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Old 02-11-2008, 08:17 PM   #1
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attic insulation/quick ?


I did a bunch of searching but i just wanted to make sure i read everything right. I have an attic that was made into a 3rd floor room by the previous owners. I live in wisconsin. I have four foot walls that tie into the roof joists, then about 3 feet of roof joists with drywall on them, and then a six foot flat ceiling. I am redoing this room and when i looked above the flat ceiling i noticed there is no vents, the insulation touches the roof boards. From what i have read this is bad, i have frost and condensation on those boards now. They are only 2x4 joists. I have a ridge vent at the peak. Should i rip out the insulation on the angled ceiling and put vents in and re insulate? The vents only need to run where the insulation touches the roof boards right? Thanks for clearing this up for me.

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Old 02-11-2008, 10:45 PM   #2
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attic insulation/quick ?


Do you have soffit vents at the bottom of the slope behind the kneewalls? If you put in the baffles for venting they will do no good if there is no soffit vent to bring air up thru the baffle. The condensation you see is from moist air leaking from below. Use sprayfoam and caulk to seal up any and all leaks you find, but be careful with any recessed light cans/sources of heat.
What is the level of insulation in the flat area? It might need beefing up. How are the kneewalls/side attics insulated? Are they blocked off at the baseplate/2nd floor ceiling joists?

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Old 02-12-2008, 08:41 AM   #3
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attic insulation/quick ?


Install baffles/ Rafter vent to get the air circulating from the intake vents (Soffit area) to the exhaust vents (Ridge vents).

As you stated already: remove existing insulation, so as to be able to install the baffles. Make sure that there is direct air access for the soffit vents to work with the baffles to get the air up to the ridge vents.
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Old 02-12-2008, 02:29 PM   #4
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attic insulation/quick ?


Thanks for the help guys. The rafter cavity is 5 1/2" deep, a true 4" rafter and a 2x2 nailed to it to fur it out. Should i take this 2x2 down and install a 2x4" so i can get more insulation in there? Thanks again for your help, especially atlantic for taking the time to share your knowledge and experience with everyone.
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Old 02-12-2008, 03:18 PM   #5
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attic insulation/quick ?


What are you talking about insulating here. The ceiling joist area? Or are you talking about the sloped roof.
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Old 02-12-2008, 03:41 PM   #6
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attic insulation/quick ?


sorry for using joists in the first post jaw. I'm actually talking about the rafters. The joists in between the second floor and attic are 2x10 with blown insulation and then 3/4" ply floor. The knee walls are about three ft tall and insulated, the RAFTERS that will get drywalled screwed to it are 5 ft long from the knee wall to the flat ceiling in the attic which is 6 ft across. The rafters are 5 1/2" thick with r-11 insulation with no baffles, the 6 ft flat ceiling is 2x4 with r-11 itch also, with plenty of room above for more insulation. It has soffit vents and a ridge vent but with no baffles in the rafters and the insulation touching the roof sheating it's forming condensation. The rafters are a 2x4 with a 2x2 nailed to it to get 5 1/2", should i rip the 2x2 off and nail on a 2x4 for more itch after i install baffles or is r-19(i believe for 5 1/2" cavity?) good enough for those 5 ft. Also there is a plastic vapor barrier on the finished side of all this and the insulation is paper faced, this is ok right? Thanks again for your help guys, this house is one project after another but what a learning experience.

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Old 02-12-2008, 09:00 PM   #7
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attic insulation/quick ?


Ok i got the baffles tonight from HD and they are the styrofoam ones, 22" wide. MY rafters are 16" on center and the baffles are perferated in the middle and tear apart to make two 11" baffles. Is this ok since my cavity is 14 1/2" and the baffles are 11". Will i still have condensation problems since the baffles don't fill the cavity or will the 11" baffles be sufficient for venting? Thanks, i can't wait to finish this never ending project!

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