I worked for a worldwide insulation manufacturing company for 35 years. The code in FL is R30. There should be a sheet just inside your attic entry listing the amount of insulation installed when built unless some has already been added. I have about an R50 in my attic and I can tell you that you will feel and see the difference. Just be sure they install fiberglass and not cellulose which is fire resistant, treated paper. A great company and customer of mine was Suncoast Insulators in Ocala. They do mostly commercial but will do residential in TV. Very reputable honest people. Call them.

I insulated my doors and insulated the attic and it holds the heat in the garage.
If you want to cool your garage, Put it in a airconditioner

I understand and admire your thinking. I have two, cheaper, ideas that may appeal to you.
First, a whole house energy monitor. It's $299 and measures your usage 10,000 times a second. It uses this data to determine which appliances use how much. With this data you can make informed energy decisions. Do you know how much of your energy bill is for HVAC? I know mine.

Say, you've read that air drying clothes is the way to save the planet but you hate doing it, now you can know precisely how much you're saving. Leaving your Keurig on all day : bad idea? You'll know. Home - Sense.com.

The second tool is the black and decker infrared leak detector. Right now it's less than 30.00 on Amazon. With this you can see if your windows seal properly, is your garage door really a huge hot leak into the garage? You'll know with certainty. A FLIR camera is better but hundreds more.

What I have found: and you should listen to me because I am winner of RetiredGuy123's "I am frugal, but you're cheap" award for 2021; is savings come from fractional savings bit by bit.

I've found and repaired leaks at the solar light tube, leaks in attic ventilation junction boxes and so forth.

We used Solar guys. They did great job. Just did three months ago.

Would attic exhaust fans accomplish the same thing?

Attic exhaust fans can help by lowering the temperature of the attic, but the best you can achieve is to get the attic to the same temperature as the outside air. You still need an insulation barrier between the attic and the living space to slow down the rate of heat transfer between the two spaces. And, 12 inches of insulation is better than 6 inches of insulation.

Even if I know all these things where energy is wasted and explain to the wife she's doing things wrong and she should cut back,
I would be sleeping in that hot garage. :(

If not insulating the attic over the garage (a non living space) I would assume the wall between the garage and the house would be insulated. Do you know if that is a fact?

If the wall between the house and the garage is NOT insulated, there may be some benefit realized by insulating the garage ceiling.

Bottom line.....If you don't insulate the garage ceiling, (most contractors do not) it seems to me that insulating the wall between the garage and the house would be beneficial. Perhaps, more beneficial then insulating the the garage ceiling.

Adding insulation to attic
 

This has been a great topic with lots of input, which we appreciate since we're in the process of building a home and moving up from North Tampa to The Villages. After owning several homes, my wife and I discussed the need to insulate both garage attic, walls, and garage door, and our lanai on this new house since we're not so sure that the blown in insulation actually seals up all the areas in the ceiling, like gaps around pipes, canned lights, and other areas that can cause 'air loss'. We watched a few YouTube videos to learn do's, don'ts, tips and strategies before making the decision add extra insulation. We may spend a few $$ on this, but it gives us the opportunity to really inspect our attic/lanai areas and we're hopeful our efforts will give us piece of mind and some energy savings (if at all). Thanks again for everyone's input/perspective. It's been enlightening!

The wall between the house and the garage should definitely be insulated. This is a standard construction feature that the builder would apply to all houses. Typically, the builder does not insulate the ceiling above the garage, and it makes no logical sense to do that.

The monitor gives you information and that's it. The information cuts away all the disinformation away from the picture and let's you make intelligent decisions based upon facts. Not based upon opinions that "everyone" holds because it is "common sense". Here are a few:

1.electric tank water heaters waste huge amounts of electricity.
-they do not

2. Putting your water heater temp to 120 degrees will save you huge bucks (because of lower standby costs)
-patently false (you use more hot water when it's colder)

3. Your fridge sucks down the juice.
-no

4. A small instant on 180 degree water tap in the kitchen doesn't cost much, in fact it saves.
-costs more than you think, no savings

5. Insulating your attic to R50 will save you big
-no

6. natural gas is good because it saves you so much.
-the meter and customer fees are so high that you are better with all electric unless you are heating a pool.


I make decisions on habits and appliances based on the full knowledge of the cost to operate, not the opinions of some nameless yahoo on a forum. Sometimes I use electricity in some way that 'everyone knows' is wasteful because it costs so little and the convenience is well worth it.

Get several quotes. They will vary significantly.

If adding initial insulation to the garage or lanai, you also need baffles along the soffit. Some quotes may not include them.

Solar attic fans may not cool the attic effectively. Often placed next to an existing open vent, it pulls air into the attic through what should be an exhaust vent, and then discharges it. Net effect close to zero. Be skeptical of pretty pictures with big blue and red arrows. Air flows the path of least resistance.

An electric powered attic roof fan moves a lot more air. The often cause the interior of the attic pressure to be a lot lower than ambient. That can pull air conditioned air from inside your house into the attic via cracks, gaps, outlets, exhaust vent holes, HVAC pipe holes. etc. That forces replacement air to come in from hot outside air. Net is a hotter interior. Every house is different.

R38 is now the standard. That is roughly 12 to 14 inches thick of blown in insulation. At that amount, adding more still improves overall, but it is a small amount. At today's energy prices, typically not cost effective. What tomorrow's cost will be are harder to know. It's known as diminishing returns. If R50 is better, then how about R80? Or R125? There is a point when the cost to do something is more than the benefits it causes.

Insulating a garage does not "cool" it. That is a badly worded conclusion from using incorrect terminology.
In the summer daytime, heat moving downward from the ceiling warms the space. Insulation in the attic prevents radiant heating in the day, and also blocks radiant cooling at night. Garage (without AC) will never be cooler than the outside temperature, except in the early morning when the quick rise in outside temperature is faster than the static temperature of all the stuff in the garage that cooled off overnight. Insulating the garage causes the inside temperature to stay more steady. The may or may not be cooler, depending upon the season and time of day.

If the garage door faces north, away from the sun, insulating it may do the unexpected. On a warm day, when the ceiling is radiant heating the garage (say to 100deg) from a hot attic, and the outside temperature is 85deg... then the garage door surface would be cooler (near outside air temp) than the interior garage temperature. That large cool panel is helping keep the garage cooler because it does not have insulation on it.

If heating or cooling a garage or lanai, insulate it.

Looking at temperatures with an IR thermometer sometimes gives false readings on metal or glass surfaces. They reflect similar to a mirror. That issue can be seen easily with a thermal image camera.

So beware of generalized recommendations that are not correct in all situations.

Whether your exterior wall is insulated depends on if you have stucco or vinyl siding. When installing the stucco, they use concrete blocks and polyiso foam insulation with a foil sheathing. The entire combination of the concrete, stucco and the foam insulation should total R13. That is the code. If your house is vinyl siding then they use a felt black backer board and in between the wood studs they use R13 fiberglass. Not sure now if they are installing the foil backed polyiso sheathing or not.

Very well explained, Thanks

This is an outstanding thread full of useful insights, advice, and information. I recommend it be made a "sticky" or somehow added to a "common knowledge" thread.