So, we recently had a new porch (deck, technically) put on our house. We have an under-porch storage area, that with the old porch, wouldn't have rain come through, as there were no gaps in the wood, it was more like a wood floor. On the other hand, this new deck has wood gaps, so water gets down in the storage area, and makes the ground muddy, and our bikes, my daughter's stroller, etc. are susceptible to rust. Now, normally, we would keep these things in the house, but the storage area is towards the bottom of the house, and there's 60 stairs to the top, so it's just not practical. What I'm interested in, if I could, in the future, tear down the wood deck and replace it with a concrete porch, and if that would be difficult. Here's pictures of the deck and the under-storage is right below it, where the rocks are.

Anyways, the contractors didn't realize/pay attention, so yeah, we want to prevent the rust/mud issue, so I'd like to replace it with a concrete porch at some point and time, if that's possible. Basically, it's joists and crosspieces supporting the deck, and I don't know if I'd need to take those out altogether, or how simple or difficult the whole task might be. The house itself is over 100 years old, and that stone setup is essentially the foundation of the house.

Any input would be appreciated.

Here's a Mercedes Ocean Drive for your time.