathing.

I would not drywall the lid. Too much work. I would use a dropped ceiling grid (light weight) with flush light fixtures and insulation laid on top. You will need a couple of gable or roof vents above the insulation.

 

[FakeName]

Ah- got it.

Thank you.

I considered a drop ceiling with troffers, but was a little concerned about the loss of ceiling height.

Will revisit the idea, and thanks!

 

[GarageEnvy]

I'm north of you in Fresno where it does get to 110+ in the summer. I had the insulation/drywall debate and did it. I now believe it was the best money spent on the project. The caveat would be how tight the rest of your construction is. Mine was new and the vehicle doors were triple layer insulated so the space stays very comfortable. If you decide to go forward, call some contractors. My price with Lowes/Home Depot R-30 was about $2,500 for 1800sf with R-13 walls and R-30 in the ceiling. I had a contractor do it for $1,800 with R-38 in the ceiling and he caulked the sill and foamed all the wire holes and caulked between all the double studs. More importantly I never touched the insulation.

 

[FakeName]

More importantly I never touched the insulation.

This is good.

Thanks.

 

[ed_v]

My thought is it's San Diego..... Why do you need insulation?

Ed

 

[71flh]

From the looks of the 1st pic, you'll need to rethink the wiring before insulation. In fact, you certainly want to decide how to rewire it first. You'll be way happier if you do.

I'm not sure about the lightweight drop ceiling idea. Sounds like it won't be too attractive. I think it won't be very hard or expensive to put some 2x6 horizontal rafters in to support the future ceiling.

 

[FakeName]

Yes, electrical first is in the plans- but I'm better versed on electrical than insulation.