MB4 219b: What is Needed as a Fourth Wall (363:2-5)

If the entire fourth wall of a chatzer fell down it needs a lechi if there is less wall than breach. The breach needs to be corrected until it's less than three tefachim. What if the breach is larger than ten amot?

How to enable carrying in a mavui that is enclosed on 3 sides via a lechi.

A lechi that can't stand up to the wind.