MyFloridaCode.com

So what I'm hearing from you guys is that we don't even have to use the
faced batt insulation?  Obviously, the advantage of using the faced is the
ability to use it to hold the insulation in place.

 

From: codetalk-bounces at myfloridacode.com
[mailto:codetalk-bounces at myfloridacode.com] On Behalf Of Mark Cramer
Sent: Saturday, February 06, 2010 2:40 PM
To: codetalk at myfloridacode.com
Subject: [Florida Code Talk] Vapor Barrier

 

What Dr. Joe said.

 

You don't need a vapor barrier in cooling climates. You really don't want
one. If you did install one, you would want it on the exterior (warm) side
of the insulation.

 

In our climate, water vapor will move in both directions (to the interior
and to the exterior) at different times of the year. The difference in vapor
pressure and temperature is not as great in our climate as it is in extreme
heating climates, so we typically don't have the same issue with
condensation as you would get in a very cold climate. Better to let the
vapor move through the wall in whatever direction it wants, and make sure
the wall can dry out. 

 

The biggest mistake I see contractors make in our market is the use of foil
faced foam insulation boards on the interior of concrete block walls. This
causes vapor moving from the wetter exterior to the drier interior to
condense on the exterior side of the foam board (inside the wall assembly)
where it creates conditions conducive to mold growth. Better to use an
unfaced board with a high perm rating and let the vapor dry to the interior.


 

In Northern climates where they do need a vapor barrier and are using spray
foam insulation, I've heard that they spray a layer of closed cell foam to
provide the vapor retarder/barrier then spray open cell foam.

 

Mark Cramer

Mark Cramer Inspection Services, Inc.

492 20th Ave. 

Indian Rocks Beach, FL 33785

727-595-4211

http://www.BestTampaInspector.com

 

From: codetalk-bounces at myfloridacode.com
[mailto:codetalk-bounces at myfloridacode.com] On Behalf Of Ken Rodgers
Sent: Saturday, February 06, 2010 2:01 PM
To: codetalk at myfloridacode.com
Subject: [Florida Code Talk] Vapor Barrier

 

Can someone give me the code reference for interior vapor barrier
requirements over insulation.  I'm specifically trying to find the
requirement (if any) for a vapor barrier over open cell foam.  The research
I've done seems to indicate the need for a vapor barrier over open cell but
there seem to be a few other opinions out there as well with regards to our
part of the country.  Just wondering if the code addresses this specific
situation.  I'm sure this question will also spark a good foam vs. anti-foam
debate so I look forward to learning from that as well.

 

Thanks

 

Ken

 

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