It is forbidden to “mosif al habinyan” by attaching to the wall, material that blocks entrances and windows. Adding bolts and pins to secure doors from opening likewise is forbidden. Nowadays, most houses have built in doors and windows with built in crossbars and security locks and bolts. The holes that they fit into are also prefabricated for this fitment. Even loose ones that have handles are deemed as kelim. It is not the derech for these objects to stay permanently in their corresponding holes or entrances of the building and therefore not ossur as Boneh. (ShA 1, 2 – MB 21, 22)
You aren’t allowed to assemble pieces of a put-together kli, unless the pieces are meant to fit in loosely (i.e. they still move inside their hole). (ShA 6 – BeH “darkah”)
Lids that fit tightly on kelim are allowed to be taken on and off since they are meant to be opened and closed constantly. (MB 45)
Inserting a wooden handle into an axehead or driving in a peg to tighten the handle is a subcategory of Boneh. Taking it apart in order to refix it is a subcategory of Sosair. (MB 54)
Spreading sand or gravel onto a muddy (yard) walkway is ossur. You are allowed to spread material that will not remain there. Animal fodder, for example, does not stay part of the ground. (However, you must spread it with a shinui because of uvda d’chol.) (ShA 10 – MB 55, 56)