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williamp2 02-08-2013 09:26 PM

Attic (re)insulation
 
Hi all, I have some questions about attic insulation and I'm open to suggestions.

I have a 1948 1 1/2 story, brick exterior, in central Michigan which faces South. The upstairs is walled off under the roof slope to form two attics on the East and West side. Several years ago I had the windows replaced and all the heat we had been losing through the windows started going out through the attics. We started getting terrible icecycles along all the eavestroughs and ice dams, which lead to water coming into the walls. To combat that I had the old roof removed, a new one put on with rain and ice shield and proper vents, and then I blew 14" of insulation into the attics. That seemed to fix the problem.

Last winter was very mild for Michigan, but we didn't notice any problems. Now that it's cold and snowy again, the icecycles are back, though not as bad as they were before the new roof. When I look in the attics with a flashlight, it looks like all the blown-in insulation by the eaves has shrunk. The rest of the area is just as it was.

I guess my first question is: would it be beneficial to blow in more insulation, and at least try to refill those areas? As you probably know it's quite a mess and rather time consuming. Or is there something better I could do to keep heat from getting up there? Also, on the West side of the house, it seems like the problem is really concentrated around the bathroom vent. The conduit from the ceiling vent to the outside is wrapped in some kind of heavy insulation, but I don't know if that is helping. Would it make sense to replace the ceiling vent in the bathroom? Or is there something I should look into on the exterior?

One other question: Along the front of the house, there is a long room upstairs that is completely walled off on the South side. There's at least a small area where the roof slope continues down behind that wall. The eavestrough above my mailbox always seems to have icecyles on it too. Does it seem like it would be worthwhile to tear out the plaster and see what's going on in there?

Thanks for any insight you can give me!

joecaption 02-08-2013 10:48 PM

#1 Go back and add your location to your profile!
#2 Add some pictures so we can see what your seeing.

gregzoll 02-08-2013 11:39 PM

It does not matter what direction it faces, the house has four corners, it faces North, South, East, West. Now add in the Z axis, you have it facing Up and facing down also.

As for the current attic insulation, if you go up there and take a ruler, in say six or seven spots, and take an average of all the depths, what is the average depth in inches that is up there? Also what does the material look like that is up there (post a picture, since there has been various materials used for insulation in attics, and some are not very good for the health, and can cost money to have removed).

williamp2 02-09-2013 08:03 AM

3 Attachment(s)
Ok, I updated my information and here's a few pictures so hopefully that'll give more information about what I'm asking.

The access door is pretty small so it's hard to get a good measure in a lot of places but based on what I was seeing, it's less than the 14" I originally thought and more like 9 - 10". If you can see from the picture it really drops off at the edge. That's not how I remember it from when we put it in so I wonder if it settled or something.

Not sure how clear it is from the picture, it's the type of insulation that's made from recycled newspaper. I don't remember the brand or anything but we got it at home depot.

gregzoll 02-09-2013 02:37 PM

It appears that you have more than enough up there. As for those scuttles, yep, they are a pain if you are large sized. As for icicles, that can happen from snow melt off the roof, and if they are small no problem, but if you are noticing large patches across the roof, of snow missing, then yes you have issues with heat loss going out into the attic space.

Also, snow melt can cause ice to get up under at the edge, then you end up with rotten wood, and more problems. You may have to go back up and place baffles at the edge of the roof, where it meets the top plate, and roof, so that air can get to that edge, to help keep it at ambient temp of what the unfinished attic space is.

Gary in WA 02-09-2013 10:30 PM

Your overall insulation looks pretty good, as said already. You should have added baffles under the roof sheathing boards, near the eaves, hence the reduced thickness there from wind-washing moving the cellulose away from the exterior wall: http://www.buildingscience.com/docum...d-135-ice-dams The space between roof/wall is so close, no room for standard insulation, should use rigid foamboard there, after you air sealed/canned foam all the wiring/plumbing holes. Seal them in the crawlspace/basement to help stop the "stack effect"; http://www.wag-aic.org/1999/WAG_99_baker.pdf

Foil tape the duct from bath to the outlet hood in the roof, and insulate/vapor barrier plastic the flex ducting against condensation. The fiberglass sidewall insulation should have been covered with a housewrap to prevent air infiltration degrading its R-value.

Gary

williamp2 02-10-2013 09:05 AM

This is great information, guys, thanks!

One more beginner question. Do I just walk out on the rafters to do this work? Will that mess up the insulation that's already there, and if so, do I need to reapply or just redistribute it somehow?

hammerlane 02-10-2013 09:36 AM

Quote:

Originally Posted by williamp2 (Post 1113875)
Do I just walk out on the rafters to do this work? Will that mess up the insulation that's already there, and if so, do I need to reapply or just redistribute it somehow?


Holy cow Batman.....If you could walk out on the rafters then you should be in the circus.

Now if you walk on the joists Im sure the insulation will get scattered. Just redistribute.

williamp2 02-10-2013 12:03 PM

Hahaha! Thanks for the correction, that would have been awkward :)

Canarywood1 02-11-2013 03:59 PM

Quote:

Originally Posted by williamp2 (Post 1114022)
Hahaha! Thanks for the correction, that would have been awkward :)



At 9/10 inches you only have R32,and the reccomendation is R49/60 for your area,here's a calculator for how much more you'll need .



http://final-analysis.com/calculators/insulation.htm

HomeSealed 02-11-2013 04:10 PM

-Get to R50-60
-Air seal all penetrations , especially around the bathroom
-It looks like the kneewalls (side walls) may be under insulated as well. Typically we run batting in each cavity, another layer horizontally across that, followed by covering with housewrap as Gary mentioned.

The air sealing is especially crucial due to the stack-effect that Gary also mentioned.


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