Parshas Vayekheil: Women Building The Beis HaMikdash

The Rambam paskens in Hil Beis HaBechira 1:11 that women are obligated to help build the Beis HaMIkdash. The Kesef Mishna writes that the m'kor is from Parshas VaYekheil which states that women contributed to the Mishkan. However, the Rambam also paskens that you can't build the Beis HaMikdash at night nor on Shabbos and Yom Tov. If so that would mean building teh Beis HaMikdash is a mitzvas aseh sh'hazman grama and women should be patur. Why then are they chayav.

There are a number of approaches to this question

Sefer HaChinuch

The Sefer HaChinuch writes that building the Beis HaMikdash is a mitzvah on teh whole tzibbur and not on individual. Also, the Rambam at the end of Sefer HaMitzvos counts this mitzvah as one of those mitzvos applying to the whole tzibbur. If so one can argue that it is irrelevent whether this mitzvah is a mitzvas aseh sh'hazman grama, since it applies to the tzibbur.

Beis Yitzchak/Turei Even

The Beis Yitzchak (Orach Chaim Siman 3) answers the question based on a Turie Even. The Turei Even in Chagiga 15b says that the issue of mitzvas aseh sh'hazman grama only applies when teh zman is mevateil the mitzvah. However, when it is only mafsik/interrupts the mitzvah then mitzvas aseh sh'hazman grama doesn't apply. For example, there is a question whether women are chayav to do semicha on a korbon. The Turei Even asks why don't we say it is a mitzvas aseh sh'hazman grama since you can't do it at night. He answers that the mitzvah of semicha on a particular korbon only applies once in a person's lifetime. Once you do the semicha on an animal you never need to do it again. Therefore, if you don't do semicha on Monday and Monday night comes, the semicha of Tuesday is not a new mitzva-it is the same mitzvah which you didn't do yesterday. The only reason you couldn't do it Monday night was because the nigt interrupted your performance of the mitzvah. However, by tefillin, the mitzvah of Monday is notthe same mitzvah as Tuesday. It is a totally new mitzvah. When Monday night comes, the night is mevateil your Monday mitzvah-you can never do it again.

The Beis Yitzchak says that building the Mikdash is like semichas hakorbon. It only applies once-after it is built the mitzvah is over. Night is just an interruption not a bittul.

Kehillas Ya'akov

The Steipler has a similar mehalach in regards to why the petur of Shabbos doesn't make it a mitzvas aseh sh'hazman grama. He quotes a Sha'ar HaMelech at the end of pesulei hamukdashin (in discussing nosar) that if the mitzvah applies on Shabbos just that you can't do it because of issurei Shabbos then it is not a mitzvas aseh sh'hazman grama. In theory the mitzvah to build the Beis HaMikdahs exists on Shabbos it is only because of issurei Shabbos that we can't. This is not like tefillin where there are no issurei Shabbos preventing you from putting tefillin on. Rather, the Torah says the mitzvah itself doesn't apply on Shabbos.

Klei Chemdah (Ki Sisa)

The Klei Chemdah answers that it is only a mitzvah to have the Mikdash built and not too build it. Therefore, it can apply to women. (He actually rejects this answer but I mentioned it anyway)