MB4 219a: Arches as a Tzuras Hapesach (362:11-12); Lechi (363:1-2)

The sideposts of a tzuras hapesach need to be strong enough to hold doors; the horizontal post can even be a string but needs to be taut. Some achronim are machmir that the top has to be very tight.

Dimensions required for an arch to be a valid tzuras hapesach

Minimal width of a tzuras hapesach.

מדאורייתא, one can carry in an area enclosed on three sides (e.g. a מבוי) but מדרבנן it requires a לחי

A v-shaped enclosed area

If the fourth wall of a חצר came down.