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Balloon framing and stone walls

FrankFulton | Posted in General Questions on

We just learned that some of the walls in our 1950s Cape are ballon framed (sort of). I’ve read GBA and Googled, and I haven’t seen anything that mirrors our exact construction. An open gap runs behind the plaster from the crawl space to the top of the first floor, where 2×4 horizontal blocks are present. At the first floor eaves, these blocks rest 18″ from the top of the studs (there is no top plate). On the gable ends, the studs appear to continue to the top attic, where the same setup appears (2×4 horizontal blocks 18″ from the top of the studs, no top plates). So there is not technically an open cavity from crawl to attic, but the studs do seem to run top to bottom at the the gable ends.

The insulators rigid foamed and sealed all of the basement rim joists, but did not block the bottom of the vertical bay behind the rim joist (as we didn’t know these were balloon framed). Similarly, the tops of the 2×4 blocks at the eaves and in the attic were sealed, although not nearly as well as the basement. No action was taken at the first/second floor transition, where the top of the stone wall meets the bottom of the siding. From the photos I took with my boroscope, it appears our first floor walls are R3: stone>furring strips>plaster. The second story walls appear to be insulated with 3-4″ of rockwool.

1. Given the well-sealed rim joist areas and somewhat sealed tops of 2×4 blocks, is it worth undoing/redoing the air sealing at top and bottom of the balloon frame vertical bays? This would be somewhat labor intensive (eg, redo the rim joist areas) but we’re willing to consider.
2. What kind of air sealing results might we expect with grain bag approach in bays at top of first floor/stone wall transition at gable ends (ie, insulating from inside)?

All experience-based suggestions welcome.

Otherwise, our plan is to move to the internal air barrier and air seal the heck out of the baseboards, outlets, and so forth. In terms of insulation, rather than risk moisture problems in walls (or tear our house apart to spray foam the stone), we are creating a few double-thermal barriers to increase comfort, eg placing batts at floor in newly encapsulated crawl space.


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  1. user-2310254 | | #1


    I am replying to your post to give it a bump.

  2. Expert Member
    Michael Maines | | #2

    I propose making GBA a verb, like Google: "I GBA'd the answer...."

    Emerson, is there any chance you could post drawings or photographs of your situation? I've read your description several times and have seen many different ways of building, but don't quite follow yours.

  3. Expert Member
    Dana Dorsett | | #3

    Can you post some of the boroscope pictures?

    I'm not clear on the wall's stack up. As describe it is a stone veneer siding mounted on some furring (presumably the furring is fastened to the studs), with NO #15 felt or other weather resistant barrier, and NO wood sheathing, with a plaster & lath interior?

  4. FrankFulton | | #4

    Thank you, Steve.

    Michael, I use "GBA'ed" all the time. We've only been in this house 3 months, and my wife tells me she has heard this too much! I'd value your input on framing. Photos to follow - if you tell me what else would be helpful I'll track it down, eg, I'm not certain the studs extend all the way up at the able ends.

    Dana, photos pending. Thank you. I tried to email you a while back, btw.

  5. FrankFulton | | #5


    These 3 photos were taken in at the gable end of a newly conditioned kneewall space, front side of the house:

    1. Gable end - note the studs are parallel, not perpendicular, to the end of the house. The studs are coming from below. The floor joists appear nailed to the studs (?). There are horizontal boards and other blocks in the vertical bays, however.
    2. Approaching cavity
    3. Close up. The stone on the left is the top of the stone wall, which ends at the 1st-2nd floor transition (stone wall meets siding). Note this photo probably captures the best sealed area, in terms of these vertical bays, in the house. The eaves were much more difficult to access, and the insulators knew I would be checking! To the very left (ie, behind the large amount of foam), the space is just as leaky as the area in the photos, used used to be.

    If this is balloon framed, the horizontal blocks and boards certainly block some air, but it's also functionally very leaky. The insulators told me they sealed the similar "missing top plates" at gable ends in the attic, but I was only able to check in a cursory fashion prior to cellulose being blown in. At some point when Im up there anyway, I can QA/redo those if needed. The "missing top plates" at the eaves were less well sealed, I am sure. But we used rigid foam to move the thermal boundary to the roofline, and inside the kneewall the eaves are reasonably airtight.

    What additional photos would help you, help me?

    Thanks so much.

  6. FrankFulton | | #6

    Michael Maines

    Dana Dorsett

    One more pertinent photo, taken before the insulation upgrade. This is at the eaves in the kneewall. The setup is very similar, but might have a second vertical cavity that the above gable end ares does not. From far to near:
    1. Soffit, typically unvented
    2. Far cavity is related to the stone wall (you can feel the mortar).
    3. Near cavity mirrors the cavity described above (ie, apparent 1-story "balloon framing" with no top plates and horizontal blocks).

    Based on a thread I read here, I instructed the insulators to seal the near cavity but leave the far cavity open to allow the stone to air dry. I was unable to QA this work, so I'm not sure how well this was sealed (suspect poorly).

    Again, main questions are 1) should I redo any of the work or leave well enough alone, and 2) assuming that the 1>2 floor transition is where much of the leakage in the house occurs, what other steps should I take, if any, to air seal?

    Thank you.

  7. Expert Member
    Michael Maines | | #7

    Emerson, that is an interesting assembly. I've seen a lot of different ways to build a house but this is a new one for me. It's hard to advise you without being able to see things in person, but my best guess is that the safest thing to do is leave the gap a bit open at the top so the walls can dry.

    I don't think you mentioned your climate zone, but if you live in a place where it rains or where you heat the interior--if you're insulating and air-sealing you probably do--closing up this assembly could create moisture-related problems. I would air-seal the interior as best you can, but leave the exterior to dry.

    If you want additional R-value, you could add rigid insulation toward the interior. Or wrap the exterior with continuous insulation and new cladding, but that's probably not going to happen....

  8. FrankFulton | | #8

    Dana Dorsett,
    Our bedroom is in a 1-story bumpout and framed the same as the rest of the first floor - recall we are in a cape. Photos:
    1. The corner from inside the room. I pulled back the loose, leaky quarter round and found a nearly 1/4" gap between the floors and bottom of drywall. I worked the boroscope camera into that space. Once we diagnose and plan, we will remove all the quarter round, caulk or foam that entire gap, then re-install the quarter round, unless we are advised otherwise.
    2. Looking straight ahead.
    3. Looking directly leftward. The gap runs down behind the "rim joists" in the newly encapsulated crawlspace below.

    I have found several credible reads online suggesting that the air gap behind the stone is why we have no moisture problems (that I am aware of).

    Please let me know what other photos would help you, help me. Thanks for sharing your expertise.

  9. FrankFulton | | #9

    Michael Maines,
    I appreciate your taking a look. We are in CZ4. Your suggestion is exactly how I instructed the crew - seal the "top plate" of the neat bay, but leave the far bay open to breathe. I suspect even the near bay was not fully sealed, and based on your suggestion, oh well.

    1. To you, is this balloon framing? FWIW, the house does seem very solidly constructed.
    2. Would you take any action to seal the gamble ends, where the first and second floor connect?

    Otherwise, our plan is to upgrade windows and create a few double thermal boundaries in cold areas (eg, insulate floors above encapsulated crawl space), rather that adding new interior insulation/drywall.

  10. Expert Member
    Michael Maines | | #10

    Emerson, I'm sorry but I really don't know how to classify this construction system. In fact I'm still not 100% clear on how it's constructed. It seems like it could have been a structural stone veneer, which was then strapped and framed on the interior. Or they framed a minimal structure and then built a stone veneer, but without any of the usual layers in between. Without fully understanding the system I can't advise you on what is safe to seal and what is not.

  11. FrankFulton | | #11

    Michael Maines,
    Thank you. I did just learn that the stone walls are "double" - cinder block on inside, and some seemingly substantial (but I am a novice) stone veneer on the outside. The house was either built by, or at least owned by, a mason. How this impacts the two bays, I am not sure. FWIW.

  12. FrankFulton | | #12

    Michael Maines,
    One more photo, if this sheds any light. This is a floor joist bay, taken from below in the basement crawl space. You can see the cinder block wall, which sits behind the stone exterior, as well as a duct running L>R. You can also see what looks like a bottom plate for the 1-story wall, above, which is notched into the floor joist. I am blocking this "rim joist" with rigid foam.
    Thank you. Happy holiday weekend.

  13. FrankFulton | | #13

    Dana Dorsett, Have you ever seen a setup like this?

  14. CMObuilds | | #14

    It seems like the stone was laid up first, then the house was built inside.

    In #12 using a cut-in ribbon because the stone was up first and it would have been impossible to install a rim board and nail it into the ends of the floor joists. Or the picture happens to be at a doorway, they used to notch thresholds into floor framing.

    #5 picture 3 took a second to realize the picture is sideways. It sure looks like the 2x between the stone and plaster is mounted to the stone and some sort of horizontal member at the bottom of the plaster, looks like all of that framing is hanging off the stone.

    Is your foundation two block thick? So the stone sits on block and the floor framing is sitting on block as well? From the outside under stone at grade is it block?

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