Should I bother with ceiling insulation?

[dreygata]

So I was planning on insulating the ceiling of my finished garage (sheetrock on all walls and ceiling) by laying down rolls in the attic above it, but after checking my walls, I realized that the exterior walls of the garage aren't insulated.
So this calls into question whether I should bother with putting insulation in the ceiling at all if the entire garage can't be insulated.

My garage is about 20'x30', with about 35%-40% of the walls shared with the house (and thus insulated). I opted to have the garage doors (one double bay, one single bay) insulated when the house was built. For whatever reason, I didn't even think about telling them to insulate the exterior walls.
I do not plan on taking down the existing sheet rock to put up insulation, and I don't plan on any permanent cooling/heating systems in the garage.
Would putting insulation in the attic (I can pull up the flooring in the attic between floored attic and garage ceiling fairly easily) be a marginally beneficial endeavor, or would it significantly help?
I live in northern Alabama, so summer is more of a problem than the winters. I also work relatively often in the garage.

Thanks

 

[toyotadriver]

I would DEFINITELY insulate the ceiling even if the walls aren't. Since you live in AL, it gets hot in the summer.

If given a choice to insulate the walls or the ceiling, I would ALWAYS opt for the ceiling.

Plus, in the winter, heat rises so if you ever heat it, the heat is going to rise right out of the building.

 

[Falcon67]

Yes, lots of heat loss - and gain - through the ceiling. Our house garage has wall insulation and has only one - west - wall not part of the house. House stays at 76F during the day. There is no insulation over the drywall ceiling. The shop has R13 laid on top of the OSB ceiling. Both have 16' steel doors that face south with 1/2" insulation stuffed in them. No problem for the house garage to be 100F+ in the summer, shop might be 90 or a little more just sitting there closed up - and lots of times it's in the 80s if it's dry and "cool" - mid 70s - all night.

 

[ddawg16]

Hell YES.

One of the cheapest mods you will make.

 

[bczygan]

Please put your location in your profile.

Assuming that your location is a place with perfect temperature and humidity year round, and every hour of every day and night, then no. No insulation or heating or cooling system or dehumidification will be required.

Otherwise.........

Bill

 

[buddyboy]

YES... you have a lot of heat in that attic

heat doesn't rise (hot air does)

that heat from the attic will try to radiate down into the garage/house

the heat from outside will try to radiate thru the walls but the outside is only 80 to 90 degrees, that attic is easy 150+

keep your doors closed when garage is cooler than the outside temperature and open them when it's cooler outside

in the summer your blocking the heat from the attic from radiating in and in the winter your blocking the heat from getting out so by only insulating the ceiling and not the walls you'll notice the biggest effect in your summer months

your house will be easier to control too

 

[Chris705]

once you insulate your ceiling and feel how much cooler things are you'll want to blow some fiberglass or cellulose into your side walls....drywall in the garage couldn't be easier to core holes and blow it in....then seal up the holes.....

Good luck on your project....also make sure you have plenty of ventilation in your attic above the garage....either gable wall side vents or combination soffit vents and ridge vent. (when you add the ceiling insulation make sure if you have soffit vents you don't restrict the air and use plastic baffles)

 

[Falcon67]

Just got home, here are some readings: 98 in the shade on back porch. House garage is 96. Shop is 84.

 

[Voi]

I do not plan on taking down the existing sheet rock to put up insulation.

Would putting insulation in the attic (I can pull up the flooring in the attic between floored attic and garage ceiling fairly easily) be a marginally beneficial endeavor, or would it significantly help?

I suspect it will help significantly and I wouldn't bother with pulling up the flooring. Instead get an estimate for having insulation blown into both the exterior wall cavities and the ceiling cavities.

 

[WanderingSol07]

Yes, I insulated only the ceiling of my garage, stays warmer in the winter and much cooler in the summer.

 

[theoldwizard1]

HELL YES !!

Most heat loss (or heat gain in hot climates) is through the roof. Put as much insulation as will possibly fit, but make sure there is ventilation.

 

[86turbodsl]

I have data on this actually. The heat loss calculations i have run in the past (I am an engineer) end up being about 80% of heat loss is through the ceiling, and only about 20% through walls. If you put up a ceiling, and can't afford to do it all, do the ceiling first.

 

[Falcon67]

When Engineering says you're right, you're right.