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Porch Ledger & Exterior Foam Insulation

mrigney | Posted in General Questions on

Ok, question. House is currently being framed. We have Zip and are doing 1″ of exterior foam insulation. On the back of the house, we have a porch that comes off of a gabled end. The framers put up the ledger today directly against the Zip and then framed out the roof for the porch.

Here’s my question. Should they have installed the exterior foam and then mounted the ledger on the outside of the foam? Not sure if that flies structurally, but also know it’s going to be a whole lot harder to cut and fit the foam around the ledger and porch framing now that it’s there.

While I”m asking questions…they also didn’t tape the zip behind the ledger. So I’ve got several seams where 8″ aren’t taped and won’t be able to unless they unframe the porch. What’s my best option here? Should I have them tape the seam between the ledger and Zip?

First lesson of building a home so far has been that to do high performance building…even when you think you have a builder who is amenable to the high performance aspects…you have to constantly be watching to catch stuff. Mentally draining, but hopefully worth it in 6 months when we move in.


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  1. Expert Member


    Yes they should have taped the Zip, and yes they should have run foam behind the ledger. You can either use spacers on the lag-bolts, or something like this:

    However you do it, it's very important to have the flashing details worked out so it integrates with your WRB and siding - which sort of speaks to your concerns about having to police your builder. There shouldn't be any doubts about how details like that get done, because they should appear on the set of construction drawings the builder is working from. If they aren't there, I'm not sure it's fair to complain about them making some assumptions, and doing what they think best.

  2. mrigney | | #2


    Thanks for the quick reply. I think the wall details are pretty well laid out in the plans. Our architect specialized in high performance homes. I'm attaching a picture of the page from our wall detail from the plan to give you an idea of the level of detail.

    Now, with that said, I suppose it is true that there isn't a detail specifically for the porch interface with the house. Guess I assumed that the wall detail would translate well enough to the area where the porch ties in. But maybe I was wrong.

    I think my worry is that somewhere between builder and crew, the details in our drawings that are different from a "typical" build aren't getting communicated well.

    1. Expert Member
      MALCOLM TAYLOR | | #3


      A set of drawings for a house with a deck or porch needs a section through that area. If it isn't included, the builder feels free to fall back on what they usually do - or makes an informed guess.

      There may be other instances on your build where it is true, but I don't see the issue here as a problem in communication between the builder and his crew. Legally and practically, building is set up so that the way things are communicated between all parties are through the construction documents - that is the drawings and specifications. There are some assumptions made about common details, but especially things out of the ordinary need to be called out and described. It's that way to avoid exactly situations like you find yourself in.

      1. mrigney | | #4

        Right, I get what you're saying. And it is true that there isn't a section for the porch ceiling (I suspect partly b/c it was a late add to the plans; just emailed the architect to ask about it). But, with that said, our contract includes plans and an energy spec addendum that calls out things like "R-6 continuous foam insulation on the exterior of the house."

        Part of it might be my expectations of what communication should look like (first time building a house). Between the plans and energy specs that are part of the contract, we (and the architect) have tried to make as many details as explicit as possible. And I get the need for that. Professionally, I'm not a project manager, but work adjacent to and am part of PMs for lots of big aviation systems...totally get the importance of good requirements. I think maybe my expectation was that when there is a potential conflict in requirements ("hey, the way we normally do the porch/deck/ledger conflicts with that energy requirement in the contract to have CI on the whole house") that they would communicate the conflict to me and give me some options for resolutions.

        But again, that might be my expectations mismatched w/reality. Like I said, first time building, so we're feeling it out as we go.

        By the way, I did find this pretty good article from JLC on the topic after a little more googling:

        1. Expert Member
          MALCOLM TAYLOR | | #5


          I'd get y0ur architect to issue a sketch showing how the ledger is to be attached, and how it is flashed both above and below. It needs to make explicit how all the elements of the assembly are integrated together.

          1. mrigney | | #6

            Thought I'd give a quick update. Talked to our architect this morning for a bit. She said w/o getting approval from a structural engineer, she said she would probably recommend attaching the ledger directly to the osb/rim joist. She said you could do something like a Maine Deck Bracket, but might cause more problems than it's worth since the builder isn't familiar with them. She said you'd take a small hit w/the thermal break, but that we could mitigate by spray foaming any gap between the ledger and the surrounding exterior foam.

            Thanks for all the input!

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