Can't finish building my house

It seems like this is a bug. The UESP writes about a possible fix:

• The menu for the exterior carpenter's workbench may be blank, even if there are items available.
  • Exiting the menu and selecting the workbench again may fix this. If the problem persists, try this fix multiple times.
• The carpenter's workbenches may have items that you already have built listed as being available.
  • Exiting the menu and selecting the workbench again may fix this. If the problem persists, try this fix multiple times.

I've encountered this bug on most of my playthroughs. A lot of time I'll build the foundation, then notice the option to build subsequent parts of the base house disappear.

What I normally do to fix it:

• Make sure there isn't an animal/npc on the building plot. A lot of times butterflies/rabbits are the culprit. If it's trapped under the foundation, sometimes a Fus-Ro-Dah can clear it.

• Sometimes leaving the work bench and running onto the foundation,
  then back to the work bench fixes it for me. I'm unsure if the object moves by the time I get to the foundation, or if there is a mod that isn't rendering/updating items outside of the players view and this action causes it to update. I've found this method more reliable than constantly exiting and re-entering the menu.

• If all else fails, fast traveling to another location, waiting an extended period of time (48hrs?), and fast traveling back seems to fix it (7/8 times for my game).

If you remove and re-add the workbenches you should get the option to add anything that’s missing or glitched.