Insulate soffits?

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  #1  
Old 10-25-08, 07:11 PM
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Insulate soffits?

I own a condo on the second floor of a 2 story building. II have access to the attic above me in which I am in the process of adding more insulation.

The building was built in the 50's and the insulation in there is about 3.5" thick with a paper-like vapor barrier on the bottom. My plan was to add another 3.5" thick layer of insulation to the top of that to meet the top of the 2X8 joist and then add one more layer in the opposite direction on toop of the joists.

The kitchen has soffits above the cabinets. In the attic the insulation was pulled right over the soffits leaving them completely hollow.

So... Should I fill those soffits with insulation, or leave them hollow and just go over the top?
 
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  #2  
Old 10-28-08, 09:32 AM
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Location: St. George UT
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You do not need to insulate the soffit. And if they are vented, make sure you dont block the air flow.

You will probably find it less to have a contractor blow the insulation in your attic. They will probably do it, (material and labor), for less than what you can buy the fiberglass batts of the same R-Value.

Blown insulation (I recomend cellulose) is 25-40% more effective than fiberglass batts of the same R-Value (installed)

Get a couple of estimates for blowing the attic, if you know the sq. footage they can probably give you a quote over the phone. If you only have a 3.5 inch batt now (R-11 or R-13) you should consider an R-30 or even R-38 additional. (dependant on where you live)
I would recomend Cellulose and I would also insist on the proper amount of bags installed! (Be there and count them as they do the job) I can figure the bag count if you would like. Just give me {morrisonlarry-at-msn-dot-com} the name (Manufactuer and type) and size of bags they will be using....they are required to do this by law.
 
  #3  
Old 10-28-08, 11:29 AM
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I disagree. You do need to insulate and/or seal these particular soffits. If the kitchen soffits over the cabinets are actually open to the attic space what is happening is that cold attic air is circulating right down to the kitchen and helping to transfer heat up and out to the attic.This is occurring right now despite the fact that fiberglass is pulled over them since fiberglass batts do nothing to stop the flow of cold air. what i would do is either seal up the tops of the soffits with pink foamboard cut to cover the tops and seal with sprayfoam, or just fill it with the cellulose when you blow the attic space. If theres no top plate there over the soffits be sure to check all the other interior walls as well as any gable walls to see if those are open to the attic space as well. If not then seal those too in the same way before you blow.
 
  #4  
Old 10-30-08, 08:41 AM
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You are correct about the soffits over the "kitchen"...

I had it in my mind that the soffits in question were the outside soffits or overhang. thanks for caching my mistake!
 
  #5  
Old 11-01-08, 12:09 PM
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Thanks for the replies guys!

You are right about the walls being open into the soffits. There is a top plate, but it is at the top fastened to the joists. When I look down into the soffit I can see right down the wall as well.

To seal the tops of the walls, is it necessary to go as far as installing foam board and sprayfoaming it? I know I'm going to sound lazy for this, but I AM! It seems like a lot of work and frustration, I can see myself trying to hold the foamboard at the top of the wall as I spray around it and the board falling down the wall and me cursing and yelling! What if I used plastic? Maybe jammed some fiberglass insulation in there with some plastic sheeting (the insulatiion to hold the plastic tight against the side surfaces). That would stop a lot of the aifflow, correct? Then I could just fill over the top of that with blown in insulation when I fill up the soffits. Does that sound ok, or will it be a waste of time?

One other issue I found today. My condo unit is a simple square, the North and South walls are outside walls with windows, the East and West walls are separating me from my neighbors on each side. These walls are firewalls, cinderblock that goes from the basement all the way up to the roof in the attic. When I checked out these walls today I noticed that they are not framed with typical 2X4's. The walls are framed with 1X3" strips shot onto the cinderblock wall every 16 inches, then the sheetrock (well, rocklathe actually) is nailed directly to that.

So that leaves me with a gap about 7/8" that air can flow directly from the attic down the wall. This gap is too small to blow insulation into, would it be ok to just stuff some fiberglass into the top real tight just to try and stop all the airflow?

Thanks for the help!
 
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