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FortyTwo · 01-27-12, 09:59 PM

This is great info- lets detail this some more! I'm on my 2nd 1.5 story house- and the 2nd floor is the hardest to control the climate in, and besides the efficiency of upgrading the insulation- you reap enormous benefits in the usability of the space with some upgrads.
In my previous house I had 2 sunroofs and the cavities were blown tight with dense pack cellulose. I only had 2x4 roof rafters and had condensation in the winter around the drywall joints in the sunroofs. It was freezing or steaming depending on the season. I was one of the first people who tried one of those asian mini-split heat pumps (see my post on ecomodder) and really enjoyed the extra heat and cool.

My current 1.5 story house is also 2x4 rafters with old mineral wool in the cavity. In the summer you can feel the radiant heat beat thru the south ceiling.
So far- I added significant cellulose blown into the the area behind the knee walls- added plastic shutes down to the eaves for ventilation and even added 4 ft of foil on the roof rafters to reflect out the summer heat. The main problem is the cathedral ceiling that only has a 2x4s depth of poor insulation in it. During the last cold spell I used a laser thermometer, and the cathedral ceiling was a good 8-10 degrees colder that the rest of the walls.
I guess I'll have to rip out the drywall and add foam. If its on the inside do I even need mooney wall 2x2's, or can I just put 4x8 sheets across the the rafters after filling the rafter chase and drywall over the top of the foam?
Also- I'm still not sure how to vent these things so they don't get moisture problems. The bottom roof- behind the knee walls- has many roof vents all around. The top of the roof has a small area above my ceiling that is also vented pretty well. I may get a new roof thanks to hail and tornado damage if my insurance company doesn't fight me too much- so I'll probably get a ridge vent. My only concern is that I either plug the cathedral part totally and rely on the lower and upper areas to vent separately, or I jury-rig some venting kit inside the 2x4 rafter and still insulate it with whatever small area is left. Seems like a poor solution either way. And no- I've asked every roofer around if they would add a couple inches of foam and they won't do it if the area below the roof is vented. That means major detailing around the eaves and everywhere if foam is added on top of the roof- which means I might as well remodel and add a whole new 2nd story.
I'm more curious about the ac-hacker method. seems like the only way you can get it done without permits and moisture problems.....

01-27-12, 09:59 PM	#4
FortyTwo The answer is renovation Join Date: Dec 2009 Posts: 3 Thanks: 25 Thanked 0 Times in 0 Posts	This is great info- lets detail this some more! I'm on my 2nd 1.5 story house- and the 2nd floor is the hardest to control the climate in, and besides the efficiency of upgrading the insulation- you reap enormous benefits in the usability of the space with some upgrads. In my previous house I had 2 sunroofs and the cavities were blown tight with dense pack cellulose. I only had 2x4 roof rafters and had condensation in the winter around the drywall joints in the sunroofs. It was freezing or steaming depending on the season. I was one of the first people who tried one of those asian mini-split heat pumps (see my post on ecomodder) and really enjoyed the extra heat and cool. My current 1.5 story house is also 2x4 rafters with old mineral wool in the cavity. In the summer you can feel the radiant heat beat thru the south ceiling. So far- I added significant cellulose blown into the the area behind the knee walls- added plastic shutes down to the eaves for ventilation and even added 4 ft of foil on the roof rafters to reflect out the summer heat. The main problem is the cathedral ceiling that only has a 2x4s depth of poor insulation in it. During the last cold spell I used a laser thermometer, and the cathedral ceiling was a good 8-10 degrees colder that the rest of the walls. I guess I'll have to rip out the drywall and add foam. If its on the inside do I even need mooney wall 2x2's, or can I just put 4x8 sheets across the the rafters after filling the rafter chase and drywall over the top of the foam? Also- I'm still not sure how to vent these things so they don't get moisture problems. The bottom roof- behind the knee walls- has many roof vents all around. The top of the roof has a small area above my ceiling that is also vented pretty well. I may get a new roof thanks to hail and tornado damage if my insurance company doesn't fight me too much- so I'll probably get a ridge vent. My only concern is that I either plug the cathedral part totally and rely on the lower and upper areas to vent separately, or I jury-rig some venting kit inside the 2x4 rafter and still insulate it with whatever small area is left. Seems like a poor solution either way. And no- I've asked every roofer around if they would add a couple inches of foam and they won't do it if the area below the roof is vented. That means major detailing around the eaves and everywhere if foam is added on top of the roof- which means I might as well remodel and add a whole new 2nd story. I'm more curious about the ac-hacker method. seems like the only way you can get it done without permits and moisture problems.....