Placing a unattached plastic over the stroller on Shabbos / Yom Tov

Question

According to Rabbi Dovid Ostroff Shlita

The Rama in Hilchos Succah 626:3 says that one is permitted to open and shut hinged flaps that are used for covering the Succah when raining. The Chazon Ish 52:6 learned from here that this would likewise apply to a canopy connected to a baby carriage. Since the canopy is attached to the baby carriage before Shabbos, it has the same status of being open a tefach before Shabbos and one is permitted to fully open the canopy on Shabbos. The same would apply to a canopy covering.

Igros Moshe Orach Chaim 4 - page 194, Ohr L'tsion however do not agree to this analogy and in order to permit the extending of a carriage’s canopy on Shabbos they require the canopy open a tefach before Shabbos. As usual one should therefore ask one’s rav as to how to conduct oneself on Shabbos. Rav Sternbuch Shlita said that the custom is to be lenient.

My question is regarding a unattached plastic cover which people use when it is raining. What would be the Halacha with such a plastic? Igros Moshe Orach Chaim 5:39:4 says that one may put a plastic cover on top of a succah on Shabbos. This is not called "construction", because the cover is clearly temporary. Would one be allowed to open it and place it on top of a stroller on Shabbos and/or Yom Tov as it is also clearly temporary or is it considered an Ohel and prohibited?

Answer 1

Shmiras Shabbos Khilchasa (quoted by Rabbi Ribiat in his Sefer 39 Melachos) page 154-155 says it is permitted to add to a Ohel on Shabbos and therefore one may place a plastic covering over a stroller on Shabbos, so long the strollers own canopy is open already. He says the regular canopy can be opened as it is attached and then you place the plastic covering.

Answer 2

from http://doseofhalacha.blogspot.co.uk/2014/03/buggies-strollers-on-shabbos.html

The Shulchan Aruch (OC 315:1) writes that Chazal forbade making a temporary ohel on Shabbos. The Gemara (Shabbos 138a) writes that one may unfold a folding chair on Shabbos. While doing so creates a shelter over the space underneath the chair that is not considered making an ohel. Thus, it would be muttar to open buggies and foldable cots on Shabbos (Shemiras Shabbos Kehilchasa 24:23)

R’ Yechezkel Landau (Noda B’yehuda OC 1:30) writes that umbrellas are not included in this category and may not be opened or closed on Shabbos. While many Acharonim (Chasam Sofer OC:72; Tiferes Yisrael, Kilkeles Shabbos, Ohel) disagreed with R’ Landau’s arguments, they did not allow their use.

Following R’ Landau, R’ Moshe Feinstein (Igros Moshe OC 4:105:3) and R’ Ovadia Yosef (Yalkut Yosef, Shabbos 2:p536) write that the hood may only be closed (unfolded) providing it is already open a tefach as no new ohel is being created. Likewise, when opening (folding) the hood, one should not open it fully, though leave one tefach closed to avoid dismantling the ohel.

The Chazon Ish (OC 52:6) compares buggy hoods to sukkah roofs which the Rema (OC 626:3) allows opening on Shabbos. As the hood is already attached to the buggy, one may open and close it fully on Shabbos. Most contemporary Poskim follow this view. R’ Yehoshua Neuwirth (Shemiras Shabbos Kehilchasa 24:13) and R’ Ribiat (39 Melochos p1079) write that if the buggy’s canopy is closed one may spread a rain cover on top.