Hi I recently purchased a 1916 Victorian home and the front porch is need of repair/replacement. The front porch is built on the house stone block foundation and is open to the basement below (slopes from front to back, where the front is dirt and back is a finish basement) as well as the floor joist. It is your typically tongue and groove painted flooring which I assumed was a original to the house and is laid/installed on the house floor joist. After further investigation the tongue and groove isn't the original douglas fir or pine flooring. It has been replaced, my guess within the last 5+ years, and was laid over a plywood subfloor with a roof membrane over that than the T&G decking was installed over that. They probably thought this was a great idea as it sealed off the basement and floor joist but in turn created a space where water can collect and rot the T&G from the bottom up. I had a carpenter come by my house today to give me an estimate to have this replaced. He suggested to install AZEK T&G decking over the plywood subfloor with a ice and water shield.

My question is two fold:

1. Is this the best solution to install a PVC T&G product over a the plywood subfloor with a ice and water shield membrane
2. Or, from what I read, is to remove the plywood subfloor and install a T&G either douglas fir or a hardwood such as IPE directly onto the floor joist?

Again this is open to a dirt basement below on the front of the house and slopes down to a 8' floor to ceiling height completed basement.

I apologize if this has been asked before but all the forums I've read about this subject is "the porch shouldn't be open to the basement below". I'm sure that's not common practice today but they obviously did this in the past. Any help or suggestions would be greatly appreciated.