Hot down here bubba. Of course S.C. is always hot in the summer. I have remodeling job with a due west facing garage door and no ceiling in the garage or insulation. Two gable vents. What’s the best way to insulate the garage to prevent heat from going inside the house? I say drywall the ceiling to firecode, install R-30 insulation in the ceiling and attach foil foam on the interior of the garage door and install a thermostatic gable vent fan. Is this too much or not enough? Please respond.
Thanks, Pikster
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add radiant barrier to inside of rafters.
forget the attic fan.
Otherwise your answers are good.
paul42,
Please explain the radiant barrier trick and who manufacturer's it.
The shingles are heated by radiant heat from the sun. Most of the structure heat gain is by radiant heat from the roof sheathing. Some is carried by the hot air, but most is radiant.
Anything that reflects heat well, is also a very poor emmiter of radiant heat.
Home Desperation sells a product called solar shield. It is perforated paper/foil on a big roll. The foil side goes down, to keep dust build up off the foil side. It is stapled to the underside of the rafters and will keep the attic noticeably cooler.
There are radiant barrier paints that also work - just not as well as the foil. But, the paint can be easier to install depending on your application.
There are several other radiant barrier products, some of them in the form of bubble wrap that claims to work better. I'm not convinced their claims are true yet.
Curious about the radiant barrier does it "cook" the roofing more but reflecting the heat back at the sheathing/roofing that would otherwise be dissapated over the attic air space?
The color of the shingles has more of an effect on their temperature.
The radiant barrier raises the temperature of the shingles by 2 or 3 degrees.
Most of the heat from the shingles is actually radiated back towards the open sky - even in full sunshine.
I read an article that said the ability of white shingles (i.e. composition) to reflect solar gains is negligible over e.g. black or dark colored. Primarily due to the texture, I think. I think this is a little of what a prof once called a hot white/cool black phenomenon ... the irregular white reflects heat into the material rather than away ... gathering solar heat rather than reflecting it. He created a solar collector panel using this theory ... and it generally worked.
Dunno about the theory, but there's pretty good anecdotal evidence that light-coloured asphalt shingles last longer than dark-coloured ones. Sure they're not a planar surface, but a good fraction of the surface of each shingle is the granules, and a good fraction of the surface of each granule is pointed away from the roof. The colour of the granules, or more properly their emissivity, must have something to do with the temperature and hence the durability of the shingles.
I was up on my roof last night replacing a plastic vent that the squirrels went to town on. Chewed it literally to rat sh*t, then were in my attic chewing up my Icynene. At least now I know where the b@stards were getting in- it was not visible from the ground. Why the hell they'd want to be in there in the summer baffles me- winter I can understand! Want them dead, though- squirrels are rats with PR! Replaced with metal- let them blunt their teeth on THAT! And the plastic and aluminum ones were the same price at the local building box- go figure.
Dunno about the durability of one color of shingle over another ... I read an article once that basically said ... from an energy/heat gain standpoint, light colored shingles did not reflect heat SIGNIFICANTLY more than e.g. black or dark colored. There was a difference, just not much ... not enough to have that aspect sway which shingles to buy ... buy for looks/color, not energy.
is this your question ?..
<<< What's the best way to insulate the garage to prevent heat from going inside the house? >>>>
or do you really want to insulate the garage ???
if you want to stop heat from the garage going into the house insulate the wall between the garage & the house...
is it a 2-story house & a 1- story garage ?
then insulate the entire common wall
if you really want to insulate the garge, then that's going to need a different solution
MikeSmith,
The original question was for the garage, but I failed to make that clear. We're in the process of insulating the garage. Yesterday the temp in the garage attic was 142°. If I can find the reflective foil that Paul42 suggests, I'll use that also. Thanks for the input.
Pikster.
i'm not fan of reflective foils.....
i'd do as you said... install a ceiling and insulate the attic....
only i'd use cellulose.... & forget the power vent ... i'd use soffit vents & ridge... or soffit vents & a gable ventMike Smith Rhode Island : Design / Build / Repair / Restore
Does the door have windows in it? Is the roof shaded? How about the door in late afternoon? Is the door insulated. Need a little more info, man.
The Garage door is an double 16' directly facing west and no insulation. There is no shade and it faces directly west. I have insulated the door framing 24" on each side of the door and installed drywall. From the door top to the roof soffit is 43" and it's all insulated and now sheetrocked. I's like to put foil panels on the door panels, if that would help. Anything to get this garage cooler!!!
Not knowing other particulars about your situation, I'd insulate the door to the max. If it is a metal door, you should be able to buy rigid insulation thickness to match the door structure thickness. Right now it tends to be a bit of a solar collector ... even if painted white. FYI The insulation may affect a little the spring situation due to the additional weight (which is small, but the door was installed in somewhat of a balanced condition). Have a door guy adjust it or do it yourself if you know what you are doing.
Then .... plant a shade tree in the middle of your driveway :) just kidding ... how about a shade tree for your neighbor's yard?
My thought as far as insulating the door, if it is metal, is to install the rigid insulation as sugested above and then foam in the edges with minimal expanding foam - the "Doors and windows" kind.
Sorry, I forgot ... depending on your choice of insulation, you may have to cover it ... for fire code reasons. Maybe time to talk w/ the BO. Maybe light gage metal will work. If you use someting else, it may add weight ... which you may have to compromise a little more with in terms of door spring tension. You might want to fill the structure (structural 'tubes' that form the panels) w/ spray foam. There is a fair amount of area in some doors in these structural elements, so their are important.
Install a solar water heating system.
Not sure about the cost of a simple system that will cover most of the roof area, but I can tell you it makes a HECK of a difference!
Out in an area called Redlands, we've got some friends who have an old horse shed behind the house, it's basicly a garage with a flat roof. No insulation anywhere. We got there in the morning on a day schedualled to be over 100, and I thought this shed, which had been converted into a den, would be unbearable hot.
It never heated up, and I couldn't figure out why. It was warm, like the air outside (no AC), but not the punishment grade HOT like it should have been.
Then I realized that the roof was covered with a solar water heating system for the pool water. I had never considered that a solar system could provide double duty by taking away heat before it hit your structure!
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Save the Whales! and Guns!
xxPaulCPxx,Unfortunately my customer wants nothing to do with Solar either H2O or photovoltaics. I'll recheck the temps again next week when everything is installed. Thanks for the input.Pikster
It's great learning from situations like that.
Last summer I was asking similar questions about the intense heat in my garage and attics here in Denver. Over 300 days of sun per year. And a mile closer to the heat source than most of youse.
I got a south facing garage with three doors. The ceiling was already in place and about 3 -4 inches of fiberglass was blown about. But this time of the year the inside of the garage would pass 120. The attics working on 150.
Mike and others suggested the cellulose approach. Best damn advice I've taken yet.
Simple, cheep, and quite effective. It was 97 yesterday. Much less than that in the garage. The attics no longer make the ceilings a heat source. The A/C has no problem keeping up (last year it did) and frequently cycles off (last year it ran nonstop).
Cereally, with the cost of energy increase over the past year, I'm close to having the cost recovered already.