Replies

1. 
   xxPaulCPxx | Jun 07, 2012 12:39am | #1

   Could you explain that existing roof a little better?

2. 
   cirino | Jun 07, 2012 06:25pm | #2

   Thanks for caring. The area to be insulated is an addition. The ceiling joists are also the rafters witch are pitched at 1/2" per 12".

   It was built this way to support a deck built on parrapets directly above that will accomidate a 2nd floor door 3" above the finished deck.. The walls are 2 x 6 and will have R-19 faced fiberglass insulation. The floor was built with 2 x 8's with a crawl space under it. The space is open to the basement on one side and not vented anywhere else. The floor will also have an R-30 insulation with a vapor barrier placed on the underside of the floor sheathing. BTW the area is about 9' x 14' with 8' walls. I hope this helps. Thanks

1. 
   xxPaulCPxx | Jun 09, 2012 08:58am | #3

   I think you are right to question the double vapor barrier.  The only thing I would worry about is the moisture from the basement.  How wet it is down there?

2. 
   seeyou | Jun 13, 2012 06:55pm | #4

   Any place that sells epdm will also sell "one way" vents to exhaust moisture that could potentially build up in this situation.

3. 
   Scott | Jun 18, 2012 10:36pm | #5

   I think you need a vapor barrier.

   Think about showers, boiling pots, and other sources of water vapor in the conditioned space. That humidity will migrate from the warm interior air into the cooler space beyond the insulation. At some point, the "dew point", it's going to condense and start to drip. During cool months the dew point is bound to be somewhere between the living space and the rubber membrane. Big problems down the road.

   Better to install a normal vapor barrier right near the conditioned space to prevent future rot problems.

1. 
   [email protected] | Jun 19, 2012 07:50pm | #6

   Absolutley no barrier.

   The water vapor must have an escape path.  If you put a vapor barrier there is no where the water that gets in there can escape, and the wood will be susceptible to rot. 

1. 
   DanH | Jun 19, 2012 08:59pm | #7

   How does the water get in??

1. 
   [email protected] | Jun 20, 2012 11:09am | #8

   It just does

   Water gets into almost everywhere.  It is nearly impossible to seal it out entirely. 

   It is a lot easier to successfully design and construct escape routes, than it is to design something that is truly water proof.