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Insulating the unfinished half of my attic (roofline)

Insulating the unfinished half of my attic (roofline)


Old 05-19-09, 09:29 AM
Thread Starter
Join Date: May 2009
Location: Chicago
Posts: 2
Question Insulating the unfinished half of my attic (roofline)

I have several attic insulation questions. Hereís the situation.

The home is a 1919 stucco 4-square in the Chicago area. I canít insulate the attic floor, and half of the attic is finished into an office (with insulation, vents, and finished with drywall) thatís closed off from the other unfinished half. The attic is accessed via a stairwell from the 2nd floor. I am faced with insulating the interior of the roofline. There are 2x4 joists set 16 inches apart, and numerous odd angles due to a dormer with a ďwhole houseĒ fan at the front of the attic.

Goal: I want to make the unfinished attic warmer in the winter and cooler in the summer, and hopefully save money on utilities. Iím doing this work myself out of necessity.

The office at the back of the attic has air conditioning but no heaterÖI heat the space in the winter with 2-3 hours of a small electric space heater when Iím working.

I anticipate buying styrofoam baffles and rolled insulation. I want to confirm a few things:

1. Should I install the baffles under the entire attic ceiling, that is, under each roll of insulation?
2. Will insulating this unfinished space help me achieve my goals? I know the finished space in the attic withstands the weather pretty well, but it also has drywall and two windows (skylight and dormer window).
3. What R-value should I utilize? There isnít a lot of depth in the joists Ė they are 2 x 4s to start, and Iíll be adding the baffles as well.
4. To watch for: should I be concerned about ice dams, moisture, or other risks? So far the finished portion of the attic has been fine, and there havenít been any issues as far as I can tell. The attic office project was done about 5 years ago. What about leaving space / venting the ceiling peak?

Some pix are included via Facebook. Thanks!!

Looking down toward the attic floor

Looking toward the dormer, front of the attic (window at right houses the fan)

Looking up at the peak of the attic ceiling.

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Looking toward the finished office
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Old 05-20-09, 06:50 PM
diyplank's Avatar
Join Date: Feb 2006
Location: Williamsport
Posts: 713
#1 You will need the rafter vent baffles in between every rafter from soffit/bottom to ridge/top. My question though is why insulate unfinished side?? Are you planning on finishing it??

#2 I don't think so!? But I am no pro. Most of your heat is lost through your doors/windows. So make sure those are sealed up well.

#3 You will need to rip some 2x4's in half or 1/3"s and attach them to all your 2x4 rafters. That will give you roughly 4 5/8" to install the baffles and insulation.

#4 yes you need to watch for moisture, ice dams, etc., if you do or even can do this.

Now what kind of vents do you have in the attic that isn't finished?? Do you have soffit and ridge vents?? Gable vents and ridge vents?

If you wanna save money on utilities, make sure the attic floor on the unfinished and even the finished side is sealed and insulated very well.

In the winter you want your attic to be as cold if not colder than the outside. This prevents the snow from melting and creating those ice dams and 10ft icicles that hang from your spouting! They hurt realy bad when they fall on your head.
Old 05-21-09, 06:50 AM
Thread Starter
Join Date: May 2009
Location: Chicago
Posts: 2
I want to insulate in the hopes of making the office space more tolerable. Even with an A/C vent in this part of the attic, it gets hot from the unfinished attic space just outside my door. It's also quite cold in the winter.

Q: Would the insulation keep the attic from getting so hot in the summer? I have to believe it would...

Thus far I haven't had ice dams on the roof near the finished portion of the attic. I believe it's insulated with baffles, and within the finished space it gets no warmer than 68 deg.

Your input is very helpful - thank you DIYPLANK. I'm reconsidering the project in light of your guidance.
Old 05-21-09, 08:25 AM
diyplank's Avatar
Join Date: Feb 2006
Location: Williamsport
Posts: 713
I would wait til more people post to decide. I am just one person. I just have experience w/ this stuff b/c I did a lot of research when I did all my insulating projects.

Is there a way you can see how much insulation you have in your walls of the finished attic?? When you are in the office, do you walk through another door to get to your unfinished part?
Also maybe install an electric fan on your roof. I looked into that, but decided not to do it. That will move more air and keep your unfinished attic cooler in the summer.

I just think it might not be worth the money to buy all that insulation/baffles/staples, etc. to cool your finished office. But I would wait to decide. Usually insulation posts are hot topics. Just post some pics, b/c the one's you did post don't show up on my home computer or the one I am on at work.

Beer 4U2

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