(hotfix) Patch 1.13.2 - Fix timber framing under roofs

Howdy! Just a quick fix here. In the process of allowing buildings to go lower in 1.13.0, we accidentally broke timber framing under roofs. Sorry for the breakage - it's managed to sneak past our automated tests.

Here's the broken version:

And here's how it should look like:

Thus, the change list:

• 🐛🦜 Unshiver me timbers

Thanks for the bug reports <3

Love, Tom & Ana