Attic Baffles
#1
02-19-11, 10:09 AM
Attic Baffles
I have an old victorian home that nothing is normal about its construction. I will be insulating the attic soon with cellulose insulation. I have airsealed the attic, but now need to add baffles between each rafter. The problem is every rafter is a different width. Some 8" some 24". There is a material that is used to walk on to protect floors during construction. It comes in rolls and is durable and moisture resistant. I planned on rolling it out cutting where the ceiling joists are and stapling there and the rafters. Is this okay? Otherwise what would be recommended. Currently there is between 1.5" and 3" in the attic. I am putting at least 12" more.
#2
02-19-11, 11:11 AM
There are two areas you need to protect, the air channel from the soffit up above any insulation and the end of each bay to prevent insulation from blowing into the soffits. If you tack in a strip of one inch rigid insulation or wood on each side of each bay, you can then slide in a 1/2" piece of polyisocyanurate (PIC). That's the stuff with a foil face on each side. This way you can cut each piece to fit the different width bays. As for the end of each bay, a dense batt insulation like mineral wool can be cut to length and folded if necessary and pushed in under the PIC. That will keep the cellulose out of the soffits.
Check with local codes to be sure the 1/2" PIC and strips are approved for use.
Bud
Check with local codes to be sure the 1/2" PIC and strips are approved for use.
Bud
#3
02-19-11, 12:48 PM
I can't find mineral wool, so will fiberglass batts work? In the picture the board where the rafters lay is directly above the topplate. By folding the insulation, I can insulate the top plate and stop cellulose from entering the soffits at the same time. Then use the foam panels to go across to keep an air path open and keep out the insulation. Is the picture correct? We don't have codes or inspections around here so thats not a problem. I like the idea of using foam pieces below to block the cellulose, but there are around 80 cavities that I would have to cut each piece for. If I can dodge that I will. Folded insulation sounds better if it will work.
#4
02-19-11, 03:00 PM
Google Roxul. Their locator shows a bunch of locations between San Fran and LA. Fiberglass is what we used to use, but air can pass through it so it becomes less effective just when it needs to be more effective.
This may help posting pictures: http://forum.doityourself.com/electr...your-post.html
To be sure I'm reading you correctly, the folded insulation resolves one problem and the rigid insulation sheets resolves the other, but both are needed.
Bud
This may help posting pictures: http://forum.doityourself.com/electr...your-post.html
To be sure I'm reading you correctly, the folded insulation resolves one problem and the rigid insulation sheets resolves the other, but both are needed.
Bud
#5
02-19-11, 04:43 PM
Its no wonder that the pic didn't take. I used tiny pic. If needed I have cheap plastic clear bags that I can use to enclose the fiberglass batts making it airtight. Here is a pic.
insulation | Flickr - Photo Sharing!
I couldn't get the image to embed, so I just linked it.
insulation | Flickr - Photo Sharing!
I couldn't get the image to embed, so I just linked it.
#6
02-19-11, 05:41 PM
By the time that folded insulation is covered with cellulose, there shouldn't be any air flowing through. It would be a lot more effort, but the foam panel could be recessed with only a one inch gap for air flow to the soffit, but what you show is fine.
I think you have the idea and should be all set.
bud
I think you have the idea and should be all set.
bud
