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Bonus Room Air Seal and Added Insulation


blacksport's Avatar
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06-24-12, 08:42 PM   #1  
Bonus Room Air Seal and Added Insulation

I have a 19'6x17'3 bonus room over the garage that is in the sun most of the day.

I'm about to replace the air condition PTHP unit that has been installed since 1991 and was thinking about doing a revamp on some of the insulation as well.

The room has two outside walls, overhead attic space, an outside slanted part of the ceiling then a knee wall with insulation on behind the drywall.

The slanted wall has insulation in it and I believe those attic vents. I have no issues with the floor getting cold / hot.

The knee wall and overhead attic space had R30 already and I was thinking about the following:

Knee wall:
  • R5 Foam Board
  • House Wrap

Attic:
  • House Wrap
  • Layer of R30

I figured these things would be easy to do / relatively cheap / and might help stabilize the new AC unit as the 21yr old one right now has a hard time in the heat of the day.

Is there anything wrong with what i'm thinking of doing?

BTW I'm getting a 9,200BTU GE 6100 series unit.

 
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chandler's Avatar
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06-25-12, 03:41 AM   #2  
You failed to mention the floor. Is there insulation there or do you plan on putting any to keep the cold/heat from migrating from the garage? If you have R30 in the knee wall, the rigid foam will only add a minor amount of insulation. The house wrap will let it breathe.

 
blacksport's Avatar
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06-25-12, 05:37 PM   #3  
The floor under the bonus (in the garage) is insulated and drywall'd - in the knee wall the floor insulated and plywood covers it.

So you are saying just to put House Wrap in the knee wall?

 
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06-25-12, 06:01 PM   #4  
You said it already had r30 in it, so that's about all you'll get in vertical framing. You won't be able to add more without compressing it and that will compromise the insulation value.

 
blacksport's Avatar
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07-02-12, 05:14 AM   #5  
Alright - so this weekend I put R30 Foam board on the back of the knee-wall over the existing r-30 insulation and taped up the seems.

My next job is going to be insulation in the attic above the bonus. Should I put down house wrap over the current insulation and then lay the new insulation perpendicular? Or would laying it perpendicular be just as good?

Lastly - Does anyone know any tricks for running the attic vents along a slanted ceiling that already has insulation in it? I tried just pushing it over top but it looks like I might have to put the current insulation to run these.

 
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