Help with siding indentification

[Peter Daly]

Can anyone identify the product shown in this photo. It's a 3/4 inch fiberboard with a thin asphaltic layer on each side? It was used as an underlayment over studs and under stucco on a house built in Menlo Park, CA in the 1960's

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[Brandon Whitmore]

I'm not sure if this will help out any:

http://www.inspectapedia.com/structure/ ... athing.htm

[kurt]

It may not be "celotex", which is a trademarked brand name, but it's your basic celotex sheathing.

Fibrous interior, asphalt impregnated 2 sides.