Give every big idea a foundation
Mark out the footprint and choose your ground contact points first. Think through where the main supports will go before extending the roof or adding a second floor.
Build a small test section using the materials you actually have. Inspect it with the hammer and pay attention to the game’s support feedback as you extend it.
Change one thing, check again
Add the structure in stages so you can identify which change caused a problem. Avoid covering your supports until you are happy with the shell.
Gunnar’s answer may be more core wood, but the useful question is where that wood connects and what it supports. Inspect the connection, then test the next section.
Before the grand reveal
Walk the perimeter and inspect awkward corners, long spans, and upper floors. Keep a materials reserve for the fix you discover five minutes before filming.
These are workflow notes, not exact span or material-strength tables. Check your build in your current game version and mod setup.