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House wrap and / or rigid foam panels on the exterior?? (under the new siding)


Milemaker13's Avatar
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10-08-10, 03:45 AM   #1  
House wrap and / or rigid foam panels on the exterior?? (under the new siding)

We are going to reside the house. It will need some new ply wood and 2x4s, but what should I wrap the house up in after the repairs? We will put on vinyl siding, and the house is 90 yrs old so the existing sheathing is t&g planks.

Thanks for your input!

 
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Bud9051's Avatar
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10-08-10, 06:09 AM   #2  
Hi Milemaker,
When you are undertaking a project to replace the siding it is a prime opportunity to upgrade your wall insulation, and windows if needed. In older homes, the 4" wall thickness falls short on space for adequate insulation. Expanding the walls to the inside is one option, but another project. That leaves expanding the walls to the outside, a better option, and since you are half way there with new siding, a worthwhile addition to that project.

I called it a better option because when expanded and insulated on the outside the improvements can cover from the foundation to the attic, covering those hard to improve areas at corners, "T" walls, and rim and band joists. The most common approach is adding 2" of rigid foam insulation. John Krigger, co-author of Residential Energy, published an article where he added 4" or more inches to the exterior of his home in Montana. I liked the article and my house needed siding and windows so I'm in the process of adding 3.5" of rigid to the outside of mine.

To answer your question as asked, One of the house wraps will be fine. They allow the house to breathe a bit preventing moisture problems. If you consider thinner layers of insulation, then vapor issues and dew points most be considered.

What is there for current insulation and are the old windows staying?

Bud

 
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10-08-10, 01:08 PM   #3  
There is no insulation in the walls now. Some windows are new, so they may stay, but the others will be replaced or eliminated all together. These few windows are in closets and the bathroom. I don't want windows in either place.

Tell me this, if I add 2-4 inches of rigid foam board, how do I fix my windows and doors?

 
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10-08-10, 02:08 PM   #4  
I decided to move mine to the outside, but some argue they are best left on the inside and trimmed appropriately. But the details are the issue as you picked up and that is the secondary reason I undertook the project. Unfortunately my learning curve is slanted to the outside right now, but the more common approach with 2" is to just add trim. My toughest was the front door as it opened to the inside, yet the storm had to open out. With 3" or more you/we are in new territory.

Here is the article that got me into this project: Home Energy Magazine Online

Basically, there are some details you will have to resolve, but they are wood, insulation, flashing and trim. Those are four items that are important and easy to learn. My business is energy auditing so if I can help with the "benefit" process just yell.

Bud

 
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