Replies

1. 
   rez | Nov 22, 2007 12:18am | #1

   Greetings des,

   This post, in response to your question, will bump the thread through the 'recent discussion' listing again which will increase it's viewing.

   Perhaps it will catch someone's attention that can help you with advice.

   Cheers

    

1. 
   calvin | Nov 22, 2007 12:53am | #2

   I cannot answer your question, tho over the years I've dealt with some commercial situations where space always seems to be at a premium.  Sometimes at the expense of energy efficiency.

   I now might go to the Building Science website and peruse there.

   Since brick is not waterproof, moisture barrier considerations and location should be well thought out.  And the easy answer probably is not just putting up visqueen.

   First I would examine any potential or existing deterioration and possible water entry on the outside.

   Think through the existing conditions of electrical and window and door locations.  Building IN 4 or more inches  will mean extending the jambs or relocating or replacing the doors or windows altogether.  Same with the electric at those outside walls.  Up through the floor or mounted in the basebd might suggest rewiring.

   Best of luck on your project.

   Good of you to think this through before beginning. A great place for Information, Comraderie, and a sucker punch.

   Remodeling Contractor just outside the Glass City.

   http://www.quittintime.com/

    

   Edited 11/21/2007 4:54 pm ET by calvin

2. 
   CapnMac | Nov 22, 2007 01:00am | #3

   Well, I'd be inclined to use 2x3, and leave an air gap between the framing and the brick wall.  Which I'd then fill up with spray foam, as that's most likely to give you the best R value for the least inches of thickness.

   In a perfect world, jsut for the insulation, we'd probably want to jsut build a new insulating plane inside of the existing masonry.  The problem with that ideal is that we also want doors and windows--which "punch through" our building enevelopes and complicate all of this "simple stuff."

   Now, the other way you could do this would be to move the insulation plane to the outside of the brick walls.  There's a lot to recommend this approach.  Like you "gain" thermal mass on the conditioned side of your insulation.  You also then have the framing (the structural use of the brick) seperated from the insulation and weatherproofing of the structure.  Which helps determine where your specific climate "wants" the VB to go--it's still outside the brick, it jsut may be outside the new insulation, too (that's why a general location in your Profile Info can help--hint, hint).

   Best part about going outside is that you have many fewer instances of having to remount electrical and plumbing fixtures in the wall (unlike on an inside wall).

   Occupational hazard of my occupation not being around (sorry Bubba)
1. 
   des | Nov 27, 2007 05:02am | #4

   I thought at first I would keep the question simple, instead i think I need to elaborate. I am a Project Manager for a Habitat for Humanity affiliate in CT. The project is an 1870's brick row house which we are converting into a 12 unit condo. It has been completely gutted so there are no existing mechanical conditions to worry about. It is an historical building so the exterior needs to remain as is. My primary concern is the fact that brick is pourous. Spray foam is costly but I do not want to create a moisture haven in fiberglass bats. Do you think this is a legitimate concern?

1. 
   rez | Nov 29, 2007 06:07pm | #5

   bump 

2. 
   BigBill | Nov 29, 2007 07:19pm | #6

   I do not want to create a moisture haven in fiberglass bats. Do you think this is a legitimate concern?

   Short answer is yes.

   Closed cell foam would be my prefered solution.  Spray or sheet.

    

    

3. 
   Piffin | Nov 29, 2007 10:26pm | #8

   I'll say what would be my concern with this, and no knowledge from exact experience whether it is a valid one or not...I would be predisposed to use a polyurethane spray foam in place like CapMac mentioned.but in your climate, what would happen is that you are now creating a situation where the brick remains a good deal colder during winter than it has in the past, because the building is not radiating as much heat out through it as in the past. And that moisture cannot dry to the interior.There is also less energy driving moisture back out either.In my theory, that means that there will be more moisture in the soft brick and it will be more likely to freeze.The open Q is how much - and how much will it tend to deteriorate the brick as surface flaking happens when the ice crystals drive the surface of the brick off.I prefer the closed cell foams because of the VB they provide, but in your situation, an open celled foam like icynene might be the better choice.You really should try contacting Joe L. at Building Science. This sounds like an interesting situation and he would be sure to comment. Being a HfH he might donate more in the way of consulting... 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

3. 
   mackzully | Nov 29, 2007 08:48pm | #7

   Doing the same down here in DC, in an 1890s rowhouse. What you have to be extremely careful of is the moisture that the brick will absorb and release, especially soft brick. Back in the day, my house had two coal fired stoves in it that were probably going even in the summer, so there were plenty of ACHs continually drying the house. The interior finish on the walls was plaster, so the moisture could move through the wall.

   Unfortunately, once you put a moisture barrier in for modern insulation, you have to think about where all the moisture will condense. The SOP here in DC is to fir out as you're doing, then fg batts, then seal with 6mil plastic. The problem with this, at least in the houses that I've peaked into during the reno, was that the plastic was never sealed correctly around penetrations or to itself, apparently staples are really good at creating an airtight barrier :)

   But that is besides the point, I think this method is not the best for an old structural brick house, as the condensing surface becomes the plastic vb, and hence you'll wet the FG insulation in your walls. I'm sure this insulating technique is fine in a house with proper siding that doesn't absorb moisture like brick, but since the brick *will* get wet and *will* absorb and transport moisture, I want to keep the condensing surface as close to the outside as possible... Therefore, I think that closed cell foam is one of the best options if you cannot or do not want to insulate the exterior. Since it is a vb, unlike open cell, the water cannot escape into the interior of the building. I'm sure there are problems with this wrt the condition of the exterior brick, whether or not it is paint brick, etc. but I would bet it a better solution regardless.

   Z