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Supporting brick veneer over a roof and thermal bridging

whitenack | Posted in Green Building Techniques on

Hi all,

I’ll try my best to describe the situation I’m in as clearly as possible. If I fail, don’t hesitate to ask for more info.

I am building a 2-story brick home with a single story wing on the side. In an attempt to make things economically efficient, I designed the back wall of the wing to be flush with back wall of the main house. The drawback to this plan is that the brick veneer on the wall above the roof of the wing will not have a lot of support underneath it to rest on.

The idea we are coming up with is a steel beam that will sit below the roof and give the veneer the structural support it needs. We plan to run steel posts up from the foundation to this steel beam so we don’t have to rely on the settling of wood over time cracking the brick above it.

There are two locations the steel posts can run: They can run down the outside of the framed wall but behind the brick, using the space that was going to have 3″ of polyiso rigid foam, or they can run down through the inside of the exterior wall, taking up space where blown insulation would be.

Trying to figure out the pros and cons of each location. If it goes on the outside of the wall, I will probably have some thermal bridging since I would not have insulation outside the posts, but if I run the posts inside the wall I will have thermal bridging from the posts to the attic.


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  1. whitenack | | #1

    The final paragraph, second sentence should say, "....would NOT have insulation outside the posts..."

  2. Chaubenee | | #2

    Did an architect design said house for the load of the brick and what was his plan there?

  3. Expert Member

    If the beam and brick above are insulated from the living space, it might make sense to keep the posts outside the insulation too. Otherwise at some point you go from trying to keep the stuff above cold, to trying to keep the posts warm - and they are all connected.

  4. user-4524083 | | #4

    Clay - I don't fully understand the dilemma, and a picture or diagram might help. I'm picturing a 2 story brick home with a pitched roof above it, and on the gable wall a single story "addition" or "bump-out". Why could you not build the main house, and then treat the wing as an addition, bolting the wing roof rafters and the walls next to the house through the brick and foam to the stud wall of the main house. You would then have an interior brick wall in the wing, and the wing would look like an addition. They make stand-offs (used for decks to be built onto wood sided houses with foam sheathing) that you could have ready to receive the rafters that would be waiting inside the brick veneer.And you would have to place counter flashing in the main house brick wall as it went up.( This could be cut into the mortar later as you would for a true addition, but that would be a lot more work.) Unless the wing is very large, this seems simpler than engineering something to hold up bricks with no bricks on the first floor going down to a secure foundation. Basically, what I'm suggesting, is to have that whole wall bricked instead of creating a metal structure to do it. If this is not practical, then Malcolm's idea- to have the metal posts and beam outside the insulation, in the plane of the bricks is a good idea, They could ultimately be hidden behind the interior wall of the wing.By the way, I would recommend NOT having the plane of the wing wall to be in line with the plane of the main house, but rather set it in a foot. I've never seen a wing that sits flush to the main structure that looks right.

  5. GBA Editor
    Martin Holladay | | #5

    As described, it sounds like a massive thermal bridge, as Malcolm noted.

    If I understand you correctly, you want the steel beam to be inside your home's thermal envelope. If that is the plan, you will be connecting a warm-in-winter steel beam with cold-in-winter brick veneer. The brick veneer will be sucking heat out of that beam all winter long.

  6. whitenack | | #6

    Dang Martin, you're up early! Yes, the beam would be up in the attic, in contact with the brick that runs up the wall to outside. So, yes, the beam would be close to the outside temperature. The steel posts that hold this beam up need to run down to the solid foundation. If I run them down the inside of the wall, that's a massive thermal bridge, as you and others have said. The alternative is to run them down the outside of the exterior walls, between the sheething and the brick in the space where the rigid foam was going to be. I guess this is better since I can still have 5-1/2" of blown cellulose between the post and the inside wall. Not as good as the rest of the wall that will have the rigid insulation, but better than having the hot/cold post completely inside the thermal envelope.

    Thanks for all of the replies.

  7. Expert Member

    Why not substitute foam for cellulose in the two stud bays where the posts are to make up the difference?

  8. whitenack | | #8

    Thanks for the reply. The posts will have to be big enough to support the weight, so I don't know how much room inside the stud bay there will be for insulation. Let's say the post is 3", if I position the post directly against the sheathing, that would leave 2-1/2 in a 2x6 stud bay. 2-1/2" of rigid polyiso is R14, which is better, obviously, than a stud bay with no insulation, but is it better than having the post outside the exterior wall which allows you to have 5-1/2" of cellulose between the interior and the post?

    Also, do I have to worry about condensation on the post if it goes inside the exterior wall? In the winter, when that post is really cold, will condensation form on it as I lose warm humid air through the wall? If so, that could cause problems in those stud bays, I assume?

  9. whitenack | | #9

    But that gives mean an idea, Malcolm...

    As stated above, If I set the post outside the exterior wall, I lose the ability to put rigid foam in that space, so I lose some whole wall r value in that space. But, I could fill that bay with rigid foam for a better r-value per square inch. Since we are talking about a single stud bay (x2), we aren't talking about a lot of extra expense vs. cellulose. I know it is not recommended to to put rigid foam on both sides of the wall, since this would not allow the osb to dry, but if that stud bay has foam in the inerior and a 3" section with no exterior rigid foam on the exterior, would that be enough to allow it to dry to the exterior?

  10. whitenack | | #10

    HAHAHA! Malcolm, just re-read your comment #7 and realized that is exactly what you were suggesting! I thought you were suggesting I put the post in the stud bay and cram rigid foam in there too. Geez. I guess I need more coffee this morning!

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