Insulating the garage attic?

So now that its getting cooler, I am going to go back up in the attic to insulate the attic over the garage.

I do not care about cold weather insulation, only keeping the heat out of the garage. Living in Florida, I don't care at all about keeping the garage warm, only keeping the heat out.

Here is the setup... 3 car garage with a rather low ceiling. The rear wall is insulated and shared with the house.

https://sphotos-b.**.fbcdn.net/hphotos-prn1/76110_448460665754_1859616_n.jpg

The garage doors are insulated with the regular batt insulation. The left wall is concrete block and probably not insulated at all. The right wall is half insulated and half block un-insulated.

https://sphotos-b.**.fbcdn.net/hphotos-ash3/8427_133982920754_3077030_n.jpg

The attic is not shared with the house. Its completely seperate and sealed off from the house. There is no vapor barrier or insulation of any kind. The eaves are open or vented I guess. No roof top vent over the garage.

https://sphotos-a.**.fbcdn.net/hphotos-snc6/223042_10150159187170755_7505205_n.jpg

So do I need to install a vapor barrier or can I just blow in some insulation? I will probably go with the diy blown cellulose insulation because that appears to be the easiest way for me to get it done.

Also, would there be any benefit to insulating the concrete block walls with some rigid foam sheets?

1st question: Is the garage air-conditioned (or will it be)?

2nd: Can you post pics of your open (vented?) eaves?


My first impression (without benefit of the above info) is that blowing in attic insulation is what I'd do. I don't think that adding rigid or foam insulation to the block walls would help much since the trapped air inside the blocks can act as an insulator already. If those open eaves allow air into the garage attic, use vent chutes to keep preserve the airflow before you insulate and add some roof vents in the attic above the garage to let the hot air above your new insulation escape.

My .02 (and it might be worth evenb less...),
Paul

Here is a picture of the eaves. Its just perforated metal.



The garage has a heat pump water heater that does a great job of dehumidifying the garage and also cooling it down a bit, as well as a 1.5 ton AC unit that is run only occasionally to cool down the garage for projects etc.

Those eves will let out plenty of heat if the hot air had a way to get out.
You need roof vents.
They were probably left out for looks, but you need them.
The best looking over the big door would be a ridge vent.
A mushroom hidden behind the ridge over the small door will take care of that side.

Make sure you do not cover over the top of the eve vents with any added, or current, insulation.
But I would try venting before insulating.

I don't think I can add roof vents to the house. I don't want to go up against the HOA on that one, and I don't need to encourage my 12 year old roof to start leaking. The main roof has roof vents, but the one over the garage does not.

How about putting in a powered vent fan with a tube that ***** the air out of the highest point of the attic and then blows it out one of the eaves? That should do the job shouldn't it?

Do a thorough check of the HOA rules. I'd think you might be OK putting low profile static vents on the garage roof surfaces especially if the color was close or matched the shingles. Putting them on the side roofs so they don't face the street might also be acceptable. Can't imagine the HOA would baulk at you adding ridge vents, but I'm not sure there's enough ridge length over the garage to provide enough ventilation, it's not clear from your pics...

install shields to prevent the blow in insulation from blocking off the soffits, install a vent or two as close to the peak as possible and then blow in the insulation. I don't think the vapor barrier will be an issue as long as you aren't going to condition the space.

Dave

DPelletier said:

install shields to prevent the blow in insulation from blocking off the soffits, install a vent or two as close to the peak as possible and then blow in the insulation. I don't think the vapor barrier will be an issue as long as you aren't going to condition the space.

Dave

Click to expand...

The garage is air conditioned. I don't use it very often, but there is an AC unit in the garage that I use now and then when doing garage projects.