Many homes do not have a Mezuzah in every place that requires one. For example, utility rooms and garages require a Mezuzah (see Shulchan Aruch Yoreh Deah 286:2). Many families also do not have Mezuzot affixed to their walk-in closets or entrances to porches. In this essay, we shall discuss whether this practice is correct or not.
The Four Amah Requirement - Rambam vs. Rosh
The Gemara (Sukkah 3a) teaches that we are not required to attach a Mezuzah to a house which is smaller than four Amot (cubits) by four Amot. The Rishonim debate whether the Gemara requires a minimum length and width of four Amot (Rosh Hilchot Mezuza number 16) or just an area of sixteen square Amot regardless of length and width (Rambam Hilchot Mezuzah 6:2). For example, if an area is eight Amot long and two Amot wide, it is sixteen Amot square, but is not four Amot wide. In such a case, a Mezuzah is required according to the Rambam but not according to the Rosh. This issue is quite relevant, as many walk-in closets have narrow corridors but are quite long.
The Shulchan Aruch (Y.D. 286:13) rules in accordance with the view of the Rambam and does not even cite the dissenting view of the Rosh. In the Beit Yosef (Y.D. 286 s.v. UMah SheKatav Oh SheEin Bo), he explains that the Rambam's view is authoritative because no one agrees with the Rosh on this matter. The Shach (ad. loc. number 23), however, notes that Rabbeinu Yerucham agrees with the Rosh.
The Shach therefore concludes that one should affix a Mezuzah in such a situation in accordance with the Rambam, but should omit the Berachah in deference to the Rosh. Alternatively, if one attaches Mezuzot to an area of such dimensions on the same occasion as he affixes a Mezuzah to an area that certainly requires a Mezuzah, one should recite the Berachah before affixing the Mezuzah to the latter area and bear in mind that the Berachah should also apply to the attaching of the Mezuzah to the former area. The Aruch HaShulchan (Y.D. 286:21) rules in accordance with the opinion of the Shach.
The question, though, is how to define an Amah. This matter is hotly debated among twentieth century Poskim. Rav Avraham Chaim Naeh rules that it is 18.9 inches, while the Chazon Ish believes that it is 22.8 inches. Rav Hershel Schachter and Rav Mordechai Willig told me that we should follow the ruling of Rav Moshe Feinstein (Teshuvot Igrot Moshe Orach Chaim 1:136), who believes that an Amah is 21.25 inches. Indeed, the Aruch HaShulchan (Y.D. 201) presents as almost identical Shiur for an Amah. On the other hand, Rav Feivel Cohen (Badei HaShulchan, addendum to Hilchot Niddah, printed in the Badei HaShulchan to Hilchot Basar BeChalav p. 385) writes that he believes that the common practice is to be strict and accommodate both the smaller and larger versions of an Amah. Regarding our issue, Rav Avraham Chaim Naeh's opinion is the strict one and should be followed if one adopts Rav Cohen's approach. One should consult his Rav regarding
which opinion should be followed.
We should note that walk-in closets which are four Amot long and four Amot wide are no different than any other room, and require a Mezuzah according to all opinions.
Teshuvot Chamudei Daniel
Many, perhaps most, walk-in closets do not even encompass an area that is sixteen Amot square and would seem not to require a Mezuzah. However, Teshuvot Chamudei Daniel (cited in Pitchei Teshuva Y.D. 286:11) severely limits the Gemara's exemption of an area of less than four by four Amot. He rules that this exemption applies only to an entire residence that is less than four by four Amot. However, if an area of a house (such as a storage area) is normally less than four by four Amot, it would require a Mezuzah. Indeed, the Rosh (ad. loc.) explains that a house that is less than four by four Amot is not suitable for residence and therefore does not require a Mezuzah. However, many storage areas are smaller than four by four Amot, and the reasoning to exempt a small area from Mezuzah does not seem to apply to them.
The Pitchei Teshuva does not cite any opinion that disagrees with the Chamudei Daniel, and Teshuvot Minchat Yitzchak (4:92) notes that many Acharonim agree with this view. On the other hand, Rav Ovadia Yosef (Teshuvot Yechave Daat 4:51) notes that many Poskim disagree with the Chamudei Daniel.
We should note that the Chamudei Daniel's ruling applies only to an area which one enters. Thus, if the Teshuvot Chamudei Daniel is accepted, a Mezuzah is required to be affixed on the right side (as one enters) of a walk-in closet. However, Dayan Weisz (Teshuvot Minchat Yitzchak 3:103) writes all would agree that an area that one does not enter, such as a pantry or closet that is not a walk-in, does not require a Mezuzah.
Rav Akiva Eiger
Rav Akiva Eiger (commentary to Shulchan Aruch Y.D. 286:13) places a further limitation on the four by four Amot exemption. He believes that it does not apply if the area that is less than sixteen square Amot leads into an area that requires a Mezuzah. He rules that one is required to affix a Mezuzah to the right side as one leaves the small area into the larger area. Even though the small area is in and of itself exempted from a Mezuzah, one is required to affix a Mezuzah just as one places a Mezuzah on the doorway to his home. In that case, one places a Mezuzah on the right side entering the house, since one enters from an area that does not require a Mezuzah (the outside) to an area that requires a Mezuzah (one's home). According to Rav Akiva Eiger, one would place a Mezuzah on the right side as one leaves a walk-in closet if it enters a room which requires a Mezuzah (as it does in virtually all situations), as one is leaving an area
that does not require a Mezuzah (the walk-in closet) to an area that requires a Mezuzah (such as a bedroom).
We should emphasize, however, that according to the Chamudei Daniel's approach (which Rav Akiva Eiger implicitly rejects), one is required to affix a Mezuzah on the right side as one enters a walk-in closet. Since it is not a viable Halachic option to affix Mezuzot on both doorposts (this might violate Bal Tosif, see Pitchei Teshuva Y.D. 291:2 and Teshuvot Igrot Moshe Y.D. 1:176 in the postscript to the responsum), Poskim must decide whether to follow Rav Akiva Eiger or the Chamudei Daniel, as it is impossible to accommodate both views.
Although the Aruch HaShulchan (Y.D. 286:23) rules in accordance with Rav Akiva Eiger, some Acharonim dispute or limit his view. The Gedolei Hekdesh (289:9, cited by Teshuvot Minchat Yitzchak ad. loc.) argues that the entrance to an area less than four Amot by four Amot does not constitute an entrance, and therefore does not require a Mezuzah. Dayan Weisz asserts that even Rav Akiva Eiger's ruling applies only in a case in which the entrance to the small area serves another function in addition to serving as the entrance to that small area. Rav Moshe Feinstein (Teshuvot Igrot Moshe Y.D. 1:181) writes that Rav Akiva Eiger's assertion is "bewildering" and that "in practice one is not required to accommodate his view." Rav Ovadia Yosef (ad. loc.) does not even consider the opinion of Rav Akiva Eiger in his ruling (he cites Rav Moshe as one of his many precedents for this approach).
A similar issue applies to affixing a Mezuzah to a porch (or a deck). A porch would seem not to require a Mezuzah, since it does not have a roof (Shulchan Aruch Y.D. 286:14). However, one could claim that it does require a Mezuzah either because it is normal for a porch not to have a roof (similar to the approach of the Chamudei Daniel) or that one should affix the Mezuzah on the right side as one enters the house from the porch based on Rav Akiva Eiger. The Aruch HaShulchan (ad. loc.) explicitly applies Rav Akiva Eiger's ruling to an area that does not have a roof.
A consensus view has not emerged among contemporary Poskim regarding this issue. The Chazon Ish (Y.D. 168:5) rules that one should affix a Mezuzah on the right side as one enters a house from a porch, while Rav Ovadia Yosef (ad. loc.) cites many Poskim, such as Rav Yaakov Emden and Rav Shlomo Kluger, who rule that it should be placed on the right side as one leaves one's home to enter the porch. Rav Yosef concludes that essentially a porch does not require a Mezuzah, but one who affixes a Mezuzah at the entrance to his porch "will have a Berachah bestowed upon him." Rav Yosef rules that those who affix a Mezuzah to their porch entrance should do so on the right side as one leaves the house to enter the porch.
During the years when I studied at the Kollel at Yeshiva University, there was a Mezuzah affixed to the right side as one left the walk-in coat closet in the third floor Beit Midrash in Furst Hall, in accordance with the view of Rav Akiva Eiger. I was informed that this practice stemmed from a ruling issued by the founding Rosh Kollel, Rav Aharon Lichtenstein, and subsequently endorsed by his successor, Rav Hershel Schachter.
Many individuals do not have Mezuzot attached to their walk-in closets, and they certainly have many opinions upon which to rely. One who adopts the strict view and attaches a Mezuzah to a walk-in closet (either to the right or left side) should most likely omit the Berachah in deference to the many opinions who rule that walk-in closets do not require a Mezuzah.
In practice, one should inquire of his Rav as to whether walk-in closets and porches require a Mezuzah and to which side it should be affixed. Moreover, it is highly recommended for one to invite his Rav to visit his home for an inspection to insure that Mezuzot are affixed in all of the required areas and that they are attached to the proper side of the doorway.