Q: The concrete steps at my house are moldy and kind of green on the risers, except where I applied a concrete sealer. I did it badly, so you can see areas that look like drips. How can I safely clean ...

Q: I want to wash black mold from a concrete wall next to plants. Can I use dish detergent and a hard bristle brush instead of a power washer? The water will be running to the plants, so what kind of ...

A different conversation about the capabilities of 3D-printing is happening at edg, a New York architecture and engineering firm which focuses on technology-driven design and the restoration of ...