Replies

1. 
   730d | Apr 05, 2020 10:32am | #1

   I can't get an orientation on that picture. Is that a rim joist ? Are we looking down? Is that a fragment of tar paper? A metal heat vent? Is that building balloon framed?

   At any rate the view we have looks like new to me in terms of no rotting or mold. I think you will get great advice here . Listen carefully to the building science guys as buildings like that can be one hundred years old and you can screw them up as you are rightly concerned about. I suspect they will recommend no or a smart vapor barrier. Depending on your budget rock wool or fiberglass insulation. Air tight drywall although that might not work well if there is a vapor barrier.

   Your approach might change if you find rot or mold in the walls cavities. Just trying to get this discussion started.

2. Expert Member
   Akos | Apr 05, 2020 11:18am | #2

   I would make sure that you have two layers of felt under the stucco. If this is the case, it is safe to insulate the wall with your choice of fluffy insulation. As extra insurance, it won't hurt to staple up some house wrap into the cavities. This doesn't apply in your case, but some good info here for insulating old houses:

   https://www.greenbuildingadvisor.com/article/insulating-walls-in-an-old-house-with-no-sheathing

   With a balloon frame house more than 50% of your heat loss is from air leaks. The important part is to air seal. This mean sealing up the stud and floor bays. Unless dense packed, insulation won't help on this front. You need to cut pieces of wood or rigid foam to fit in there and seal them in place with canned foam.

   Sometimes interior partition walls go right up into the attic without any top plates which is essentially a giant hole to the outdoors.

3. 
   user-7546055 | Apr 06, 2020 01:22pm | #3

   Thanks for the replies so far. Just some additional clarification: The photo is taken looking in to the old kitchen wall along the side of what used to be the exhaust vent for the microwave. So that's the metal exhaust ductwork that's visible in the photo. I haven't started pulling down the plaster/lath yet, so this was the best photo I could get of the wall cavity. I'll be better able to view the back side of the exterior once we start pulling down plaster/lath this week.
   I'm fairly certain it's balloon-frame, but I'll get some more photos this week and let y'all see for yourselves.

   Akos, what are the odds that they used 2 layers of felt ~100 years ago? What if I only have one layer?

   Thanks again!
   -Travis

1. Expert Member
   Akos | Apr 06, 2020 07:41pm | #4

   Travis,

   With an insulated wall you MUST manage bulk water intrusion. If there is not a proper WRB, than you need to follow the advice in the earlier link.

   There is good chance that the existing wall doesn't have the proper WRB details, this is just the price and charm of owning a century home.

   One item you must pay very careful attention to is flashing around all your windows and doors. These uninsulated balloon frame walls tolerate a lot of leaks without issues, but if you insulate without dealing with the water leaks you'll end up with a moldy mess.

4. 
   user-7546055 | Apr 27, 2020 05:49pm | #5

   So it's taken me a little longer than I intended to provide an update, but I finally got around to taking some more photos yesterday now that we've got pretty much the whole house gutted.

   General update:

   -While the house IS balloon framed, there is wood blocking installed in all the stud bays between the floors. So there probably wasn't as much air movement in the exterior wall cavities as there is in the typical balloon-framed walls that are open from the basement to the roof. I've included a photo of the blocking.

   -The vast majority of the exterior walls are in what looks to me to be amazingly good shape considering the age. As you'll see in the photos, there is some evidence of minor moisture wicking at the nails used to fasten the tar paper and stucco mesh to the sheathing. I'm not really concerned about this (should I be?).

   -There is also some evidence of leakage around windows (which I was expecting), but we're replacing all the windows, and will address these areas at that time. This is the ONLY place I've found even the slightest evidence of mold/wood rot.

   -There also seems to have been some moisture intrusion around the chimney (photo with brick in it), and at the exterior wall on either side of the front porch (this appears to have been resolved, as stucco patching is visible on the exterior in these areas and they didn't seem to be wet yesterday after 2 days of rain).

   I found a couple areas where I could poke at the tar paper barrier from the inside, and there seems to be a little bit of space between it and the stucco mesh, so maybe a small air gap there but I have no idea how consistent it is throughout the exterior.

   So, all of that being said, with the combination of the stucco and tar paper providing a WRB, and the general good condition of the exterior walls, and if I address all of the issues around the windows, what does the GBA community recommend in the way of insulation systems?
   I'm leaning towards dense-pack cellulose in the existing cavity, possibly with a 1/2" layer of foam board underneath the drywall to help (a little) with thermal bridging. Am I likely to have problems with this setup? Anything else I need to do as a precautionary measure?

   Thanks again,
   -Travis

   
5. 
   user-7546055 | May 02, 2020 06:36pm | #6

   Anybody?