I have a tongue and groove wood porch that is in Cleveland, Ohio. It is covered, but rain and snow do sometimes land on the porch. There is no subfloor so this is a real problem in the winter. Cold air comes into our basement through the porch. If I hose down the porch for spring cleaning, water comes through the boards and into the basement.

What is the best way to fix this issue?

I was thinking of either replacing the boards with the trex material, but not sure if I need a subfloor down first. If not, how do I fix the loss of heat and moisture into the basement.

I was also thinking of ripping up the wood and building a form and pouring concrete.

What would be the proper way to ensure that our basement will not get cold and to keep the moisture out?