I am adding a year-round roofed porch to a small house. The porch will be 10 ft. wide x 20 ft. long. the entire back of the house. I am using slider windows, 4w x 5h. I am wondering what my choices would be for the foundation. A concrete slab would be more weather-proof than decking, but are there any other alternatives?

The porch will be entered from the house by a sliding glass door, already installed.

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