spray foam for a rowhouse renovation
Last Post 02 Jun 2008 07:16 AM by wes. 2 Replies.
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waterfrontUser is Offline
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01 Jun 2008 05:14 PM
Hi all-

I am attempting to get a 1910ish row home to a net zero energy status through an extensive rehab...i'm working through envelope decisions right now and am looking for some feedback.

Specifically, i have questions about foam insulation. 

My upgrade of the envelope strategy includes (amongst many other things):
*open cell direct to the underside of the roof decking
*open cell foam applied to interior non-party walls and band joists, (both for sound and insulation.)  

there will be a handler in the enclosed attic space.  and all bath and kitchen venting will be to the exterior.

I have been getting some flack from folks who are telling me that "since the house was not built for this i shouldn't do it".  Not a whole lot of logic there, but it did make me think...

My main concern is this: if the attic becomes conditioned, water is kept out from a new roof and nothing is vented to the attic the only thing that could be a moisture concern is from the general use of the house going through the ceiling to the attic.  This might be significant in the long run.   Logic tells me that in theory, it will not condense because it's in conditioned space, but i've been in bathrooms where non-venting lead straight to mold.  This gives me pause.

On a related note, the systems are currently:
heating: old fashioned radiator heat
cooling: must install a high velocity system(s) (there are 3 units in the building)
ventilation: TBD...  I am thinking about the ventilation system being the crucial point here...if that space is properly ventilated then truly there is no issue, right?  Or am I wrong in thinking that I will have to ventilate the attic space just because it's conditioned. 

Any thoughts welcome,

Waterfront

ReadyToRetireUser is Offline
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01 Jun 2008 06:52 PM
Waterfront,

Go to buildingscience.com and read up on the importance of air and (water) vapor barriers. 

Larry
wesUser is Offline
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02 Jun 2008 07:16 AM
Waterfront,
I think your ideas are sound. The conditioned attic space makes sense in new or old structures. One key thought, you must allow for air movement in the attic space. This is easily accomplished by adding an HVAC drop and return in this space. This allows the air to move, which keeps the humidity levels in check. You are right, stagnant air is not a good thing, under any conditions.
Wes Shelby<br>Design Systems Group<br>Murray KY<br>[email protected]
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