My house was built in 1928, its an old Milwaukee bungalow. I have a small cantilever overhang in the front of my house. That area gets pretty cold in the winter, so I wanted to investigate insulating it.

I cut a hole through the sheathing underneath and it seemed to contain some sort of stone or concrete. Has anyone seen anything like this?

My main question is how can I insulate and/or seal this overhang? I incorrectly assumed the inside was empty or poorly insulated, so I could open it up from underneath and add some insulation. My only idea is to:

  1. Take off the exterior sheathing
  2. Put in sheets of XPS
  3. Use spray foam around the edges of the XPS
  4. Put in new exterior sheathing. I'm assuming this sheathing will come down to that lip around the edge of the overhang.

Here are some pics...


Interior view


Exterior view

How I think the cantilever is constructed; I'm looking to insulate the yellow part

Possible contents

Small amount of contents of overhang. Yeah, that appears to be a stone. Overhang contents

  • Which part are you thinking of insulating? Under the upstairs floor, or the top of the exterior first floor wall? – wallyk Aug 31 '16 at 3:54
  • Use a sharp knife on the suspected mortar and try to lift up like 1/8 inch of it.. Does it have a fibrous structure? – wallyk Aug 31 '16 at 3:54
  • @wallyk looking to insulate the exterior, underneath the overhang. I figure that is the easiest thing to access. Also, this overhang is on the first floor. Regarding the suspected mortar, I added a photo. Doesn't seem to be fibrous to me. Are you suspecting it could be asbestos insulation? It does seem odd that the overhang would contain concrete. Though the floor does sag a little over there. – Jason Capriotti Sep 1 '16 at 10:39
  • I know on some homes the surface above a brick or stone wall had a skim coat of mortar, this allowed less expensive sheeting to be used and did not require painting as often. I have seen full blown stucco to a very thin 1/8" coat directly applied. – Ed Beal Sep 1 '16 at 13:32

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