This post has some misleading comments regarding ecocork. I am investigating underlayment for vinyl plank. If you look at the actual test results from NGC testing services for the delta IIC of quietwalk LV, floormuffler lvt encore, and ecocork, they are all tested using the same 6 inch concrete slab (not 8 inches). The IIC and STC have other included materials in the test like insulation, gypsum ceiling, etc. But the delta IIC has only the concrete slab and measures the difference in sound dampening with and without the concrete slab in place telling you the true dampening of the underlayment itself. By this measure the quietwalk comes out on top with a delta IIC of 28, ecocork at 23 and floormuffler at 22. If you look at the frequencies, you can see that the quietwalk is the only material that has some degree of dampening of the lowest 100 hz tested around 5 db. The testing is slightly different in that the quietwalk was tested with a 5 mm vinyl plank on top whereas the ecocork was tested with a layer of engineered wood on top. The thickness of the engineered wood was not given. Floormuffler does not have a link for the actual test results. This article has a helpful explanation: https://arcacoustics.com/2016/08/23/stc-iic-delta-iicwhats-this-all-about/

Maybe think of your porch floor a little more like a roof ... I, too, have an old house with incorporated porches (front and back) that sit over top of a full basement foundation (brick with original stucco.) We restored the back porch as a "sunroom" (it was closed in some time in the 30's) and I noted that roofing tar paper was used between the sub floor (plank) and the original T&G porch floor. There are shreds of roofing tar paper hanging on the edges of the bottom of the front porch floor where I can find it, but the old wooden floor was replaced with plywood and then the porch floor was tiled by POs (a bad DIY with 1 inch grout lines that leak like crazy, making my repair job that much more difficult.) The pitch on both porches is good (away from the house) There are low shingled walls all around the porches so water would be trapped without some sort of system to remove it. The front porch uses a pitched trough with 2 exit tubes at the foot of the short wall but I found no evidence of this on the back porch. These 2 devices (the roof paper and the trough) surely would have worked well if they were maintained, alas, the metal trough is rotted thru and leaves/critters were getting into the basement till I discovered the holes and band-aid-patched them till I can address repair of the trough properly. (interestingly, the front porch foundation was hidden behind a finished wall in the basement and was only found when we had a termite inspection done.)

This "tuff rubber " product is unknown to me as a membrane they do make boots I have used. Your pictures show something already on the plywood. If this were my job to bid >>> Torchdown modified or cpo roof over the plywood, ground contact pt stringers laying in the direction of the flow, screw the decking to the stringers not past them into the roof. Do not fasten the T&G decking with a nailer. Using Construstion adhesive on the joists and stainles steel screws run the screw thru the G. Do not place this decking the same way you would fasten a floor inside your house. Reread. Again. One More Time. Request your Roofer Contractor flash and roof over any drain holes you cut in that plywood. The drain system you are thinking about is flawed. Data,you might just have come to the right place your total plan will come back to bite you really hard in a short time. John Hyatt www.deckmastersllc.com

" Just curious, if a "full basement foundation" is built on grade, how is it a foundation rather than a first floor/ground floor?" If you can dream it, it can done. My intention was to artificially raise grade, by grading up to the 13' higher second floor, making the second floor appear as a first floor, which would no doubt require thousands of yard of dirt but I had access to free dirt; the size of the lot made it feasible. Visually it would appear as a raised home or on a hill, with a driveway leading up; not an uncommon sight when I lived in NJ. I was keen on a full basement to accommodate a couple of bowling lanes, something I may vaguely consider building as a separate inconspicuous structure somewhere on the lot, however there are other important things at hand now, like completing interior design and renderings; these are close to getting finished, just need to complete designing builtins around the fireplace then the walkin pantry to DW's specific requirements.