Vol 24.18 - Teitzei 2

Summary

(5741) Sifrei(22:8): "a house - to include the Heichal (for a guard-rail), even though: "'your roof' - excludes the roofs of Synagogues and Houses of Study" (Talmud Chullin 176a) - according to halacha and in Avodat HaAdam

 A roof, being the highest part of any structure, alludes to the ego, which gives a person an elevated impression of himself.

Thus, in order to prevent a person from falling off his roof by allowing his feelings of swollen self-esteem to degenerate into selfishness, we are warned to make a guard-rail for your roof - to carefully control and temper the ego with guard-rails.