I just went up into my attic (house was built in 1939) and found that there is black paper on the 'walls'. Part of the reason for going up is to find out the back of holes that my electrician made while mounting something to the outside of my house.

What is the function of this black paper? What if there's a hole in this black paper? Basically I can see to the outside of the house. The hole is about 1.5" in diameter. How do I patch it?

Here are two pictures. One is with the black paper flap down, the other is with it up. I feel like there is black paper, then some sort of plaster (with metal wires) and then stucco on the outside? I don't see insulation. All around there is black paper...except for the roof. I see some sort of foil type of material. Attic hole black paper down Attic hole black paper up

  • Is there cellulose insulation inside of it? I've run across a couple old houses that were insulated with tar paper "batts" that sandwiched cellulose between two layers of felt. – Comintern Jun 25 '16 at 0:29
  • Tired today but think 30-45 pound felt was for siding the heavy felt 100, -40 or what it was, was for roofing ,, – Ed Beal Jun 25 '16 at 2:27
  • What's behind the paper? Is it a fiber board? Wood? If it's something soft you can nail a board atop it, that will stop creatures from getting in. – Chris Jun 25 '16 at 2:31

To this day tar paper is used as a moisture barrier under masonry products and roofing on the outside of homes.

You correctly identified the layers from inside out, tar paper, metal lathe, stucco. To repair it you will need to remove the damaged product and replace the layers.

Check the Internet for videos on repairing damaged stucco.

Good luck!

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Older homes usually had a layer of "tar paper" on top of the roof sheathing (plywood or OSB) and underneath the roof shingles. This paper was intended to be a "water resistant barrier" so that water or ice that migrated under the shingles would not soak the sheathing. Water-soaked sheathing will mould or rot, and create a health or safety hazard.

But I don't know what a layer of tar paper inside the roof would be for. Could be someone thought it would be a good idea to create a vapour barrier, before the common application of roof venting to control moisture?

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  • Judging from the colour and shape (square cut lumber) I would imagine the house is pre-1970's, they would have used it as a version of house wrap to cut airflow. Generally applied inside between the brick and lats (or lumber). – Chris Jun 25 '16 at 2:28

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