Super-insulated walls retrofit.

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  #1  
Old 10-31-03, 09:30 AM
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Super-insulated walls retrofit.

The plan starts by removing the shoddy vinyl siding (can be done with bare hands) and the original wood siding (bare hands, also) and installing fiberglass insulation in the 3 1/2" stud cavities.

I would also like to add a serious layer of Styrofoam, perhaps 3 1/2 inches worth.

I have no objection to the need to fully sheath the wall in plywood or OSB. Current plan calls for 5/8 plywood (used, on hand)

I am thinking the sheathing goes on first, then the foam, and hang the new vinyl siding on screws that penetrate the foam and attach to the sheathing.


This would be an adequate plan if I didn't have windows to consider. I have windows to consider...


I assume I would need to remove - reinstall the windows to accomodate the increased thickness. I also assume that the challenge is how to create the rough-in for each window, since 3 1/2 inches of foam isn't a solid attachment for windows.

There is also the issue of interior finish trimming.

There is plenty of roof overhang so that's not an issue. Just puzzling over the window details.

I have no objection to you folks proposing alternate methods, or questioning the plan. That's why I posted.

Thanks,
Steve
 
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  #2  
Old 10-31-03, 10:18 AM
Ed Imeduc's Avatar
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Can do

You dont say what the windows are, are what kind. But you could build a box around the windows out of 1" X by the with you need from the outside to the inside for the drywall and siding and then set this new window set up in the wall. If they go right on the wall outside Put wood just around it for as thick as the styrofoam
set the window to it then just use a drywall trim out return on the sides and top of the window and a sill on the bottom ED

Dont forget paper side to the room with the insulation
 
  #3  
Old 10-31-03, 10:42 PM
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Thanks Ed,


Yes, that would be good, thank you.


I am also considering "scabbing" 2 x 4s (on edge) to the perimeter of each window opening, making a 2x4, plywood, 2x4 "sandwich" at each window.

The windows are new construction, though the installer did a good job of breaking off the flanges


The wide variety of deck screws, timber screws, etc. makes this possible. I wouldn't attempt it with only nails.


Steve
 
  #4  
Old 11-09-03, 08:16 PM
jsdavhar
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Hi,

Just a couple of thoughts I had while reading your plan:

Are you planning on using actual Styrofoam or some other foam insulation product? the reason I ask is that I was recently considering insulation options and found that polyisocyanaurate (sp?) has a better R-value than fiberglass per inch. I wonder if the cost of 3 1/2" fiberglass plus 3 1/2" styrofoam might not be more than 3 1/2" of polyiso, which would give you more R-value and perhaps eliminate the need for the additional exterior work?

Just a thought. Of course if you have stuff cheap and/or free that trumps my plan....

john
 
  #5  
Old 11-09-03, 09:02 PM
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Seems that polyiso may not be cost-effective, and it usually has a foil skin. Not so sure that the foil could be inside, and from I have heard, it's not a good idea to have the foil contacting vinyl siding.

Also, polyiso r-ratings may not be stable over time. And, it may not be possible to laminate the foam to achieve the thickness. Yes, the manufacturers offer some pretty thick foams, but the dealers may not stock them.
 
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Old 11-10-03, 01:10 PM
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insulation

Dont know that polyiso if it the same. But an insulation board we use with a high R is a polyurethane .it has a light beer color to it ED
 
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