I'd like to Build a Cold Frame on Contaminated Soil. What should I lay mulch, compost and new top soil on?

Question

I'd like to Build a Cold Frame on Contaminated Soil. What should I lay mulch, compost and new top soil on?

Answer 1

How contaminated, with what?   Newspapers, plastic, some old plywood/boards would all work, depending on how much of a barrier you need.

Answer 2

I can't claim to even know what a "cold frame" is, but I do want to ask you this:  why not build it somewhere else, where the soil is NOT contaminated?

Answer 3

Contaminated soil?  fungus, or chemical?

If the former, you only need to have enough organic to provide a root zone base for whatever plant you plan on cultivating (generally 2 feet deep), but the fungus will eventually migrate into the new soil base.

If chemical, you would use an impervious sheet of plastic, and then build the new bed on top of that.  as long at the base sheet is not punctured, you wouldn't have to worry about substrata contamination of the new bed