I Don't Understand This Roof

[bananamber]

Let me start off with saying I'm not too experienced with roof repair. A few weeks ago, I noticed the corner of my roof's overhang was collapsing, so I finally decided to address my admittedly bad roof. I got up there and started tearing away the rot and discovered my roof is asphalt shingles over cedars shakes over plank decking (The shake are wet rotted). I don't even think there was any moisture barriers. But here's what really messed with my brain, in the first picture you see drywall between the rafters. There is no drywall visible in my attic. Additionally you see insulation. No insulation is visible in my attic except between the joists.

I haven't ripped out all the rot yet until I set up a scaffold plank to work from, but as far as I can tell, the drywall and insulation run all the way to the peak. Again, neither of those are visible inside the attic. Inside the attic I only see rafters, plank decking with much smaller gaps and shakes over that.

This house was originally built around 1870. This part of the house sometime between then and 1920 and then renovated in 1958.

I simply don't understand this roof. Is it literally a roof built on top of a roof built on top of a roof?

 

[Steve123]

You did not explain your situation very well. I am only seeing one image, which doesn't really show me anything.

Rather sounds like your attic is a finished room with drywall, including on drywall on ceiling/rafters ?

But you are able to see the insulation. but you are not able to see drywall.

Roof should normally be ventilated. I take it you have no ventilation ? That is a problem. (I think some claim there are ways to successfully do a roof without ventilation (hot roof) but that is beyond my knowledge.)