Hey Folks,
I was in an attic yesterday and ran across something I’d never seen before. From what I could see, there appeared to be about a 2 1/2 inch thick Fiberous-type board (I could only see this where it abutted to the access opening), covered by a solid (almost tar-like) coating with gravel (yes, rocks) on top. Most of the gravel was stuck in place, but some was loose. This covered all the bottom chords of the truss system and could be walked on. I really don’t know how to describe this. Many Thanks! Patrick Hume.
It looks like vermiculite from MI.
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Welcome back to our forum, Patrick!..Enjoy! 
Nope. Not Vermiculite. I see that regularly, probably a dozen times a year. I really couldn’t see the fiberous board I descibed (there was only about a 1/2 inch gap) at the access. The top was rocks and I couldn’t dig my screwdriver into it (but I could walk on it, gingerly of course, but there was no give to the surface when walking). It was “weird” in my book, but I thought someone may know what it was. Home built in 1958.
possibly low slope (flat) ballasted roof
roofed over with a retrofit pitched roof
the only insulation if present would require observation above ceiling tile or be encapsulated under the fiberboard in the ceiling bays requiring invasive-destructive inspection if they want to know
seen & done numerous res or comm low slope to pitched retrofits
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Hey Barry, I think you are correct! Thanks for your help!
Hi Larry, Thanks! I’m typically just a lurker, but this one had me stumped (very few flat roofs on residential properties here in Ohio, and the idea of a retrofit just didn’t occur to me). I always appreciate your (and others) thoughtful/helpful replies here on the forum.
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I agree with Larry’s assessment.
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From here it looks like a sloped roof built over a flat tar and gravel roof.
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I agree with Barry’s assessment.
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Same here! 
Well ! What type of insulation is it? 
yeah same completely agree!
I’m all bought in on Barry’s assessment. Actually, I think I should have identified it as such when I was there. Next time it will be immediately apparent to me.
This home was built in 1958. My guess is that the retrofit roof was put on fairly early in the life of this home based on the appearance of the trusses/sheathing.
Thanks to everyone for your help!
Loose stone… very poor insulator. Yeap!
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Ballast aggregate! You’re The Best!
I have no idea what that is or where the house is located but my first impression is that it looks like the home originally had a flat roof and a sloped roof structure was added to it. I know. That’s one hell-of-a fleeting first impression.
I know this is an old post, but I’m glad I ran across it. The photos look similar to what is in part of my attic. My home inspector said and documented it as vermiculite. I had a lab company collect samples to test and some for me to send to the ZAI Trust (since the trust will reimburse 50% of the removal cost). The lab and the trust confirmed it was not vermiculite, but roofing material. I’ll need to remove at least some of it as the tar and gravel extend to the eaves blocking the soffit vents.