Question: We are adding a floor to our house. At first, we will access it from the house, but we may eventually make it a separate unit with access via stairs from the street. Therefore, we made a door on the side of the street – during construction it is accessed by a temporary ramp, but then it will be sealed until if and when we build stairs. Does that door require a mezuza now? If we put one up, will it be able to stay if we open it, or will it be ta’aseh v’lo min he’asuy (=tvlmh; pasul because it came into a proper mitzva state without a direct action)?
Answer: To be obligated in mezuza, a doorway and the adjacent area must have certain structural characteristics (Shulchan Aruch, Yoreh Deah 286:6-17), one needs to own it on some level (Menachot 44a; see Tosafot ad loc.), and the area must serve a recognized function (Shulchan Aruch, ibid. 1-2). During construction, the function is normally missing. Even after one buys or builds a house that is ready for use but people have not moved in, there is no obligation for a mezuza (Magen Avraham 19:1; Birkei Yosef 19:2). Even after starting to use, one’s obligation stops if he abandons the place or rents it out (Tosafot ibid.). So you do not yet need a mezuza for either entrance.
When the extension is ready, if the external door was not made to be used at all past the construction stage, the obligation will not begin on it (see Shulchan Aruch, YD 186:17-18). If it will be used for a while and the ramp will be removed later, then it will require a mezuza. Then, if the door will be sealed shut for a long time, that likely uproots the obligation (see Pitchei She’arim 286:208; Shut Shevet Sofer, YD 92). If the mezuza remained, there would be a machloket upon putting in the stairs whether it would be tvlmh, and it should be removed and returned (Pitchei Teshuva, YD 286:13); what to do about a beracha is beyond our present scope.
Is it good/okay to be "machmir" and put up the mezuzot while construction is in process? Mezuza resembles tzitzit (Tosafot and Birkei Yosef ibid.); they are activated by wearing a garment/living in a house. The mitzva act is attaching the tzitzit/mezuza to the garment/doorpost. We tie on the tzitzit well before the mitzva is fulfilled upon wearing it. (There is a machloket whether one may put the garment on and then start tying on the tzitzit - see Tosafot, Yevamot 90b and Rambam, Tzitzit 3:10.) We might then expect that if one put up the mezuza before moving in, he would make the beracha when moving in. The Magen Avraham (ibid.) believes there is a beracha with different language if one moves into a house that already has mezuzot. Rabbi Akiva Eiger (Shut I:9) thought that logic dictated that anytime a person leaves his house for several days, he would make a new beracha upon returning. We accept the Birkei Yosef (ibid.), who argues that the beracha on mezuza was instituted for the last time one is involved in the mitzva, which is when one attaches it to the wall. But then that should be at a time of obligation.
According to most poskim, the best time to attach the mezuza is around the time that one begins to live in the house, either right before (Da’at Kedoshim 289:2) or after one starts living there (see Chovat Hadar 3:(7)). If it is too early, it will not be possible to make a beracha as there is no obligation yet. Some say that once one starts moving his possessions into the house, it is close enough (see Dirshu 19:3).
The classic case of tvlmh is when one attaches a mezuza before the elements for mezuza exist (including when the door led to nowhere or when the area is a construction site). If one attached it when the area was ready to be used but he just did not start using it, according to most opinions it is a valid attaching, and he would not have to redo it when the time came (see Sdei Chemed, vol. V, p. 59; Keren Ora, Menachot 44a). However, he could not make a beracha when attaching it (making the beracha later is complicated – see Chovat Hadar 11:(22)); thus, doing it clearly early is likely not positive.
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