What is the insulation in the rest of the garage like? Is attached or detached?

@houssaon that info would help! It's an attached 3 car garage. Wood frame insulated house, has 2 impact low-e windows as well on one side. Back wall opposite doors is against the rest of the house. Garage is not temperature controlled.

Obviously R9 will be a huge improvement over what you have. If you can swing the R18 it would certainly add more value, and make the garage more comfortable.

@millworkman thanks, so big difference, worth almost 20% more in cost?

20% on 5K or 15K? If you do not work in the garage that often I would probably pocket the $ and go R9. But only you can truly put a value on this.

We went with r18 on our garage door even though it limited color choice and have no regrets. of coarse we also spray foamed our garage ceiling even though the space is unconditioned. Since our house shares two walls with our garage and we work out there sometimes we figured anything that helps is worth doing.

• We split the difference and went with a 13.45 R-Value with our new wood grain like steel doors. We also added Low-E glass windows for the doors versus the standard garage glass. Our walls and attic space, above the garage, are spray foam insulated. We share one wall with the house...it's the mud room. No windows in the garage, but there is an insulated door out to the back.

An R18 garage door seems extreme. Curious about how the manufacturer is claiming an R18 unless the insulation panels in the door are about 3" thick?

The answer to your question is "It depends." How do you intend to use the space and will it be conditioned? If the garage will be for storing cars and not used for much else, I'd spend the money on some shade trees instead. If you're going to use the garage frequently as a hobby/workspace and plan to condition the space, the extra insulation may be a worthwhile investment.

Depending on how the garage door is sealed,the 18R value may be overkill. Moisture and air infiltration around the door is a big culprit in temperature change.

I'd probably go with the lower and then go online and get some additional sealing kits for the top, bottom and sides of the door.

Thank you all! @just_janni that's what we ultimately decided, we will seal it up better once they are installed and go with the 9. We only use it as a workshop, for bikes and kid stuff and one side is a gym but we don't mind sweating a bit when working out. It'll never be air conditioned.

OK, you've already made your decision to go with the R9 doors (which is what I would have chosen, too). But, I'm wondering -- what is the weight difference between the two? I would think the R18.4 doors would weigh substantially more than the R9 doors, so you might need a more powerful automatic opener...