Shabbos 10:11

If a person connects paper or hides using the kind of glue used by a scribe or similar adhesives, he is liable for performing a subordinate labor of sewing. By the same token, one who separates papers or hides that are attached in such a manner is liable for performing a subordinate labor of tearing unless his intention is purely destructive.

Shabbos 10:12

One is liable for building even the smallest amount. Leveling a dirt floor is considered building and renders one liable, whether he lowered a place where the earth was elevated or filled a hole. If one person puts down a stone and another applies mortar, the one who applied the mortar is liable. When it comes the highest row of stones, a person is liable for placing the stone on the mortar because mortar is not placed on top of it. One is not liable for building onto utensils.