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Community and Q&A

Partition walls AFTER outer walls?

John Klingel | Posted in Interior Design on

Looking at a picture of the ADA recently, it occurred to me that installing partition walls after the exterior walls are sheet rocked would eliminate a few lines of goo, and another source of air leakage. What would be the problem w/ doing that? Build the partition wall, stand it up, shim over the top plate, and sheet rock it. No? Thanks. j

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  1. Doug McEvers | | #1

    John, You may want to provide some backing but your idea is a good one, carry this theme for the ceiling as well.

  2. GBA Editor
    Martin Holladay | | #2

    Nope, it won't work. Your plan makes rough wiring impossible. Romex has to go from partition walls to exterior walls all the time, for light switches and continuing circuits. So the electrician will insist on the partition walls being in place before he or she shows up -- and before any drywall is hung.

  3. Lucas Durand - 7A | | #3

    John, this idea came up before in this thread:

    ADA is not used in the detail discussed in that thread, but since you are from a climate even colder than the one I live in, you may be interested anyway.

  4. John Klingel | | #4

    Martin: Wiring will be impossible? Just stick the 12/2 out of the exterior wall, goo it, build your partition wall w/ a pre-drilled hole, and slide the wall over the wire. Simple. The electrician and sheet rocker are speaking, so I will be able to take care of any whining! I was just wondering if I missed anything, as it seems like such a simple thing to do. Thanks. j

  5. Riversong | | #5


    If you're doing all the wiring and rocking, then you certainly can do it this way, but I don't think it saves any time or effort since it's really so simple to goo the partition take-off as it's assembled. Even when I do the wiring, I prefer to pull all the rough-in at once.

    Where it does pay, however, to rock before partitions is at the upstairs ceiling, since ceiling air barrier continuity is so much more critical. It's also a lot easier to hang the ceiling as one unit rather than cut and piece the ceiling together. This gets even more simplified if there are no ceiling-mounted electrical fixtures, so that all wiring can be in the walls (with perhaps one run to the attic for a couple of pull-chain lamp-holders and a possible radon vent fan).

    I actually prefer a bedroom floor to be indirectly lit with wall sconces and switched receptacles for table lamps. It makes for a more intimate space, and it also allows the ceiling to be lowered 6" which saves materials, reduces heated volume, and allows the ceiling to be taped and finished from the floor (at least if you're 6' tall, as I am).

  6. John Klingel | | #6

    RR: ok. will insert into the equation. the lid is a definite; i could use some more "intimacy motivators" in the bedroom, too. oh; i see you rated in the pluses this time; movin' on up! j

  7. Nathan Spriegel | | #7

    Actually this is shown in one of Mr. Lstiburek's books (Builder's Guide to Mixed Climates, page 257). With proper planning it should not be any more difficult than the usual method. Combined with drywalling the entire ceiling prior to partition wall installation, as previously discussed on this forum, it also can reduce drywall cutting/fitting. I imagine it also works well with the "advanced framing" 2' modules and not having to deal with "extra" exterior wall studs.

  8. Steve El | | #8

    Seems like this approach with some other tweaks would let you preplan for the easiest possible reconfiguration of the space, should the family's space needs change.

  9. John Klingel | | #9

    Steve: That is a good point. I am just doing a bathroom reno, and was pleased to find that I had (accidentally, I am sure) left a large loop in a 12-2 wire. That made adding a receptacle a bit easier. Perhaps intentionally leaving extra wire in interior walls would be a good idea. I already install way more receptacles than recommended, so moving an interior wall over one to get juice would be pretty easy. j

  10. Garth Sproule 7B | | #10

    Here is another thread where this topic was discussed. I am a believer in the technique, but agree it will only work for an owner/builder.

  11. John Klingel | | #11

    Garth: Good read. Thanks. That is to what Martin was referring when he said it would not work; he is used to specialized crews, and for them it would be a PITA. For me, it'll work. It was interesting reading about the outside showers, too: I have 12" hose bibs so I don't have freeze/disconnect issues. later. klingel

  12. Riversong | | #12

    Speaking of outside shower, here's an interesting item I found that I just had installed on my lake-front cottage project: Woodford 22SF

    It's an outdoor, frost-proof, mixing faucet that can be set up as an outdoor shower. Click on "shower installation".

  13. John Klingel | | #13

    I just thought of a potential problem w/ sheet rocking the lid first. If one is installing the sheet rock so that it "floats" at interior walls (to allow for truss movement and not crack joints), this would eliminate floating the sheet rock. I am not real familiar w/ floating sheet rock, but an engineer explained about the clips, etc, and advised it on a house we were going to build; 44' span, load bearing interior wall at 22'.

  14. Riversong | | #14

    Yup, truss uplift would be a problem. It tends to occur with trusses >26' span, 8" of insulation on the attic floor (covering the bottom chord).

    That's one of many reasons that I avoid roof trusses, but that's a crazy span.

  15. John Klingel | | #15

    What impact does the ">8 inches of insulation" have? j

  16. Riversong | | #16

    What causes the uplift is differential moisture content between the warm, insulated bottom chord (dry and shrinking) and the cold, damp upper chord (wet and swelling). This differential will not happen in an uninsulated or poorly insulated attic.

    This is why truss uplift is often worse the first winter but might recur every winter, depending on ambient humidity levels.

  17. John Klingel | | #17

    RR: OK. Does snow load factor in there anywhere? j

  18. Riversong | | #18


  19. Robert Post S.E. Pennsylvania Zone 4a | | #19

    I have a client who is experiencing a large recurring drywall crack because of this uplift. his scenario is as Robert R. indicated. The builder has patched but it comes back. What is the permanent solution?

  20. GBA Editor
    Martin Holladay | | #20

    Here's some more information on truss uplift solutions:

    If you do a Google search on "truss uplift," you'll get lots of information on the issue.

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