A fundamental element of an eruv is the tzuras hapesach, which is defined here as, "[a] doorway opening. The construction of two doorposts and an overhead lintel." Can one make a tzuras hapesach arched or does it have to be straight?

I know there are many authorities who discuss the lechi (post) and korah (crossbeam) being straight, but many doorways have an archway; does anyone discuss whether designing a tzuras hapesach this way would be valid?


Indeed, as SethJ and ShmuelBrin noted in their comments, the Gemara (Eruvin 11b) discusses such a case. Shulchan Aruch (Orach Chaim 362:12) summarizes it thus:

כיפה, אם יש ברגליה דהיינו קודם שהתחיל להתעגל י' טפחים, מותרת משום צורת פתח

"An archway, if its legs - before it begins to curve - are at least ten tefachim tall, then it is permissible as a tzuras hapesach."

(The point that emerges from the Gemara there is not that the curve is considered as if it were straight, but that we ignore the curved part altogether, and consider the top of the tzuras hapesach to be the horizontal line tangent to it - the top and the sides don't have to touch, so long as they are aligned correctly.)


The answer I think is no. But there are halachic considerations like lovud and 'chavut' which in certain circumstances consider curved things straight.

  • But it looks like a pesach
    – sam
    Apr 21 '13 at 17:16
  • I don't remember which daf, but I recently learned a Gemara in Daf Yomi that suggests to me that Meir is probably correct. Halachah LeMa'aseh, CYLOR, of course, but I'm pretty sure it's a problem. I believe, though, that the Gemara also offers a possible solution, where we imagine it's straight for measuring purposes, but again I don't know the final Halachah.
    – Seth J
    Apr 21 '13 at 20:33
  • @sethj you're thinking of the lechi or of the tzuras hapesach re. Mezuza (chokekim lehashlim)? Apr 22 '13 at 5:18
  • @Shmuel brin I think you might be right.
    – Seth J
    Apr 22 '13 at 12:21

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .