Enclosing a deck, insulation questions

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  #1  
Old 10-24-05, 04:44 PM
ncdiy
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Enclosing a deck, insulation questions

I currently have a 10' x 20' deck, parallel to the back of my house. It is covered with a shingled roof. The bottom of the floor joists are about 5 inches off of the ground. I am enclosing the deck to make a "sunroom." I am framing the walls and putting large double paned windows and insulated doors as if this was going to be heated square feet. Due to the fact that there is a patio slab beneath the deck on one end, (about 5 feet), the existing footings are not adequate per code to have this room classified as heated square footage. So, I need help regarding the flooring.

There is no vapor barrier on the ground beneath the deck. I was going to just put felt paper on top of the existing deck boards, then ext. grade plywood on top of the felt paper, then pad, then carpet. I was told that moisture would rise to the felt paper then the deck boards under the felt paper would stay moist leading to mold/mildew/rot down the road.

If I remove all of the deck boards, put down heavy mil plastic on top of the joists, letting it sag between the joists, filling those sags with some type of insulation, replacing the deck boards, then felt paper, then the 1/4" plywood, then pad, then carpet, will I be free of worry regarding the moisture issue. I will be installing the 3" round vent louvre plugs around the exterior band of the deck at the space between where each joists attaches to the exterior beam of the deck.

I would also like to know if this is the proper order in which to wrap/insulate the wall between and below the 4' x 4' windows. From outside inward: vinyl siding/felt paper (taped at the seams)/OSB sheathing, insulation between the studs/whatever wall covering I decide on, (paneling, etc.)

I know, I know....long winded! It just seems that most posts leave out so many details that it makes it hard to answer porperly. Thanks for any help!
 
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  #2  
Old 10-24-05, 07:45 PM
Join Date: Mar 2005
Location: USA
Posts: 6,126
Enclosing a deck, insulation questions

The 5" between the joist and the ground is far less than desireable. If you can lower the ground. Even if you do, put a vapor barrier over the ground to minimize the moisture avalable to be absorbed by the deck. Even if there is some circulation, you can have condensation if the wind is not blowing. This is very impoertant if you do decide to heat it in the future. - Most people do end up heating the conversions sooner or later.

Dick
 
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Old 10-24-05, 08:12 PM
ncdiy
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Thanks Dick. Lowering the ground under this expanse of deck with all joists in place is not going to happen. With a lot of effort I can probably work in poly under the joists. Must all seams be sealed for poly on ground? Does the scenario in my original post not work?
 
  #4  
Old 10-24-05, 08:23 PM
Join Date: Mar 2005
Location: USA
Posts: 6,126
Enclosing a deck, insulation questions

The seams should be sealed, but it is not absolutely necessary since it is outside. Just do your best. You can hold it in place with some landscape rock. If you remove the the deck boards it will be easy to do right.

Others are better versed in the insulation/vapor barrier for the walls.

Dick
 
  #5  
Old 10-25-05, 05:09 AM
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Originally Posted by ncdiy
I would also like to know if this is the proper order in which to wrap/insulate the wall between and below the 4' x 4' windows. From outside inward: vinyl siding/felt paper (taped at the seams)/OSB sheathing, insulation between the studs/whatever wall covering I decide on, (paneling, etc.)
You didn't specify a vapour barrier between your interior wall covering and the insulation.
 
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Old 10-25-05, 08:17 AM
ncdiy
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I assumed that the paper backing on the insulation would act as the vapor barrier.
 
  #7  
Old 10-26-05, 05:13 AM
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Sorry, your message did not mention the use of paper back insulation.
 
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