Though there are many important and in-depth halachot pertaining to the mitzvah of mezuza, this article will focus on the halacha of mezuza as it pertains to an elevator. Through this case study, we will clarify some basic principles concerning this mitzvah and gain some insight into its inner workings, as understood by the Rishonim and later poskim.
The Minimum Size of the Room
A baraita cited by the Gemara states that “בית שאין בו ארבע אמות על ארבע אמות פטור מן המזוזה” – a house that is less than four amot by four amot is exempt from having a mezuza placed on the doorpost. When the Gemara explains why such a house is exempt, it clarifies that “בית כתיב בהו בכולהו,” “house is written about all of them” – i.e., the Torah has taught us to place a mezuza on our home, or a place that is defined as a home, and any place smaller than four amot by four amot is not considered a “home.”
The Sages understood that such a small room does not contain basic living requirements or functions. There is a dispute among the Rishonim whether each wall has to be at least four amot or whether only the total area must be equal to four by four amot (i.e., 16 amot squared), even if one wall is shorter than four amot.
The Rosh quotes the Rif as stating the following novelty:
גרסינן בסוכה ת”ר בית שאין בו ארבע אמות על ארבע אמות פטור מן המזוזה ומן המעקה וכו’. אף על פי שבכל הספרים אין כתיב כן אלא בית שאין בו ארבע אמות. רב אלפס גרס שאין בו ארבע אמות על ארבע אמות. דמסתבר דלא חזי לדירה בענין אחר.
In this passage, the Rosh points out that the baraita only mentions four amot once, and the Rif adds a second time “four amot by four amot.” The Rosh opines that the Rif understands that each wall needs to be at least four amot to be defined as a “home,” and a total area of sixteen amot squared is insufficient.
The Rambam first presents the basic halacha and then adds that “if it has four amot by four amot, even though it is round or has five angles… as it has four amot by four amot, it requires a mezuza.” According to the Rambam, the critical factor necessary for the room to be subject to the obligation of mezuza is to have 16 amot squared.
The Shulchan Aruch rules in accordance with the Rambam that if the room contains an area of four amot by four amot, it requires a mezuza, even if one of its walls is less than four amot.
Small Rooms that are Still Functional
The Rambam’s pesak, which does not focus on specific measurements of each wall, but rather on the total area, lends itself to speculation as to whether the necessary minimum measurements are merely an assessment for functionality or are also a defining factor. For example, a laundry room is used for storing a washing machine only and nothing else, and has fulfilled its functional purpose even though it is smaller than four amot by four amot. Does such a room require a mezuza or not according to the Rambam?
One understanding is that the four amot is only an estimation of a general room size that is functional, but a room that is functional even though it is smaller would still require a mezuza. In halachic terminology, we would say that the area described is only a “siman,” or indicator, of a functional room, and is not inherently necessary to require a mezuza. Another approach is that the Sages taught us that the size of a halachic room is absolute and anything smaller than four amot by four amot is not considered a “room”, even if it is usable.
The Chamudei Daniel quoted in the Pitchei Teshuva writes that places that have a designated purpose require a mezuza even if they are smaller than four amot by four amot, a position that is relevant for lobbies, balconies, gardens and more. It seems that the Chamudei Daniel adopts the first explanation of the Rambam as explained above.
The Pitchei Teshuva adds that any large house with small rooms inside used to store objects requires a mezuza, regardless of their size.
According to the Chamudei Daniel, the critical question with regard to the minimum size of a room subject to the obligation of mezuza is whether the room is useable or not. The answer to this question is dependent on the type of room it was designated to be: Is it a room like most rooms in the house, such as bedrooms, living rooms, etc., and the fundamental requirement is that it can be used for living purposes? For these rooms, the Sages gave a measurement – four amot by four amot. However, other rooms intended for specific uses have no minimal size as long as they can be used for their specific function, in which case they would require a mezuza.
Elevator: A Stairwell, Small Room, or Car that Rises?
Although most elevators are smaller than four amot by four amot, we have seen above that this is not an absolute reason to exempt them from requiring a mezuza. However, there are other issues that need to be discussed notwithstanding the size of the elevator.
- Is an elevator considered a room in its own right, or part of the room from which one enters?
- Are the elevator’s doors considered an entrance from the room to the elevator or an exit from the elevator to the room?
- Some elevators have two layers of doors – one connected to the wall of the building and another that is part of the elevator itself. Is there a difference between these two types of doors?
Rav Yitzhak Weiss zt”l dedicated several responsa to the requirement of installing a mezuza in an elevator. In a responsa from 5724 (1964), he relates that people in Israel who began building four-story homes with elevators asked him if the elevators required a mezuza. The questioners thought that the elevator should be exempt from a mezuza “like a ship,” which is mobile, and their question only related to the permanent door before the elevator.
Rav Weiss begins his response by determining that there is a halachic connection between the obligation to place a mezuza in an elevator and the obligation to place a mezuza in the permanent door that faces the elevator. In his words, “if we were to decide that the elevator is exempt from a mezuza, this would be sufficient … to also exempt the permanent door, which is used only for entering the elevator, from a mezuza.”
Further on in his responsa, Rav Weiss adds another novelty: “The elevator must be considered in its own right to require a mezuza, because it is a beit sha’ar… even if it does not contain four amot by four amot.”
By way of background, a beit sha’ar is explained by Rav Yehuda in the Gemara to be a kind of lobby open on both sides: On one side it is open to the house, and on the other it is open to the garden, and it requires two mezuzot, one at each opening. Why was there a need for this ruling? The answer is that we might have thought that the beit sha’ar becomes secondary to the house, and as such the opening from the yard to the beit sha’ar will be exempt from the obligation of mezuza. Rav Yehuda therefore states that the beit sha’ar is not secondary, and both openings require a mezuza. In this context, it is worthwhile to remember the Chamudei Daniel‘s chiddush8 that a beit sha’ar requires a mezuza even if it does not contain four amot by four amot, because it fulfills its purpose.
The novelty brought by Rav Yitzchak Weiss is extremely logical: Since the elevator transports people between the various floors of the building, we should treat it like a beit sha’ar, i.e., a lobby between the various areas, and the elevator should require a mezuza, even if it does not have four amot by four amot, “as it is suitable for its purpose.”
Accordingly, one would require a mezuza both on the elevator door itself as well as the door frame of the area entering the elevator, similar to the beit sha’ar that requires a mezuza on each entrance. Nevertheless, Rav Weiss rules to place a mezuza on the opening of the elevator without a beracha in consideration of other poskim who hold that the elevator is exempt from a mezuza.
Rav Natan Gestetner initially writes that the elevator has the status of a beit sha’ar similar to the approach of Rav Weiss, but then adds an interesting explanation: The reason a beit sha’ar requires a mezuza is because it is secondary to the house, and not because it requires a mezuza in its own right. He claims that even though one of the conditions for placing a mezuza is that the house is suitable for human living (and in order to make it suitable for human living, Chazal ruled that it should have four amot by four amot), a beit sha’ar is different, as it does not require a mezuza in its own right, but because it opens to a room that requires a mezuza, and it is therefore considered the beit sha’ar of the room that has four amot by four amot. For this reason, the elevator door itself should require a mezuza only because the lobby it leads into requires one.
Rav Gestetner then introduces another novelty. He notes that while the elevator goes up and down, its opening is blocked and it functions only as a room. Therefore, he exempts the elevator door from needing a mezuza, because it is not considered a beit sha’ar during this time, but an ordinary room, which requires a mezuza only when it measures four amot by four amot. In other words, Rav Gestetner’s opinion is that an elevator sometimes acts as a beit sha’ar, while at other times it is considered a regular room. Consequently, it does not require a mezuza.
On the other hand, he regards the permanent entrance of the building into the elevator as a “derech kenisa ma’aliyata,” a proper entrance to the floor, so even if the elevator is exempt from a mezuza (i.e., when it does not have four amot by four amot) the permanent opening still requires a mezuza “in the exits from the elevator on all floors.” Thus, he rules that if the room to which one exits the elevator does not have four amot by four amot, one places a mezuza without a beracha.
To summarize Rav Gestetner’s opinion, the elevator is considered a beit sha’ar, similar to the opinion of Rav Weiss, but the fact that the opening is blocked renders it a normal room as well and prevents us from reciting a beracha if it is less than four by four amot. The openings in the building’s walls are considered entrances to the floor or a room and require a mezuza, and if the floor or room are four amot by four amot, one must recite a beracha on this mezuza. Regarding the lower floor, there is concern whether the passageway between the elevator and the floor are considered as if one is passing between different rooms in the house, which me’ikar hadin is exempt from a mezuza and one never says a beracha on this mezuza. Based on this opinion, we would conclude that one who enters an elevator will find himself surrounded by mezuzot, both on his right (on his right when entering the elevator) and on his left (on his right when leaving the elevator).
Other poskim compare an elevator to a stairwell. The Gemara discusses a “coop that is open from the house to the attic” and quotes Rav Huna who says that if it has one opening, it requires one mezuza, and if it has two openings, it requires two mezuzot. Rashi explains that there were houses with two floors with a stairwell in the middle surrounded by four walls “so that a person would not descend from the attic into the house without permission.”
Rav Huna’s claim is explained in the following manner: The small room that is located around the stairs requires a mezuza, so if there is an opening in the lower floor, it also requires a mezuza, and if it has one on the upper floor, they both require a mezuza. The Shulchan Aruch codifies Rav Huna’s ruling.
In light of this issue, Rabbi Yaakov Blau writes that “there are elevators today that are exactly like the coop described by Rashi,” and the only difference is that in the case of the Gemara, the person ascends the stairs on his own, while in the elevator, “there is another force pulling him up and down.” Based on this, Rav Blau states that “the openings in the building around the elevator shaft require a mezuza.” This is true for all elevator openings “on every floor,” just like the openings in the coop. He continues that “the elevator itself does not require a mezuza,” because the doors “are used only as a passageway and are used by people only when not in movement.”
Rav Shmuel Wosner zt”l agrees with Rav Blau, with one distinct difference. Since the elevator moves from floor to floor, it is always considered secondary to the building, and we therefore regard the opening of the elevator as an entrance to a room or lobby and not as an entrance to an elevator. Accordingly, the mezuza “must always be placed on the right of the exit from the elevator and not on the right of the entrance to it.”
To summarize this opinion, one must distinguish between the permanent doors located in the building’s walls, which require a mezuza on the right side of the entrance to the room, and the doors of the elevator itself, which are exempt from mezuza, as the elevator itself is defined as a temporary and mobile room.
Rav Asher Weiss shlita has a novel approach to this issue. He states that “an elevator is like a car.” Even though at first glance this approach seems somewhat unusual, Rav Weiss explains: “What is the difference between a car, which brings a person closer to his home from east to west, and an elevator that brings him closer to his home from below to on top?” Based on this comparison, he states as follows: “We have never heard someone say that entrances to trains, buses or cars require a mezuza… because these are not a place of living, but only a vehicle to bring a person to his home… and the same applies to an elevator, which has no characteristics of a dwelling place at all.”
Thus, contrary to all the opinions mentioned above that regard an elevator as some kind of dwelling space, Rav Weiss does not consider an elevator to have any element of dwelling at all, but rather regards it as a means of transportation that raises and lowers a person.
Rav Asher Weiss concludes that the permanent opening in the building is also exempt from mezuza because the elevator itself is exempt from a mezuza: “We do not find that all the rooms and places that are exempt from mezuza… must place a mezuza on the right of the entrance from these rooms into the house,” and as the opening to the elevator is defined as the opening to the elevator and not to the floor, it is exempt from mezuza. In other words, according to Rav Weiss, the opening in the building’s wall is defined as the opening of the elevator and not of the floor; therefore, if the elevator is exempt from mezuza, this is relevant to both openings of the elevator – the opening of the elevator itself and the permanent opening in the building.
We have examined two basic halachot of mezuza in this article, the halacha of a beit sha’ar and the halacha of a stairwell, and reviewed four different approaches of the poskim regarding elevators. One approach is to view the elevator as a beit sha’ar using one of two different understandings regarding the novelty of a beit sha’ar. Another approach is to consider elevators as a stairwell, and the fourth approach was that of Rav Asher Weiss of treating elevators as cars.
Many other Rabbis have written and discussed the obligation of a mezuza in an elevator, such as Rav Shlomo Zalman Auerbach, Rav Moshe Feinstein, and others, but we have limited the discussion to the four poskim mentioned above. I would like to conclude by mentioning the ruling of mori v’rabi, Rav Yaakov Ariel shlit”a, who claims that an elevator itself is a “room that is not used for living purposes, but only for passing through” and a mezuza is not required to be placed in the elevator itself. Regarding the exit from the elevator, he notes that “most of the world does not have the practice” to place a mezuza there because this “is not the regular entrance,” but only an entrance for those who have entered the floor through the elevator.
 Sukka 23b
 Halachot Ketanot L’Rosh (Masechet Menachot), Hilchot Mezuza, page 16.
 Halachot Ktanot L’Rif (Masechet Menachot), Hilchot Mezuza, page 6b.
 Hilchot Mezuza 6:2
 It should be noted that the basis for the Rosh’s chiddush is somewhat tenuous. He claims that all versions of the text of the baraita state “four amot,” and the Rif changed the phrase. However, in all versions known today, there is not even one like that described by the Rosh; rather, all state “four amot by four amot,” so it is difficult to “overload” the Rif with the Rosh’s opinion. This disadvantage does not detract from the Rosh’s opinion on its own terms, but only the ability to claim that the Rif agrees with it.
I believe we can add additional proof to the claim that the Rif does not agree with the Rosh because we generally prefer to explain the positions of the Rif and the Rambam as correlating with each other. Indeed, when the Beit Yosef explains this dispute of the Rishonim, he writes (Yoreh De’ah 286:13, s.v. umah shekatav) that “לענין הלכה נקיטינן כהרמב”ם דהא לא פליג עליה אלא הרא”ש.” In other words, the Beit Yosef does not accept the approach that the Rif agrees with the Rosh, because if so, he would have accepted the claim that he should rule in accordance with their opinion as he usually rules according to the majority of the three amudei hora’a, pillars of halachic decision: Rif, Rambam, and Rosh.
 Yoreh De’ah 286:13
 It should be noted that the Shach (Yoreh De’ah 286:23) comments on the Shulchan Aruch that Rabbeinu Yerucham says to rule like the Rosh, and he writes that this is how most poskim understand the halacha. But because of uncertainty, the Shach rules that in fact one should not say a beracha when placing a mezuza in such a room, as the Rambam requires a mezuza and the Rosh exempts the room.
 According to the Rosh, Chazal intended that each wall in the room must be at least four amot, regardless of the size of the room, so such a laundry room is exempt from a mezuza, as none of its walls are four amot
 Yoreh De’ah 286:11
 Rav Yitzchak Yaakov Weiss zt”l (5662–5749) was the head of the Eda Charedit, but his halachic influence expanded beyond the boundaries of this community. Indeed, much of his Minchat Yitzchak series of responsa was written in his home in London prior to moving to Israel.
 Minchat Yitzchak 4:93.
 Menachot 33b
 Rabbi Natan Gestetner zt”l (5692 – 5771) was a dayan, posek, and head of the Panim Me’irot Yeshiva in Bnei Brak. He was the author of dozens of sefarim.
 Lehorot Natan 3:73:1
 Lehorot Natan 3:73:11
 Regarding the lower floor, Rav Gestetner rules that the mezuza is placed on the right side of those entering the floor from the elevator (like the other floors), but one never recites a beracha even if there are four amot by four amot, because one could regard the elevator as a room that requires a mezuza, “and one who is leaving the elevator to the room” is considered as if he is going between the different rooms in his home, from the innermost to the outermost.
 Masechet Menachot 34a
 s.v. lul
 It should be noted that Rabbeinu Gershom explains the case a bit differently such that the dividers were not surrounding the stairs on the lower floor. Nevertheless, the discussion in the poskim is based on the explanation of Rashi and we have therefore focused only on his opinion.
 Yoreh De’ah 286:19
 Chovat HaDar, Chapter 5
 Rav Yitzchak Weiss referred to this claim and writes that it has already been ruled (Da’at Kedoshim 276:1) that a mobile tent requires a mezuza when it is standing on the ground, and even when being moved around it requires a mezuza if it can withstand the wind. He thus refutes Rav Blau’s opinion. Rav Blau discusses this claim and responds that an elevator is less mobile than a temporary tent, as it is part of a building and has become part of its regular use. Therefore, an elevator must be compared to an apartment building, and not to a tent.
 Kovetz Mibeit Levi 2:9:11.
 Rav Asher Zelig Weiss is a prominent posek in Ramot, Jerusalem, founder and head of the Darkei Torah Beit Midrash and Av Beit Din of Darkei Hora’a. He also serves as the posek of the Shaare Zedek Medical Center in Jerusalem, and is the head the court of monetary affairs. He has published dozens of books, all under the title Minchat Asher, including many responsa and analytical works on various tractates of Shas. He is considered one of the greatest rabbis of our generation.
 Responsa Minchat Asher Vol.1, Yoreh De’ah 56
 Shut Minchat Shlomo, Tanyana 2:100:5
 Brought in Orchot Rabbeinu, Section 4, p.244, 28.
 In a responsum available on the website of Machon HaTorah V’ha’aretz at: https://tinyurl.com/yyha7pra.