Insulation choice for garage ceiling?

[dreygata]

Hey guys, I'm new here, so I apologize if this has been done to death.

I have an attached 3 car garage that I work pretty often in. It's about 20ft by 30ft with two windows and insulated garage doors (one double bay, one single bay). It already has sheetrock on the walls and ceiling. Above the garage is uninsulated floored attic storage accessible from inside my house. I have no active heating or cooling sources for the garage.

I live in Alabama, and I want to do what I can to keep the temperature down in the summer so I can work on my bikes in relative comfort. I'm fairly certain that the walls have insulation in them (two of them have to since they are attached to the house), but for whatever reason, there is no insulation between the garage's ceiling sheetrock and the attic's flooring.

I feel that putting insulation there would be a huge help in reducing the amount of heat that gets into the garage. However, if I wanted to use rolled insulation, I'd need to pull up the flooring, which isn't too much of a problem, but it'd be a PITA and just take more time. I could possibly stick a hose for blown-in insulation along the sides under the flooring (the cavity isn't 100% sealed off), but I have no idea how many bags I'd need or if it'd be any easier.


Any thoughts or suggestions? I figured if I did rolls, I'd go for R-19 or R-30 unfaced insulation (I have 2x6 joists).

Thanks!

 

[NUTTSGT]

You're probably on track with pulling up the attic floor. I did something similar in my garage....pulled up what floor was there, put in rolled insulation and topped it with sheets of insulation between the joists. I used mini rolls so I had to cut a half section between each set of joists. There's pictures in my refurb thread, link in sig.

 

[Falcon67]

I put R-13 faced in my shop because it was on sale and I may come back later and add more. Budget thing - better to have all R-13 than half R-19 and half none. It's been good enough so far. I installed after the ceiling was in.

If you work at it and maybe pull up just some of the floor, you can "fish" the roll insulation under the flooring. I have 8' wide OSB decking in the shop attic and was able to push the roll insulation under the decking from the open sides using 1x2 push sticks of various length. Not fun but can be done. R-19 should be pretty easy with 2x6s.

 

[UpNorther]

Any thoughts or suggestions? I figured if I did rolls, I'd go for R-19 or R-30 unfaced insulation (I have 2x6 joists).

Thanks!

Too much insulation is just as bad as not enough. For a 2x6 depth the max you can put in is R21. Forget about the R30 idea.

The easiest thing would be to blow it in. The bags of insulation will say how many square feet they'll cover at what thickness. Underneath your flooring just shove the tube in a little ways, tape it to a stick if that helps.
If your going to actively be up there, rolled insulation might look better though.

 

[aircommuter]

That is correct about the r21 limit for glass, however if feel you need more value you can get 4" foam sheets that will r-30 or more.

 

[dreygata]

Thanks guys. I was looking at fishing fiberglass through so don't have to take all my attic junk out.i think I can swing getting R21, though I might stick with R19 depending on cost. I'm never going to install any permanent heating or cooling, so I'm not too worried.
It's a low priority for me at the moment (budget reasons) but I do think it'll help the garage be more tolerable.