NA -- Garage Insulation / HVAC Question

[JGoodish]

Already posted this in a garage build forum, but thought I'd take the pulse of folks here.

I live in PA and have a detached garage which I'd like to insulate and heat. Right now I have 100 amp electric out there, but no gas.

The stats:

-> 24x26 exterior dimensions
-> brick veneer exterior, all above grade
-> 2x4 stick framed walls, 2x8 framed ceiling and roof
-> 8.5' floor to ceiling height, attic floor above
-> one insulated man door, two 9x7 insulated (2") garage doors
-> two small windows, double-pane

The interior is presently unfinished, and I am preparing to insulate it before the colder temperatures arrive.

Ceiling insulation options I'm considering:

1 -- Unfaced R30 batts + 1" XPS or PolyISO + Type X drywall. That would give me ~R30 or so in the ceiling (I'd lose some R-value under the attic floor since the batt would be slightly compressed in that area).

2 -- Blown cellulose + 1" XPS or PolyIso + Type X drywall. Should give me the same ~R30, but might be tricky to ensure adequate distribution of the cellulose under the attic floor.

3 -- Blown cellulose + Type X drywall. By my calculation, probably less that R30 with the same distribution concerns as option 2 above.

I could pull up the attic floor to ensure better distribution of the blown in stuff, but that would likely require unloading part of the attic, which would be a pain for seemingly questionable benefit over batts in my situation.

For the walls, I was planning on R15 kraft-faced batts.

I am skeptical of the ROI for spray foam in this application, and for that reason am not presently considering it as an option.

Also, I was planning on the electric heater route for warmth, but am now wondering whether a mini split would be worth the investment given the additional efficiency that it would provide. Not sure of required sizing for this type of a space given my insulation plans. If someone tells me that electric heat via any option isn't a great plan, digging a trench for gas is an option but one which I had hoped to avoid.

Any thoughts and feedback would be appreciated.


Thanks,
JKG

 

[Clark1961]

Dig the trench for the gas line....but then again I produce gas for a living...

 

[cowman]

If you're like me you will probably leave the heat off when you're not in there. In that case you're going to want something that warms everything up from cold to warm quickly and that's going to be gas.

Now in my case I'm putting in a forced air wood burning furnace for my 36x50 building but I don't have gas service here and I have all the firewood I can cut for free.

 

[iRyan]

I have a spray foam company in NJ & PA but we do some batts too. Shoot me a pm of you have foam questions or insulation questions too

 

[ChemGuy]

If you don't want to spend money on all spray foam, look at "flash and bat". An inch or so of spray foam to seal the building and the bulk of the insulation value is in Batts or blown.

Even with tyvec wraps, etc there is a lot of leakage. Foam seals that up.

And blown cellulose in attics is a pain. Mine has settled a bit over 30 years.

 

[Norman]

Dig the trench for the gas line....but then again I produce gas for a living...

 

[Shawn]

Are you looking for constant climate control round the clock or to make it comfortable just while you are working out there?

If the latter...have you considered a small wood pellet stove? Heats up FAST and can shut down with a flip of a switch. Typically they can be ducted right out the side wall so no need for a riser flume. Would probably be your cheapest installation and operation cost.

I agree any electric or gas systems are gonna take a while to even take the edge off if you are starting from ambient temperature inside on a frigid day.

 

[Craig]

One question no one asked...what are you going to be doing in there? If you are going to have tools and machinery, then you are going to want to keep it warmer and drier than you think, so that you do not have a rusting problem. That's going to mean constant climate control during the winters. You will want to keep it above about 55 degrees and around 50% humidity to ward off as much flash rusting as possible. Hot and cold cycling the air and not maintaining a lower enough constant humidity and you will be battling rust all winter.