Has anyone ever seen this kind of construction? Stucco-Mortar-Cork-Plaster!

We have a 1926 built English Tudor style home that is proving to be a rather unique animal. We are attempting to add a first floor bathroom as an addition to the house and I have just begun investigation into the construction. The cross section of the exterior walls of the home appears to include the following (from outside surface of the building to the inside surface of the building):

-Stucco ~1.25" thick
-Tan colored mortar ~5" thick
-Cork ~1.5" thick
-Plaster ~0.25" thick

I haven't opened up a big enough hole to determine if there is any metal lath that exists between the cork and the exterior stucco, however the 1/2" masonry bit didn't encounter any metal while drilling from the interior of the house to the exterior I stopped at a depth of 7" as I did not want to break thru. The overall walls appear to be about 8" thick while viewing an exterior door jamb or window opening.

I have drilled two test holes, one at 12" up from the floor and another at about 48" up from the floor. I expected to find a hollow space somewhere, and I did not. I also expected to find that the exterior stucco would have been applied to metal lath which would've been attached to sheathing and this is also not the case.

While in the attic looking for clues, it is evident that the gable ends of the house in the attic area are simply 1.5" cork panels that appear to be cast in place with the exterior concrete and stucco, I can see some seepage at the edges of the cork panel (which are about 24" x 48"). In one area the squirrels scratched away the cork down to the concrete, there is no wood.

I did cut a 12" x 12" chunk of an interior wall out on the second floor of the house and it was clear that in this case the 1.5" cork had been nailed to studs and then coverred in plaster. The cielings on the second floor are also confirmed to be plaster coverred cork (which has some sagging between the 24" on center "rafters").

Was cork ever really used for homes in the past? Before I continue opening up the hole in the wall looking for studs, has anyone ever heard of pouring first floor exterior walls of a home?

Also, another interseting point is that the beam which supports the first floor joists (visible from the basement) is a poured concrete beam. The joists at both the midpoint of the house along this beam and at the perimiter of the house on the foundation (which is poured concrete) all appear to have been cast into place when the concrete was poured. The tails of the joists are visible from the underside of the beam, where they are embedded into the concrete beam.

Seems like we are living in a bomb shelter.

One final point was that while having a new water service quote from a local plumbing company, the old timer who came out to do the estimate said that he had known a few previous owners and that allegedly the original owner had built the home fire proof, I plan to contact him tomorrow to see if I can find out anymore history.

Any information related to this seemingly one of a kind odd-construction technique would be helpful, as I am currently drawing up plans for submittal to obtain permits. I have a hard time accepting that to cut the hole in the exterior wall where we will enter the bathroom that we will be removing a solid chunk of this stucco/concrete/cork/plaster recipe!

Thanks,
Ben

Welcome Ben:
It sounds a little like those straw bale, stack wood, can and bottle, or tires filled with dirt type of houses. My first employer at the lumber yard used to say, "To itch his own, and he sure itched his".
It will be an adventure for you to build onto this one. We would appreciate several pictures.
Glenn

Cork was used as an insulation until the late 60's early 70's in industrial applications. Most often in refrigeration situations. To the best of my recollection, never more than 3" thick, unless large walk in coolers were being made. It seems as though the builder had access to, or knowledge of working with, cork. With good seals at any openings, you should feel as snug as a bug in a rug. Armstrong was one manufacturer who used it, and after the 70's came along, cork disappeared as an insulating material.