Decks, Patios, Porches and Docks - Need to seal Porch over basement living space

I'm looking for a product to seal my porch floor so that snow/rain, etc. does not leak into basement. I'm fixing up an old house, in Ferndale, Michigan, with a covered porch, but not enclosed, the previous owners dug out the basement under the porch, they also finished the basement with drywall.

Photo Link:
http://www.johnmogelnicki.com/Images/pages/Siding%20Old%20(2)_jpg.htm

I don't want to build a deck/floor over what's there now but plan to install some indoor/outdoor carpet that will improve the look/feel of what ever product I find to seal the porch.

I've found a 60 mil rubber and a plastic decking product that says it's durable. The porch has drains in the front, so I'll need to wrap the product up the walls 4 to 6 inches and direct the flow towards the drains. The plastic product says it's durable for chairs, etc.. but I'm looking for more options becase it's expensive and needs to be heat welded. I don't have experience heat welding.

I'm siding my house with crainboard and want do to get this porch floor figured out so I can proceed with the siding project.

The house is in Ferndale MI, so we get all temps, but I'm mostly conserned with snow drifting and melting due to the heat from basement below. Rain doesn't get in unless the wind is blowing it sideways.

Thank you in advance for any help you can provide.

John

You might want to try posting a few more pics, showing the details of where the porch drains to, which way it is sloped, and the condition of the floor. It is hard to tell exactly what you have with that picture.

I know there are people on this forum with experience in membrane roofing, etc, they may be able to help you with more information.