>>2580438When building underground, you can measure and chop local wood for support structure inside. Lining the wall with wood to support a ceiling is good for underground building. You can even do carpentry with wild wood, like stripping and splitting the logs.
If concealment is not an issue, consider building with stones. You can use wood planks for flooring, and stones are good for furnaces and chimneys. You will need shelter and heating to survive the winters.
