New garage and insulation question

[Chris Stack]

Have a new house and new detached 2-car, about 30x25. Living in Chicagoland obviously it gets cold here, and heat would be nice. POs were nice enough to insulate the garage walls nicely, and run a gas line to the far corner of the garage outside, so I’ll be adding a gas heater soon. They did not, however, put any wall coverings over the insulation, so that is step one for me. I am going to do it in plywood which I know isn’t “as good” as Sheetrock, but I don’t care, drywall is a huge PITA to work with and to work behind, versus plywood where I can screw into it anywhere, and I can just take a sheet off to run electrical, etc. Unfortunately plywood is stupid expensive right now, and hard to get, so I have to wait.

Here’s the garage in the mean time:

Cars by Chris Stack, on Flickr

My other question is what to do about ceiling insulation. The garage has an open ceiling with rafters that I’ve already used extensively for storage, so I don’t want to enclose the ceiling, I want to keep the storage. So that means some sort of insulation against the inside of the roof? Leaving an air gap? How best to go about this? There are three vents in the roof (one shown below).

Garage ceiling by Chris Stack, on Flickr

Appreciate your thoughts.

 

[jpaw]

I've been in your situation with your views but the best way is to to sheet the rafters and make an attic access. The lower ceiling height will make it much easier/cheaper to condition the space.
If you really want to leave it open you need to have ridge and soffit vents and with an air space between the insulation and the roof sheathing.
Also with a ceiling it will require a lot less lighting if you paint with a light color.

 

[Dragfluid]

And I'll say it again: The **** that gets thrown up on the rafters will still be up there 10 years from now without being touched. If you want a warm garage, sheet and insulate the attic. Otherwise, you're just ******* in the wind.

 

[The Cobbler]

effective attic ( ceiling) insulation is R38 plus.
by time you do that there's not much room for storage. I suggest putting up your ceiling and having minimum R38 blown in. put in a gable vent hatch that's removable for odds & ends of long stuff you want to store up there

 

[NUTTSGT]

Another vote for ceiling and insulation.

 

[kelpaso1]

And I'll say it again: The **** that gets thrown up on the rafters will still be up there 10 years from now without being touched. If you want a warm garage, sheet and insulate the attic. Otherwise, you're just ******* in the wind.

So true!

 

[mille755]

Cut one rafter, double it's neighbors, add a large attic access, sheet top of rafters in areas you want storage, hang whatever thickness of insulation will file with vapor barrier towards conditioned space, sheet ceilings. I think plywood/OSB is a superior choice for a garage or shop. You can hang anything anywhere. My shop was drywalled and I would prefer ply.

 

[mille755]

effective attic ( ceiling) insulation is R38 plus.
by time you do that there's not much room for storage. I suggest putting up your ceiling and having minimum R38 blown in. put in a gable vent hatch that's removable for odds & ends of long stuff you want to store up there

R38 is great for your house at 70 all winter or a full time heated shop. But for a homegamer, any insulation is a great and useful improvent over none. Just sheeting the ceiling will make the space habitable with a heater, insulation thickness is cost/benefit ratio that's how the code amount is determined, by what will pay off. Pay me now or pay me later. Compare R38 Insulating a house heated 24/7 to a home garage, you're out there at most 24 hrs on the weekend and 4 hrs every nite, so we will call that 2 full heating days compared to 7. Multiply 38 x 2/7 = r11. So I'd say anything above r11 for a home gamer garage would technically be overkill, not saying it isn't better just that financially, it probably doesn't matter. Any insulation is effective and adding more doesnt always make that much more difference, for a light use space. A

 

[Dragfluid]

R38 is great for your house at 70 all winter or a full time heated shop. But for a homegamer, any insulation is a great and useful improvent over none. Just sheeting the ceiling will make the space habitable with a heater, insulation thickness is cost/benefit ratio that's how the code amount is determined, by what will pay off. Pay me now or pay me later. Compare R38 Insulating a house heated 24/7 to a home garage, you're out there at most 24 hrs on the weekend and 4 hrs every nite, so we will call that 2 full heating days compared to 7. Multiply 38 x 2/7 = r11. So I'd say anything above r11 for a home gamer garage would technically be overkill, not saying it isn't better just that financially, it probably doesn't matter. Any insulation is effective and adding more doesnt always make that much more difference, for a light use space. A

I blew 19" of cellulose in the ceiling of my shed.
2368 sqft X14' and it gets heated with a 75k BTU hanging propane furnace.

Not one, single regret.

 

[spudley]

I blew 19" of cellulose in the ceiling of my shed.
2368 X14' and it gets heated with a 75k BTU hanging propane furnace.

Not one, single regret.

That's a big shed.

Really think you needed R-66?

And here I thought you Minny guys were tough. BTW, Bud Grant never heated his shed.

 

[Chris Stack]

For the short term, keeping the rafter storage is pretty important to me. I keep seasonal things up there, like my winter wheels for the S2000, golf clubs, kids’ sleds, and my collection of scrap lumber and conduit that I’m always pulling a piece down to do an odd job.

Longer term I need to build a shed and it can store some of that ****, but that’s at least a couple years out. If there’s not a simple way to insulate the roof rather than the ceiling, I’ll just go uninsulated for the short term, and then do a ceiling longer term. Plan is to keep the garage in the 40s/50s most of the time and just crank it when I’m working out there, which isn’t that often or that long.

 

[nadogail]

IMHO, Install a plywood ceiling in your garage with an access hatch. This will allow you to get into the attic so you can stash your summer tires when you shift to snowtreds.

Blow some insulation on top of your garage ceiling, Shredded Paper treated with boric acid is as cheap as you will find. After filling the spaces between the joists with insulation cover them with some floor boards, (I prefer OSB).

Any insulation is better than none. Everything is going to be a compromise between what you want and what you can afford.

My advice is guaranteed to be worth exactly what you are paying me for it.

 

[dcg9381]

Ceiling insulation is such a pain (unless you build an attic) - that the obvious answer for me us to have that roof deck done with foam... You'd need to plug the vent.

For the walls, I did OSB. Ply is expensive (compared to OSB) and you can get some structural support with it. From what I hear lumber prices are way up - so that may be a factor too.

 

[Dragfluid]

That's a big shed.

Really think you needed R-66?

And here I thought you Minny guys were tough. BTW, Bud Grant never heated his shed.

Kinda screwed up that size. Sqft x ceiling.
I like being comfortable. And I can't stand working in a coat. I don't need it 70, but 65 is nice. And the way it's insulated, it doesn't take that much to keep it there. (look at the build thread for more details)
I wanted at least R60, and with that much, you have to account for a little bit of settling, so that's why the depth.

Not sure what Bud did in his shed, but I'm guessing not plasma cutting and powder coating.

 

[mille755]

I blew 19" of cellulose in the ceiling of my shed.
2368 sqft X14' and it gets heated with a 75k BTU hanging propane furnace.

Not one, single regret.

I do not disagree, I was just offering a reasoned counterpoint to the "anything less than r38 is ineffective comment" all insulation is effective.

My dad's current shop is a 40x60x12 that is so over insulated, that he can cool it in the summer to 70 with a cheapie like 8k btu window unit. Probably has like you have r60 plus in the ceiling with a radiant barrier all around, foam and cellulose in the walls etc.
His shop before had only 1/2 polyiso nailed to the ceiling joists with r11 in the walls that one is home garage sized but can be made toasty in 5-10 minutes with a small propane salamander. It all works. And anything is better than nothing.

 

[spudley]

Kinda screwed up that size. Sqft x ceiling.
I like being comfortable. And I can't stand working in a coat. I don't need it 70, but 65 is nice. And the way it's insulated, it doesn't take that much to keep it there. (look at the build thread for more details)
I wanted at least R60, and with that much, you have to account for a little bit of settling, so that's why the depth.

Not sure what Bud did in his shed, but I'm guessing not plasma cutting and powder coating.

You peaked my interest so I read your thread. That's a nice "shed" and you do good work and a lot of it.

I chuckled at the home made rolling scaffold, and the cat walk as I also did both when my boys and I built our lake cottage (high vaulted ceiling).

Kinda bittersweet seeing posts by 1/2 cup...what a guy.

Great shop bud!
___________________

OP...even if you put up some 1" styrofoam panels as a temp ceiling (should be eventually covered by sheetrock) you'll be toasty warm. You got to watch out how much weight you add as I doubt those ceiling ties were designed to carry much.

 

[Dragfluid]

Thanks, Spud.
Yes, that scaffold was a joy to have. Could do so much stuff by myself when I needed to. It was a great workout for the body, too. The edges of the 2x's where the hands go to climb up are all polished smooth. LOL!
And I don't like people getting hurt on my watch, so I felt that the catwalk was mandatory. And it took very little to construct.

And Mille, my window unit is 5k.