Thanks for the tip, i’ve never seen or heard of the reflectix, but it has lots of possibilities.
i bet you don’t need much light in the death rocket garage either. 
And damn Dr evil, is R-90 really a thing? How is that done?
It has so many possibilities,.
I even use it for packaging, ice shanty floor, bunny habitats, even an extra layer in the bottom of ice boots…
In the garage it mostly slows air flow. Radiant reflectivity helps, but mostly traps air. low R value, but that still saves so much fuel.
There are so many lights in my garage. Not good ones, mind you, but very many. I think about 60k lumens. Next time I will take a pic.
I have been watching building science evolve since the 70s. Generally more insulation is better. Vapor barriers are where it gets tricky. Depending on your climate it can be on the outside or the inside. Usually on the warmer side. Don’t want rot forming in your walls. The latest code is calling for extremely tight building envelopes. Mechanical ventilation is required to get fresh air in. The book is still out on a lot of this.
That’s what i was thinking—that it would help lighten up a dark garage or attic area.
It sure did! Allowed me to just use led bulbs with no fixture.
I have a small garage, usually i leave doors open in summer to avoid car engines heating air that then leaks into the house.
In winter i will close doors to keep cold air away from house doors and car engines.
They are not insulated.
The garage is too small for me to ever use it as a work space, so I do not need to heat and cool it.
I purchased the low-tier of insulated garage door, I think R-9 or R-13.
Two walls are cinderblock, the ceiling and third wall are insulated with poorly installed drywall. It faces north.
I don’t have any measurements, but the water in the sump didn’t freeze the winter after it was installed.
One thing to remember about R values in these doors is that an R12 is not twice as much as an R6.
I found this chart. Not for doors, but at least gives some comparison.
That shows relative amounts of heat reduction.
A single ply metal door has an R value of 0 according to one source I found.
So any insulation will make a big difference.
One of the unexpected benefits is how much quieter it is inside with the doors closed. A pleasant surprise.
I went with the belt type openers instead of the chain. Much quieter too.
I need to add lighting.
Any of you have some suggestions as far as shop lights for a garage?
All the Best,
Jeff
If you just want to retrofit and existing socket this style is bright as hell. There are others in the Vipon deals.
Another thing that really helps is the newer Weather Strips with the rubber that seals against the door —- Plus a good bottom Rubber that’s not all shrunk up several inches on each end— But I would advise if you keep vehicles — anything that makes carbon monoxide — Have a good Sensor located in the garage — you don’t want to wake up dead
The R value of insulation is the Resistance to thermal energy transfer (mainly conduction). It is additive in that 2 layers of R-6 will give you an R-12 rating.
For example with a given amount of heat or thermal intensity such as from the sun hitting a metal garage door skin, if an R-6 layer will provide a 6 degree temperature difference, then an R-12 will have a 12 degree difference for that same heat flux. Same sized door, same sunlight, same amount of time exposed.
It is similar to electrical circuits where the temperature is ~ voltage, the R-value is the resistor, and the heat flux is the current flow. Double the resistor and current is halved, etc.
Adding any insulation helps a lot, if done well.
You can see my cheap lighting solution. I would not recommend it as is.
Cheap as can be, I just wired in new bulb bases off a ground fault outlet, then used cheapo Y sockets to put 4 or more bulbs in every one. They seem stable now, but when I first did it, a few of the Y adapters made a crackling sound in use and looked like they were arcing on the contact points. Dangerous.
If I were to do it again I’d still use bulb bases (cheap upfront, easy replacement), but instead of 4 rows of 3, I would double at least double the number of bases.
LED shop lights would be nicer, but at the time they were a lot more money for same lumens. I also get to try different bulbs or easily upgrade (already went from 60w to 100w equiv and moved 60W to basement).
Re: adding more insulation…. There are diminishing returns when adding more R-value.
This article a good information source
For lighting, I’ve used Costco’s led shop lights. Whatever was cheap at the time.
From a theoretical academic standpoint he uses just one equation for a side wall to base all his economic conclusions, but not one word about the temperature difference expectations across the various insulation thicknesses, [nor the fact that heat loss is mostly vertical, nor the effects of direct sunlight on a metal garage door.]
Seems to me that’s what really matters—if its 95 outside and you want to be 75 inside, then that 20 degrees has to come from either thick insulation or running the AC, which costs more?
Same with heating in the winter, if its 20 outside and you want your wife to be happy, then you need to make up the 55 degree difference, either with extra insulation or running the heater.
I will tell you what else matters. If that temperature differential between periods of time is close enough and substantial, the plastic containers of liquids that you store high will eject liquids, even unopened.
Not fun with brake fluid.
Yes One thing leads to another—now i have a dozen plastic bins to put on the shelves to hold the cans of unopened liquids prone to self destruct and leak. Learned that the hard way too. 
Kennybobby is on point about insulation vs AC. I sized my mini-split to what I could best guess as far as the non-insulated doors and highest indoor temps reached (120F+). If I can find an old temp log, I’ll POST it.
After talking to the AC guys - they were at first thinking 1.5 Ton. We went for a 2 ton unit.
The thing is a variable speed compressor, so it will ramp down if max cooling is not needed.
Had a few super hot days and with the thermostat set for 68F. I wanted to see if the thing could hold that temp during peak heat time. It almost could do it. Inside temp just went up a few degrees. This would give me a good idea of what temp settings would be most beneficial Temp vs run time wise.
Also turns out I didn’t have the settings optimized. RTFM!, so maybe it might have done a bit better. But don’t think I was off by much.
With the new doors, I haven’t had a super hot day for testing. But best guessing, I think the max inside temp with the AC off would end up in the mid to high 80s - maybe low 90s when it’s really cooking outside.
The AC should have no problems keeping up with that. No matter where I set it.
Now as far as energy vs $$. You can buy a heck of a lot of KWH of angry pixies for what a new set of doors costs. Payout will not be in my lifetime (old fart here).
But I needed new doors and openers - the old doors were getting way cranky. This happened not long after I got the new AC installed.
So I felt it was worth the extra bucks to get the best I could reasonable afford.
I’m glad I did. The quality is way nicer than the single ply doors and the added quiet operation and exterior noise reduction is much appreciated.
I’d make the same choice without reservation if given the same conditions.
I’m looking forward to not having stuff in the garage die premature deaths do to super high temps (including me!).
All the Best,
Jeff
It’s funny how often you hear folks talking about insulation…
” i put R-30 in the attic, but i wish i had only put in R-16”
or
“i sure miss paying a higher bill for my utilities”