Garage walls insulation


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Old 10-20-14, 12:31 AM
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Question Garage walls insulation

I live in AZ and I've turned a one car garage into a work space, during the summer months it can get to blistering temps so I'm working on a plan as it cools off to insulate the walls and attic before the summer heat boils in again.

One north wall is shared with our house so that has insulation, the garage to the east I already put foil insulation backed by 1/2" foam and it helped a ton.

The attic I'm going to put foil across the rafters then roll insulation on the floor, that one is pretty easy.

The South wall has 3 windows that I plan on also putting foil into(wife will probably request I paint it black) and then backing with foam and my question then comes down to how to insulate the two hollow (South and West facing) walls?

Drill holes and blow in insulation or rip out the sheet rock, put bats in then put the drywall back?

With just a computer and maybe a small space heater and I'm good for the winter, I have a 15k portable AC I put a vent into the wall for and it just cannot bring the temps down during the day with two sun baked walls and the attic with zero insulation, so I need to do something.

Not sure which is the cheaper or better option to go with? Being in AZ is adding foil to a wall worth the expense?

Really appreciate any responses.
 
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Old 10-20-14, 05:00 AM
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Hi bb and welcome to the forum.

You didn't mention attic ventilation in the garage area, soffit, ridge, gable, or roof vents?

If you can DIY the blown-in insulation or hire a contractor that would be fine. Attic floor could be included in that process.

The foil in the attic will trap some of the heat above the foil which will then vent out and radiate from the hotter roof exterior. In a wall cavity, if the heat is blocked on the interior, it is less effective as there is no way to vent it away.

As for the windows you need to be careful. Foil on the inside could trap excess heat and damage the windows. On the outside it blocks the heat before the windows have to deal with it. White on the outside with a foil surface facing the window would be better than black .

Bud
 
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Old 10-20-14, 11:13 AM
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Thanks for the response Bud,

The house was built in 2002 so it has the vents to code then for a flat tile roof o'hagen vent, along with the bird holes and gable vent at the end. my house is a U shape and this garage is perpandicular facing to the house and with the gable vent above it facing the street.Name:  Untitled-1.jpg
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I wouldn't have any problem blowing in insulation myself, even drilling a high middle and low holes to make sure all the points are hit then put vent covers on the top holes to come back in a few months and stuff more insulation in when it settles. I didn't say it but I planned on adding attic baffles as well because I planned on packing the attic above this area, giving it the highest R-rating I can.
 
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Old 10-21-14, 04:06 PM
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I had a business come out and give me a quote for blowing insulation in and for two external walls and blowing in the attic they said $646. That would be filling the walls no drywall repair though and filling the attic to R38.

I'll call for a second or third quote, seems a bit high for two walls and a attic in a 20x10 area?
 
 

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