Title says it all.
When opening the 'build' signpost with a 'craft' menu open, you will only apply build materials up to the amount of materials needed by the 'craft' recipe.
Specific example: I am building a Curding Tub. I have four boards in my inventory. With the bucket crafting menu open, I can only build 2/4 boards required until I receive an error stating 'you have no applicable building materials', even though I have two more boards available in inventory (highlighted green for the Crafting recipe).