May a person build a projection over his neighbor's airspace without permission?
No one may build a projection — regardless of size — over a neighbor's airspace without permission. The neighbor's airspace is legally his own.
Question 2
If a projection one handbreadth wide has been in place long enough to establish a right, does that right extend to widening the projection?
A right established for a one-handbreadth projection covers only that width — widening the projection requires establishing a separate new right.
Question 3
If a person extends a drainpipe over a neighbor's courtyard and it has been there for many years, does it create a permanent right?
Unlike projections, drainpipes do not establish permanent rights regardless of duration — the neighbor can always demand the pipe be removed.
Question 4
If a person has an established right to insert one beam into a shared wall, how many beams may he insert?
The right to insert one beam is specific — it does not permit inserting a second. Each beam requires its own separate right.
Question 5
When one of two partners builds a wall without the other's participation, who has the right to insert beams in it?
A wall built by one partner alone belongs to that partner alone — the other cannot insert beams or use it without the builder's consent and compensation.